WO2025242515A1 - Système photonique et procédé de conversion de fréquence de pompes laser - Google Patents

Système photonique et procédé de conversion de fréquence de pompes laser

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Publication number
WO2025242515A1
WO2025242515A1 PCT/EP2025/063293 EP2025063293W WO2025242515A1 WO 2025242515 A1 WO2025242515 A1 WO 2025242515A1 EP 2025063293 W EP2025063293 W EP 2025063293W WO 2025242515 A1 WO2025242515 A1 WO 2025242515A1
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WO
WIPO (PCT)
Prior art keywords
waveguide
laser pump
laser
phase
frequency
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/063293
Other languages
English (en)
Inventor
Mikkel Torrild HANSEN
Emil Zanchetta ULSIG
Nicolas Volet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Aarhus Universitet
Original Assignee
Aarhus Universitet
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Filing date
Publication date
Application filed by Aarhus Universitet filed Critical Aarhus Universitet
Publication of WO2025242515A1 publication Critical patent/WO2025242515A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
    • G02F1/3534—Three-wave interaction, e.g. sum-difference frequency generation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0121—Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
    • G02F1/0123—Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/365—Non-linear optics in an optical waveguide structure
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/37—Non-linear optics for second-harmonic generation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/35—Non-linear optics
    • G02F1/37—Non-linear optics for second-harmonic generation
    • G02F1/377—Non-linear optics for second-harmonic generation in an optical waveguide structure

Definitions

  • the present invention relates to a photonic system and method for frequency conversion of incoming laser pumps which utilizes phase modulation to generate and modulate infrared light. BACKGROUND OF THE INVENTION
  • lasers are commonly used as a source of light beams or pumps due to their high intensity and coherence.
  • Waveguides and optical combiners, such as multiplexers, are often employed to direct and manipulate laser beams.
  • Frequency conversion techniques such as difference frequency generation (DFG), sum frequency generation (SFG), second harmonic generation (SHG) or spontaneous parametric down conversion (SPDC) are used to convert the frequency of the laser beams to a desired frequency.
  • DFG is a nonlinear optical process where two input beams or pumps with different frequencies interact within a nonlinear material to generate a signal at the difference of the two frequencies.
  • SFG is a process where two input pumps combine in a nonlinear optical medium to form an output signal at the sum of the input frequencies.
  • SHG is a special case of SFG in which the two input pumps with the same frequency, therefore combining to generate an output signal at the double frequency of either of input pumps.
  • SPDC is a special case of DFG in which the two input pumps with the same frequency, or a single input pump, spontaneously generate two outputs with their sum of frequencies equal to the input pump(s).
  • the field of photonics has seen significant advancements, particularly in the area of laser light manipulation on photonic chips, where optical on-chip components guide and manipulate light.
  • current frequency conversion systems typically rely on free space optical setups and bulk nonlinear crystals. Such systems face several challenges.
  • the free space optical setups in which the pump laser beams are coupled into bulk nonlinear crystal require significant space 83690PC01 2 on the order of 50cm x 50 cm x and often more. This limits their applicability in settings where space is at a premium.
  • phase-shifting means to obtain a phase change of one or more pump(s) or signal(s) to optimize optical interactions between the pump(s) and signal(s) in a waveguide.
  • 83690PC01 3 It is a further object of the present invention to provide an alternative to the prior art.
  • a photonic system for frequency conversion of incoming laser pump(s) the photonic system is comprising: - a first laser source, which is arranged to generate a first laser pump at a first frequency f1, - a second laser source, which is arranged to generate a second laser pump at a second frequency f2, - a first waveguide, which is nonlinear comprising a second-order nonlinear optical susceptibility material for frequency conversion, - an optical combiner, which is arranged to combine the laser pumps from the first laser source and the second laser source, and direct the combined pumps into the first waveguide, and - an input coupler to couple the first laser pump and the second laser pump, wherein - the first waveguide and the optical combiner are integrated into a compact platform, - the first waveguide is arranged to frequency convert the first laser pump and the second laser pump to generate a frequency converted signal of a
  • the photonic system is an optical device that provides phased-locked generation, amplification and/or modulation of a frequency converted signal by carefully modulating the phase of the first laser pump, the phase of the second laser pump and/or the phase of the frequency converted signal.
  • the first laser source and the second laser source may be laser diodes, or any other kind of emitting laser pump at the required wavelength.
  • the optical combiners, waveguides, and phase shifting means to control the phase of the laser pumps and/or the frequency converted signal are integrated on a compact platform, which preferably may be a photonic chip.
  • the words pump and signal in this application both refer to beams of light comprising a certain center wavelength.
  • the distinction between pump and signal is that the pump are sources of light in-coupled at the input, while the signal is generated from the pump sources and is the desired entity at the output. Occasionally the word “beam” is used in this application instead of pump or signal or to cover both pump and signal, so a beam may be a pump or a signal.
  • the optical combiner is a device which combines the pumps from two or more laser sources and leads the pumps into the first waveguide.
