JPH0333835A - Method for driving optical function element - Google Patents

Abstract

PURPOSE:To obtain the optical function element which executes inverter logical operations and memory operations of light input and output and has a degree of freedom in the changing range of the wavelength and light intensity of output light with respect to input light by constituting the element in such a manner that the output light intensity of an inverter characteristic is obtd. with respect to the output light intensity of a photodetector. CONSTITUTION:A source voltage V0 is so set that the current I1 flowing in a semiconductor laser LD in the initial state of the output light intensity Pin=0 attains the oscillation threshold of this laser of above. The current I2 flowing in the detector PD increases and the voltage Vb of the resistor R1 increases if the input light intensity Pin to the photodetector PD is increased successively in this state. The current I1 is decreased by the increase in the voltage Vb and the output light intensity Pout decreases as the voltage V0 does not change. The inverter characteristic is obtd. between the input light Pin and the output light Pout in this way. The optical function element having the degree of freedom in the changing range of the wavelength and light intensity of the output light with respect to the light intensity of the output light with respect to the input light is obtd. in this way.

Description

[Detailed Description of the Invention] [Summary of the Invention] This invention relates to a method for driving an optical functional element that performs optical input/output optical logic and optical storage, which includes: performing optical input/output inverter logic operation and storage operation;
The aim is to provide an optical functional element that has a degree of freedom in changing the wavelength and light intensity of the output light relative to the input light.A photodetector is connected in parallel to a forward biased semiconductor laser, and a resistor is connected in series with the forward biased semiconductor laser. Connect the whole thing between the power supplies, set the power supply voltage so that the semiconductor laser oscillates without applying input light to the photodetector, and set the output light intensity of the inverter characteristics to the human power light intensity to the photodetector. It is configured to be obtained from a semiconductor laser.

(Industrial Application Field) The present invention relates to a method for driving an optical functional element that performs optical logic of optical input/output, optical storage, and the like.

In the field of optical information processing, in recent years there has been a rise in the possibility and demand for the construction of optical signal processing systems with more complex operations, and elements with new optical input/output functions are required as their constituent elements.

[Conventional technology]

There is a self-electro-optical element 5EED that performs inverter operation or optical storage using optical input/output (for example, A, B
, Miller et al., “Novel hyb
rtd optically bistable 5w1
tch:The quantum well 5elf
-electr.

optic effect device'Appl
, Phys, Lett, 45(1)+I July
1984). This means that the i layer is M Q W (Multip
A pin photodiode PD having a Quantum Well structure is connected to a power supply V through a resistor R and reverse biased to obtain output light relative to input light.

The wavelength of the human-powered light is selected near the exciton resonance position when the voltage of the diode PD is zero. When the human power is low, the photocurrent is small, so the diode P'
A power supply voltage is applied to D, which shifts the knee 1-+ ion absorption to the longer wavelength (lower energy) side, and the optical absorption is relatively low. Increasing the optical power increases the photocurrent and decreases the voltage across the diode. This voltage reduction increases absorption as the exciton resonance is restored, which increases the photocurrent and thus becomes regenerative feedback and switching under appropriate conditions. The human power output light characteristic shows a hysteresis characteristic as shown in FIG. 7(b).

In this 5EED, the wavelengths of input light and transmitted light, which is output light, are in principle the same. Furthermore, since the input light itself serves as both an output light source and a processed signal, the range of change in output light intensity is naturally determined by the input light and cannot be changed.

Optical storage also includes a forward-biased laser connected in series with a reverse-biased photodiode (e.g., YohOgaha et al.
al, “New B15table 0ptical
DeviceUsing Sea+tconduct
or La5er Diode” Jpn, J, App
lPhys, Voi, 20. No. 9 Sept.
ember+ 1981). This is shown in Figure 8. L.D.
is a laser diode, PD is a photodiode, Rr
, Rz is a resistance, and -V is a power supply. By applying optical input Pl to the photodiode PD, a photocurrent Ip is generated, causing the laser diode LD to oscillate, a portion of the light Po is received by the photodiode PD, and the resulting photocurrent is fed back to the laser diode LD. This device (BrLD; B15table La5er dio
There is also a hysteresis characteristic between the optical input Pi and the optical output Po0 of de), indicating optical bistability. However, this device uses current and light for feedback, so its operating speed is slow.

[Problem to be solved by the invention]

In this way, in 5EED, the input light and output light have the same wavelength,
There are problems such as the range of change in the output light intensity being determined by the incident light, and there is also a problem that the operating speed of BILD is slow.

The present invention improves these points and provides an optical functional element that performs optical input/output inverter logic operation and storage operation, and has a degree of freedom in changing range of wavelength and light intensity of output light with respect to input light. The purpose is to

[Means to solve the problem]

FIG. 1 shows the configuration of the optical functional device of the present invention. The LD is a semiconductor laser (laser diode) and is forward biased.

PD is a photodetector (photodiode) connected in parallel with the semiconductor laser LD. R, R! is a resistor, and as shown in the figure, LD and R2 are connected in series, PD is connected in parallel to these, and RI is connected in series to all of these. vo is a positive power supply voltage or power supply.

[Effect]

In FIG. 1, the power supply voltage Vo is set so that the current I flowing through the semiconductor laser LD in the initial state of input light intensity Pin=O is equal to or higher than the oscillation darkness value of the laser.

In this state, when the input light intensity Pin to the photodetector PD is increased, the current flowing through the photodetector increases as shown in FIG.
As shown in Figure (b), the voltage vb of the resistor RI is increased. Voltage ■. Since Vb does not change, the current flow decreases as shown in FIG. 2(C) and the output light intensity Pout decreases as shown in FIG. 2(d).

In this way, inverter characteristics are obtained between the input light Pin and the output light PoutO.

In this optical functional element, the output light is not transmitted light of the input light, and the wavelength of the output light is never the same as the wavelength of the input light. Further, the change in the output light with respect to the change in the input light varies depending on the current flow and the value of the resistor R5 through which I2 flows, and the range of change in the output light is not determined by the range of change in the input light. Furthermore, since the feedback is not based on light and current, the operation speed is not slow.

If a photodetector PD with input light intensity Pin vs. photovoltaic current I2 characteristics and optical nonlinearity (hysteresis) as shown in Fig. 3(a) is used, the input light intensity Pin vs. resistance resistance R8 voltage vb, and the same Pin vs. -The characteristics of the current I are as shown in FIGS. 3(b) and 3(C), and the characteristics of the input light intensity Pin versus the output light intensity Pout