  • the optical combiner may be a multiplexer.
  • the multiplexer is preferably made of the same material as the compact platform.
  • the input coupler is a laser-to-chip receiving the laser pumps and coupling the laser pumps into the photonic chip.
  • the first waveguides may be fabricated in III-V semiconductor materials with large second-order nonlinear optical susceptibility, preferably the nonlinear waveguide is fabricated in or based on GaP, InGaP, GaAs, AlGaAs, InP, InGaAsP, lithium niobate or another binary, tertiary or quaternary etc. III-V semiconductor material, with high second-order nonlinear optical susceptibility. Materials with a high refractive index and large nonlinear second-order susceptibility are used, while the materials are transparent at the relevant wavelengths.
  • the first waveguide is nonlinear comprising a nonvanishing second-order nonlinear optical susceptibility material for frequency conversion.
  • the compact platform may be a photonic chip with embedded photonic integrated circuit(s) (PIC(s)) which allows for a compact, robust, and miniature system, and has been shown to improve the nonlinear conversion due to tighter guiding of the modes, allowing for a higher conversion efficiency.
  • PIC(s) embedded photonic integrated circuit
  • the first waveguide and the optical combiner are integrated into a compact platform
  • the compact platform may be entirely a photonic chip with embedded PIC(s) in which the optical combiner, the couplers, and the nonlinear waveguides are structurally integrated.
  • Structural integration is to be understood as the structural integrated components are grown and fabricated as part of the compact platform, the component being made of the same material as the compact platform, or the structural integrated components are bonded to the compact platform.
  • the compact platform may be a photonic chip made of silicon, silicon nitride and/or silica, and the nonlinear material.
  • the phase shifting means may be integrated into the compact platform or may alternatively be attached to the compact platform. Phase shifting means are related to the complex exponential with a phase argument, not to be misinterpreted as the phase matching condition, which happens on the basis of the wavenumbers. 83690PC01 6
  • the substrate of the compact platform and its nonlinear material is typically either grown on top of each other or the nonlinear material is bonded onto the substrate of the compact platform. It may then be further processed to fabricate the waveguide in the nonlinear material by etching. The etching can form the waveguide by removing materials both on top, but also beneath (under-etching).
  • An optical phase modulator is a device that varies the phase of a light beam in response to an electrical signal.
  • the electrical signal may be generated by a phase shift controller.
  • the characteristics of the electrical signal dictate the phase of the light beam. This characteristics of the electrical signal may be amplitude of the signal or frequency. As the characteristics of the electrical signal change, the phase of the light beam changes correspondingly generating the phase-shifted signal.
  • Modulation refers to any controlled change of the first or second laser pump or the frequency converted signal by changing the phase of the beam.
  • the modulated frequency converted signal is obtained by the frequency converted signal having been phase shifted then to subsequently further stimulate the frequency conversion process by optically interacting with the first or second laser pumps in the first waveguide.
  • the modulated frequency converted signal may also be obtained by the frequency converted signal having optically interacted with the phase shifted first or second laser pumps in the first waveguide.
  • the modulated frequency converted signal becomes the output signal when the modulated frequency converted signal leaves the waveguide through the output port. 83690PC01 7 Passing through the first the frequency converted signal is gradually changed to the modulated frequency converted signal during optical interaction with the different beams moving within the first waveguide.
  • Optical interaction refers to the process by which two or more laser pumps and/or frequency converted signals interact within the first waveguide. This optical interaction can result in frequency conversion processes leading to amplitude enhancement or attenuation of one or more of the interacting pumps and signals. The specific outcomes of the optical interaction depend on the properties of the first waveguide, the characteristics of the laser pumps, and the nature of the nonlinear interaction.
  • the invention requires finding the right material and dimensions for the nonlinear waveguide and selecting the right laser sources and multiplexer and to find the right temperature to achieve the laser pumps to optical interact in the nonlinear waveguide to facilitate the desired frequency conversion.
  • the output signal is a modulated frequency converted signal with its frequency generated by frequency conversion of the laser pump from the first laser source and the laser pump from the second laser source and optical interaction between the pumps and frequency converted signal.
  • the first laser pump from the first laser source and/or the second laser pump from the second laser source may be phase shifted before the frequency conversion.
  • the frequency converted signal may be phase shifted after the frequency conversion, which hence will be recombined in the first waveguide to modulate the output signal based on the phase-shift.
  • the invention is particularly, but not exclusively, advantageous for obtaining a photonic system and method comprising phase-shifting means to obtain phase- shifting of one or more beam(s) to optimize optical interactions between the beam(s) in the first waveguide obtaining a frequency converted output signal of a high amplitude by adjusting the phase of one or more of the first laser pump, the second laser pump and/or the frequency converted signal to optimize the optical interaction in the first wave guide.
  • the phase shifting means are a first phase modulator, a second optical phase modulator and/or a second waveguide.
  • the optical phase modulator is able to phase shift by actively phase modulating the first laser pump, the second laser pump and/or the frequency converted signal.
  • the phase shifting means are a first phase modulator.
  • the first phase modulator is positioned to phase shift the first laser pump and/or the second laser pump before the first and second laser pump enters the optical combiner.
  • the phase shifting means are a second optical phase modulator and/or a second waveguide.
  • the second waveguide and possibly the second optical phase modulator are positioned so that the first laser pump, the second laser pump and/or a frequency converted signal may enter the second waveguide by evanescent coupling after the first laser pump and the second laser pump have entered the first waveguide.
  • the incoming beams are phase shifted either by the second waveguide itself or by a second optical phase modulator placed in or at the second waveguide.
  • the phase shifted signal is then returned by the evanescent coupler to the first waveguide. 83690PC01 9
  • the incoming beams are phase by the second waveguide itself, it is the length and refractive index of the second waveguide that causes the phase shift, as the length may cause the incoming beams may be returned to the first waveguide offset and thereby phase shifted relative to the first laser, pump, the second laser pump or the frequency converted signal.
  • the optical phase modulator is able to phase shift by actively phase modulating the first laser pump, the second laser pump and/or the frequency converted signal.
  • Phase modulation may be performed by various methods, all of which introduce a phase shift of a given light beam by controlling a physical mechanism.
  • One physical mechanism is the electrical-optical effect, where an applied voltage across the second waveguide changes the refractive index, which resultingly will introduce a phase shift related to the magnitude of the applied voltage.
  • a second physical mechanism is a thermal-optical effect in which the temperature of the waveguide is adjusted locally, which resultingly will alter the refractive index locally and hence introduce a phase shift.
  • a third physical mechanism is controlling the optical path length that the optical beam covers by straining the waveguide by applying stress on the waveguide.
  • a fourth physical mechanism is controlling the amplitude of the lasers, or including a cavity with a high intense field that will trigger third-order nonlinear effects also known as the Kerr effect and cross-phase modulation which changes the effective refractive index and can induce a phase-shift.
  • These physical mechanisms may be applied to the first laser pump, the second laser pump and/or the frequency converted signal.
  • the second waveguide may be fabricated in the same material as the first waveguide, but may alternatively be fabricated in other materials, which may not be nonlinear. Therefore, the second waveguide may be a nonlinear waveguide, or it may not be a nonlinear waveguide.
  • the second waveguide may be a resonator or may be coupled to a resonator for having intense fields for Kerr effects, using the Kerr effect to induce phase-shift.
  • means are arranged to phase shift the first laser pump, the second laser pump and/or the frequency converted signal within the second waveguide to generate phase-shifted signal(s).
  • - an evanescent coupler is arranged to couple one, or more, of the beams from the first waveguide into the second waveguide as incoming beam(s), where the incoming beam(s) from the first waveguide is/are: a . the first laser pump, b. the second laser pump, and/or c.
  • a frequency converted signal which is generated by frequency conversion of the first laser pump and the second laser pump, and - the evanescent coupler is further arranged to couple the phase- shifted signal(s) from the second waveguide into the first waveguide.
  • the second waveguide may be arranged to phase shift the incoming beam(s) by the evanescent coupler which may be a directional optical coupler which transfers beams between the waveguides.
  • the evanescent coupler transfers beams from the first linear waveguide to the second linear waveguide, or from the second linear waveguide to the first linear waveguide.
  • the evanescent coupler may be implemented by the first and second waveguides and are sufficiently closely spaced that beams are optically transferred between them by evanescent coupling.
  • the light beams may be the first laser pump, the second laser pump or the frequency converted signals.
  • One, or more, of these light beams are partially transferred to the second waveguide through the evanescent coupler.
  • the light beam transferred to the second waveguide is the incoming beam. 83690PC01 11
  • the specific light beams(s) from the part that is transferred is determined by the dimensions, the material of the second waveguide and gap between the first and second waveguide.
  • the evanescent coupler facilitates the selective interaction between the beams in the first waveguide and the second waveguide, enabling the transfer of a fraction of the desired light beam.
  • the first waveguide is further arranged so that the phase-shifted signal(s) optically interacts with the first laser pump, the second laser pump and/or the frequency converted signal to generate a modulated frequency converted signal with the same frequency as the frequency converted signal.
  • the phase shifting means arranged to phase shift the first laser pump (6), the second laser pump (7) and/or the frequency converted signal (10) within the second waveguide (11) comprises a second optical phase modulator (12’’).
  • the first optical phase modulator is arranged to phase shift the first laser pump and/or the second laser pump subsequent to being in-coupled and before entering the optical combiner.
  • an optical phase modulator is placed before the optical combiner in the input coupler, but the optical phase modulator is placed on the compact platform, so the pump is in-coupled to the compact platform before it is phase shifted. It is possible to have phase modulators both before the combiner and in the second waveguide.
  • Phase modulation is performed by adjusting the electrical signal transmitted from the phase shift controller to the optical phase modulator which may be adjusted either manually or by a computer interface.
  • arranging the second waveguide to phase shift the incoming beam(s) comprises adapting the refractive index of the second waveguide.
  • the refractive index of the second waveguide may be adapted by the electrical- optical-effect and/or thermal-optical effect, adapting the length of the waveguide by a stress-strain effect or by the Kerr effect.
  • the compact platform comprises a photonic chip with embedded integrated circuit(s) (PIC(s)).
  • the frequency conversion is performed by difference frequency generation (DFG), or by sum of frequency generation (SFG), or by second harmonic generation (SHG), or by spontaneous parametric down conversion (SPDC).
  • DFG difference frequency generation
  • FSG sum of frequency generation
  • SHG second harmonic generation
  • SPDC spontaneous parametric down conversion
  • the first waveguide comprises an input end, where the laser pumps enter the first waveguide, and a first reflector is arranged at the input end of the first waveguide.
  • the first reflector may be specifically targeted to only reflect the signal wavelength.
  • the first reflector is arranged to reflect the phase- shifted signal(s) received from the second waveguide.
  • the phase shifted signal When the phase shifted signal enters the first waveguide from the second waveguide the phase shifted signal may be moving the opposite direction than the laser pumps, moving towards the input end, therefore, a first reflector may be positioned at the input end to reflect the phase shifted signal, so it moves in the same direction as the laser pumps.
  • the second waveguide comprises a remote end oppositely placed from an input end, where the input end is the end where the incoming beam enters the second waveguide, a second reflector is mounted at the remote end of the second waveguide, and the second reflector is arranged to reflect beams progressing within the second waveguide back through the second waveguide to be coupled back into the first waveguide.
  • the incoming beam When the incoming beam enters the second waveguide, it may travel from the input end towards the remote end.
  • a reflector is positioned to return the incoming beam back through the second waveguide such that the phase-shifted signal is returned to the first waveguide.
  • the optical combiner is a multiplexer, being arranged to combine the first laser pump from the first laser source with the second laser pump from the second laser source.
  • the evanescent coupler is a directional coupler. 83690PC01 14
  • the photonic chip comprising photonic integrated circuits (PICs) preferably is less than 20 mm2, more preferably less than 5 mm2, and even more preferably less than 3 mm2.
  • the wavelength ⁇ 1 of the first laser pump is between 380 nm and 2500 nm, preferably between 700 nm and 2000 nm.
  • the wavelength ⁇ 2 of the second laser pump is between 380 nm and 2500 nm, preferably between 700 nm and 2000 nm.
  • the second-order optical nonlinearity of the material used to manufacture the waveguides is larger than 1 pm/V, preferably larger than 50 pm/V, more preferably larger than 100 pm/V.
  • the optical loss in the waveguides is less than 15 dB/cm, preferably less than 10 dB/cm, more preferably less than 5 dB/cm.
  • the invention relates to a method for frequency conversion of incoming laser pumps using a photonic system according to the first aspect of the invention.
  • the invention relates to a computer implemented software which controls the photonic system according to the first aspect of the invention.
  • the computer implemented software may be implemented in programmable electronics.
  • the first, second and third aspects of the present invention may each be combined with any of the other aspects.
  • FIG. 1a and 1b illustrate an overview of the dynamics in an embodiment of the photonic system. 83690PC01 16
  • Fig. 2 illustrates an embodiment of photonic system with an optical phase modulator modulating the first laser pump.
  • Fig. 3 illustrates an embodiment of the photonic system with an optical phase modulator modulating the second laser pump.
  • Fig. 4 illustrates an embodiment of the photonic system with an optical phase modulator modulating the first laser pump according to a feedback signal.
  • Figs. 5a and 5b illustrate in a simplified overview the dynamics of an advanced embodiment of the photonic system of the embodiment with a second waveguide Fig.
  • FIG. 6 illustrates an embodiment of the photonic system with an optical phase modulator at the second waveguide modulating the frequency converted signal in the second waveguide.
  • Fig. 7 illustrates an embodiment of the photonic system with an optical phase modulator at the second waveguide modulating the first laser pump in the second waveguide.
  • Fig. 8 illustrates an embodiment of the photonic system with an optical phase modulator at the second waveguide modulating the second laser pump in the second waveguide.
  • Fig. 9 illustrates an embodiment of the photonic system with an optical phase modulator at the second waveguide modulating either of the pumps or signal in the second waveguide according to a feedback signal.
  • Fig. 10 shows a diagram illustrating a simulation of the power of the first laser pump, the second laser pump and the output signal at different phase shifts of the first laser pump.
  • Fig. 11 is a flow-chart of a method according to the invention.
  • DETAILED DESCRIPTION OF AN EMBODIMENT Figs. 1a and 1b illustrate an overview of the dynamics in an embodiment of the photonic system of the invention.
  • Fig. 1a shows a compact platform 1, which preferably is a photonic chip with embedded integrated circuit(s) (PIC(s)), the first laser source 2 is generating a first laser pump 6, the second laser source 3 is generating a second laser pump 7.
  • the first laser pump 6 enters an optical phase modulator 12’ on the photonic integrated circuit 1, the first laser pump 6 is phase shifted in the optical phase modulator 12’, and the phase shifted signal 22 and the 83690PC01 17 second laser pump 7 enters the first waveguide 9.
  • PIC photonic chip with embedded integrated circuit
  • phase shift controller 26 is arranged to control the optical phase modulator 12’ to regulate the phase shift that is applied to the optical beam by the optical phase modulator 12’.
  • An electric signal 32 is sent from the phase shift controller to the optical phase modulator 12’.
  • the characteristic of the electrical signal determines the magnitude of the phase shift applied the optical beam.
  • the phase shift controller 26 comprises an electrical contact pad 14 with an input port 15 (See Fig. 2).
  • Fig. 1b is illustrating the same photonic system of Fig. 1a with an additional feedback mechanism, where the output signal 33 is transmitted as a feedback signal 31 to the phase shift controller 26.
  • the phase shift controller 26 then may adjust the phase shift taking place in the phase shift controller by changing the electric signal 32.
  • Figs. 2-4 illustrate the embodiment of Fig. 1a and 1b in more detail.
  • Fig 2 shows a compact platform 1 which is a photonic chip with a photonic integrated circuit 1, the first laser source 2 generating a first laser pump 6 with frequency f1, the second laser source 3 generating a second laser pump 7 with frequency f2.
  • Input couplers 4, 5 are coupling the first laser pump 6 and the second laser pump 7 into the PIC 1.
  • the first laser pump 6 is phase shifted by the optical phase modulator 12’ obtaining a phase-shifted signal 22 which enters the optical combiner 8, together with the second laser pump 7.
  • the optical combiner 8 may be a multiplexer.
  • the phase shift controller 26 controls the phase shift.
  • the phase shift controller 26 comprises an electrical contact pad 14 with an input port 15 for an electrical signal.
  • An electrical wire 13 connects the contact pad 14 to the optical phase modulator 12’ for transmitting the electrical signal 32 controlling the phase shift by either changing the refractive index by an electrical-optical effect or a thermal optical effect, or by changing the optical path length by inducing a stress-strain effect in the waveguide located internally in the optical phase modulator.
  • the phase-shifted signal 22 and the second laser pump 7 enters the first waveguide 9, which is a second-order nonlinear waveguide, in the first waveguide 9 a part of the phase-shifted signal 22 and the second laser pump 7 are frequency converted generating the frequency converted signal 10 with frequency f3.
  • the special case of spontaneous parametric down conversion (SPDC) in which two signals with frequencies with f3 and f4 is not included in this drawing.
  • the frequency converted signal may further optically interact with the laser pumps by optical parametrical amplification to generate the modulated frequency converted signal 19, which is the output signal 33 and is outputted through an output port 18.
  • Fig. 2 shows the situation where the first laser pump 6 with the frequency f1 is phase shifted by the first modulator 12’.
  • the optical phase modulator 12’ is placed between the input coupler 4 and the optical combiner 8, so the phase shift of the first pump 6 takes place between the input coupler 4 and the optical combiner 8.
  • Fig. 3 is identically with Fig. 2 except that the first modulator 12’ is positioned to phase shift the second laser pump 7. But otherwise, the embodiment shown in Fig. 3 works the same way as the embodiment shown in Fig. 2 and is therefore not further described here.
  • the working method for the embodiment illustrated in Figs. 2 and 3 is described in the following.
  • the letters A-F illustrates where in the photonic integrated circuit 1 the different processes take place.
  • the laser pumps 6, 7 from the two laser sources 2, 3 are coupled into the photonic integrated circuit 1.
  • the phase of one of the pumps is modulated.
  • - In Fig. 2 it is the first laser pump 6 with frequency f1 that is phase modulated. 83690PC01 19 -
  • Fig. 3 it is the second laser 7 with frequency f2 that is phase modulated.
  • C. The pumps are combined into the first waveguide 9 by the optical combiner 8.
  • D. By difference frequency generation (DFG), or sum of frequency generation (SFG), or second harmonic generation (SHG) a frequency converted signal 10 with frequency f3 is generated from optical interaction of the phase-shifted signal 22 with either the first laser pump 6 (in Fig. 3) or the second laser pump 7 (in Fig. 2) in the first waveguide 9.
  • DFG difference frequency generation
  • SHG sum of frequency generation
  • Figs. 5a and 5b illustrate in a simplified overview the dynamics of an advanced embodiment of the photonic system of the embodiment with a second waveguide. 83690PC01 20 Fig.
  • FIG. 5a and 5b illustrate an of the photonic system of the invention, wherein phase shift of one or more of the first laser pump, second laser pump and/or the frequency converted signal is taking place in the second waveguide.
  • Fig. 5a shows a compact platform 1 which preferably is a photonic chip with an embedded integrated circuit (PIC).
  • the first laser source 2 is generating a first laser pump 6
  • the second laser source 3 is generating a second laser pump 7.
  • the first laser pump 6 and second laser pump 7 enters the nonlinear first waveguide 9.
  • the first laser pump 6 and the second laser pump 7 are frequency converted generating a modulated frequency converted signal 19.
  • One or more of the first laser pump 6, the second laser pump 7 and/or frequency converted signal 10 see Fig.
  • the second waveguide enters the second waveguide 11 as the incoming beam(s) 21, the second waveguide works together with an optical phase modulator 12’’ and a reflector 16 to generate a phase shifted signal 22, which is returned to the first waveguide 9.
  • the phase shifted signal is optical interacting with the first laser pump 6, the second laser pump 7 and/or the frequency converted signal 10 to generate a modulated frequency converted signal 19 which is the output signal 33.
  • a phase shift controller 26 is arranged to control the optical phase modulator 12’’ to regulate the phase shift taking place in the optical phase modulator 12’’ by sending an electric signal 32 to the optical phase modulator 12’’, which either changes the refractive index by an electrical- optical effect or a thermal-optical effect, or by changing the optical path length by inducing a stress-strain effect in the waveguide located internally in optical phase modulator, and hereby causing the phase shift.
  • Fig. 5b is illustrating the dynamics in the same photonic system of fig 5a with a feedback mechanism added, where the output signal 33 is transmitted as a feedback signal 31 to the phase shift controller 26. The phase shift controller 26 then may adjust the phase shift taking place in the optical phase modulator 12’’by changing the electric signal 32.
  • Figs. 6-9 illustrate the embodiment of Figs. 5a and 5b in more detail.
  • Fig 6 shows the compact platform 1, which may be a photonic chip, the first laser source 2 generating a first laser pump 6 with frequency f1, the second laser source 3 generating a second laser pump 7 with frequency f2.
  • the input couplers 83690PC01 21 4, 5 are coupling the first laser 6 and the second laser pump 7 into the optical combiner 8, which may be a multiplexer.
  • An evanescent coupler 20 is arranged to couple one, or more, of the pumps or signal from the first waveguide into the second waveguide as incoming beam(s) 21.
  • the incoming beam(s) 21 from the first waveguide is/are the first laser pump, the second laser pump, and/or the frequency converted signal.
  • the incoming beam 21 is the first laser pump 6 which is phase shifted in the second waveguide 11.
  • an optical phase modulator 12’’ may phase shift the incoming beam or signal 21 generating a phase shifted signal 22, which is returned to the first waveguide.
  • a phase shift controller 26 is arranged to control the optical phase modulator 12’’ to regulate the phase shift taking place in the second waveguide 11 by sending an electric signal 32 (see Fig.
  • the phase shift controller 26 comprises an electrical contact pad 14 with an input port 15.
  • the optical phase modulator 12’’ is controlled by the electrical signal 32, which is transmitted by an electrical wire 13, from the phase shift controller 26.
  • the phase shift controller comprises an electrical contact pad 14 and an input port for electrical signal 15.
  • a second reflector 16 is mounted at the remote end 38 of the second waveguide. When the incoming beam enters the second waveguide, it may travel from the input end 37 towards the remote end 38.
  • the reflector is positioned to reflect the incoming beam and/or the phase shifted signal back through the second waveguide, so the beam or signal is travelling back in 83690PC01 22 the second waveguide and the signal 22 is returned to the first waveguide.
  • the phase shifted signal 22 enters the first waveguide 9 from the second waveguide 11 the phase shifted signal may be moving the opposite direction than the laser pumps 6, 7, moving towards the input end 37, therefore, a first reflector 17 may be positioned at the input end 37 to reflect the phase shifted signal, so it moves in the same direction as the laser pumps.
  • Fig. 7 is identically with Fig. 6 except that Fig.
  • FIG. 7 shows the situation where the second laser pump 7 with the frequency f2 is the incoming beam 21 and is phase shifted in the second waveguide 11.
  • Fig. 8 is identically with Figs. 6 and 7 except that Fig. 8 shows the situation where the frequency converted signal 10 is the incoming beam 21 and is phase shifted in the second waveguide.
  • the working method for the embodiment illustrated in Figs. 6-8 is described in the following.
  • the letters G-O illustrates where in the photonic integrated circuit 1 the different processes take place.
  • the laser pumps 6, 7 from the two laser sources 2, 3 are coupled into the photonic integrated circuit 1 and subsequently combined by the optical combiner 8, after which the pumps are launched into the first waveguide 9.
  • difference frequency generation difference frequency generation
  • FSG sum of frequency generation
  • SHG second harmonic generation
  • a frequency converted signal 10 with frequency f3 is generated from frequency conversion of the first laser pump 6 and the second laser pump 7 in the first wave guide 9.
  • two frequency converted signals and with frequency f3 and f4 are generated from the frequency conversion of the first laser pump 6 and/or the second laser pump 7 in the first wave guide 9.
  • Part of the beams or signals in the first waveguide is coupled into the second waveguide by directional coupling.
  • 83690PC01 23 - In Fig. 6 it is the first laser pump frequency f1 that is primarily coupled from the first waveguide 9 to the second waveguide 11.
  • phase shifted signal it is the second laser pump 7 with frequency f2 that is primarily coupled from the first waveguide 9 to the second waveguide 11.
  • Fig. 8 it is the frequency converted signal 10 with frequency f3 that is primarily coupled from the first waveguide 9 to the second waveguide 11.
  • K. The phase shifted signal is reflected.
  • the phase shifted signal from the second waveguide is coupled back into the nonlinear waveguide.
  • the phase shifted signal is reflected.
  • N The phase shifted signal now has the phase that further enhance or diminish the generation of the modulated frequency converted signal 19 by optical parametric amplification.
  • Fig. 9 is similar to Fig. 6 and is illustrating the situation where a feedback signal 31 is transmitted from the output port 18 via a beamsplitter 35 to the input port 15, where the feedback signal is used to adjust the electrical signal 32 controlling the phase shift.
  • the phase shift controller may use the feedback signal 26 to increase or reduce the phase shift for instance to seek to enhance the feedback signal. This functionality may be implemented in programmable electronics.
  • Fig. 10 shows a diagram illustrating a simulation of the power of the first laser pump, the second laser pump and the output signal at different phase shifts of the 83690PC01 24 first laser pump.
  • the frequency conversion is initiated.
  • the sum 45 of the output powers of the beams and signals are 10 mW.
  • the output power is the power of the beams and signals at the output port 18 when they leave the first waveguide.
  • the phase shift diagram 40 shows the output power at different phase shifts of the first laser pump.
  • the phase shift of the first laser pump is shown on the x- axis.
  • the power at the output port 18 of the modulated phase shifted signal, which is the output signal 19 is close to zero.
  • the power at the output port 18 of the modulated phase shifted signal, which is the output signal 19 is close to 3 mW.
  • the phase shift diagram 40 shows the magnitude of the output signal 19 at different phase shifts of the first laser pump 6.
  • the optimal output signal is achieved when the phase shift is about 270 degrees. This shows that by phase shifting one of the pumps or signals the magnitude of the output signal can be adjusted and by optimal set up of the phase shift the output signal may be enhanced significantly.
  • Fig. 11 illustrates the method of the invention.
  • the method comprises generating (S1) a first laser pump, generating (S2) a second laser pump, coupling (S3) the first laser pump and the second laser pump into an optical combiner, the optical combiner is combining (S4) the laser pumps, and is directing (S5) the combined pumps into the first waveguide.
  • the first waveguide is frequency converting (S6) 83690PC01 25 the first laser pump and the second pump generating a frequency converted signal.
  • the method further comprises generating (S7) one of more phase-shifted signals by phase shifting the first laser pump and/or the second laser pump before the first laser pump and/or the second laser pump enters the optical combiner, and/or by phase shifting the first laser pump after entering the first waveguide, the second laser pump after entering the first waveguide and/or the frequency converted signal.
  • the method is generating (S8) an output signal from the first waveguide.
  • the output signal is a modulated frequency converted signal formed by the first waveguide by optical interaction between the phase-shifted signal pump(s) and one, or more, of the first laser pump(s), the second laser pump and/or the frequency converted signal.
  • DISCLAIMER The following section contains novel theory within the field of integrated optics which underpins the invention.
  • a second-order nonlinear medium e.g. GaAs or Lithium niobate
  • second-order frequency conversion processes can occur, where a signal with frequency ⁇ s is generated.
  • a photonic system for frequency conversion of incoming laser pump(s), the photonic system (100) is comprising: - a first laser source (2), which is arranged to generate a first laser pump (6) at a first frequency f1, - a second laser source (3), which is arranged to generate a second laser pump (7) at a second frequency f2, - a first waveguide (9), which is nonlinear comprising a second-order nonlinear optical susceptibility material for frequency conversion, - an optical combiner (8), which is arranged to combine the laser pumps (6, 7) from the first laser source and the second laser source, and direct the combined pumps into the first waveguide (9), and - an input coupler (4, 5) to couple the first laser pump and the second laser pump, wherein - the first waveguide
  • phase shifting means (11, 12) are a first optical phase modulator (12’), a second optical phase modulator (12’’) and/or a second waveguide (11).
  • phase shifting means (11, 12) are arranged to phase shift the first laser pump (6), the second laser pump (7) and/or the frequency converted signal (10) within the second waveguide (11) to generate phase-shifted signal(s) (22).
  • an evanescent coupler (20) is arranged to couple one, or more, of the beams from the first waveguide (9) into the second waveguide (11) as incoming beam(s), where the incoming beam(s) from the first waveguide is/are: a . the first laser pump (6), b. the second laser pump (7), and/or 83690PC01 30 c . a converted signal (10) which is generated by frequency conversion of the first laser pump and the second laser pump, and - the evanescent coupler (20) is further arranged to couple the phase- shifted signal(s) (22) from the second waveguide into the first waveguide.
  • phase shifting means arranged to phase shift the first laser pump (6), the second laser pump (7) and/or the frequency converted signal (10) within the second waveguide (11) comprises a second optical phase modulator (12’’).
  • phase shifting means arranged to phase shift the first laser pump (6), the second laser pump (7) and/or the frequency converted signal (10) within the second waveguide (11) comprises a second optical phase modulator (12’’).
  • the photonic system according to any of the embodiments E2-E5 wherein the first optical phase modulator (12’) is arranged to phase shift the first laser pump (6) and/or the second laser pump (7) subsequent to being in-coupled and before entering the optical combiner (8).
  • each optical phase modulator (12’, 12’’) comprises a phase shift controller (26) arranged to control the magnitude of the phase shift.
  • phase shift controller(s) (26) is/are adapted to be adjusted based on a feedback signal.
  • arranging the second waveguide (11) to phase shift the incoming beam(s) (21) comprises adapting the refractive index of the second waveguide.
  • the compact platform comprises a photonic chip with embedded integrated circuit(s) (PIC(s)).
  • the first reflector (17) is arranged to reflect the phase-shifted signal(s) received from the second waveguide.
  • the second waveguide (11) comprises an remote end oppositely placed from an input end, where the input end is the end where the incoming beam (21) enters the second waveguide, a second reflector (16) is mounted at the remote end of the second waveguide (11), and the second reflector is arranged to reflect beams propagating within the second waveguide back through the second waveguide to be coupled back into the first waveguide (9).
  • the optical combiner (8) is a multiplexer, being arranged to combine the first laser pump (6) from the first laser source (2) with the second laser pump (7) from the second laser source (3).
  • a method for frequency conversion of incoming laser pumps using a photonic system comprising the steps: - generating (S1) a first laser pump (6) at a first frequency f1, - generating (S2) a second laser pump (7) at a second frequency f2, - coupling (S3) the first laser pump and the second laser pump into the photonic integrated circuit, - combining (S4) the laser pumps (6, 7) by an optical combiner (8), - directing (S5) the combined laser pumps into a first waveguide (9), which is nonlinear comprising a second-order nonlinear optical susceptibility material for frequency conversion, - the first waveguide (9) frequency converting (S6) the first laser pump (6) and the second laser pump (7) generating a frequency converted signal (10) of a third frequency f3, - generating (S7) one or more phase-shifted signal(s) (22) by: 83690PC01 32 ⁇ phase shifting first laser pump (6) and/or the second laser

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

L'invention concerne un système photonique et un procédé de conversion de fréquence de pompes laser entrantes comprenant une première source laser générant une première pompe laser, une seconde source laser générant une seconde pompe laser, un premier guide d'ondes, un second guide d'ondes facultatif, un combinateur optique et un coupleur d'entrée, les guides d'ondes et les combineurs optiques étant intégrés dans une plateforme compacte, la première fréquence de guide d'ondes convertissant les première et seconde pompes laser pour générer un signal converti en fréquence. Des moyens de déphasage sont agencés pour déphaser une ou plusieurs de la première pompe laser, de la seconde pompe laser et/ou du signal converti en fréquence. Le premier guide d'ondes génère un signal de sortie, qui est un signal converti en fréquence modulé par interaction optique dans les premiers guides d'ondes entre les pompes et les signaux progressant dans le premier guide d'ondes.
PCT/EP2025/063293 2024-05-22 2025-05-14 Système photonique et procédé de conversion de fréquence de pompes laser Pending WO2025242515A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2124100B1 (fr) * 2008-05-23 2014-01-08 Fujitsu Limited Dispositif de traitement de signaux optiques
EP3084520B1 (fr) * 2013-12-19 2018-07-04 Danmarks Tekniske Universitet Appareil laser à cascade de mélangeurs de fréquence non linéaire
WO2023016962A1 (fr) * 2021-08-10 2023-02-16 Aarhus Universitet Système optique pour la conversion de fréquence d'un photon unique
US20230105656A1 (en) * 2021-10-05 2023-04-06 Andrew Benedick Manipulating the Optical Phase of a Laser Beam
US11988871B2 (en) * 2021-06-21 2024-05-21 Raytheon BBN Technologies, Corp. Photonic integrated circuit (PIC) radio frequency oscillator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2124100B1 (fr) * 2008-05-23 2014-01-08 Fujitsu Limited Dispositif de traitement de signaux optiques
EP3084520B1 (fr) * 2013-12-19 2018-07-04 Danmarks Tekniske Universitet Appareil laser à cascade de mélangeurs de fréquence non linéaire
US11988871B2 (en) * 2021-06-21 2024-05-21 Raytheon BBN Technologies, Corp. Photonic integrated circuit (PIC) radio frequency oscillator
WO2023016962A1 (fr) * 2021-08-10 2023-02-16 Aarhus Universitet Système optique pour la conversion de fréquence d'un photon unique
US20230105656A1 (en) * 2021-10-05 2023-04-06 Andrew Benedick Manipulating the Optical Phase of a Laser Beam

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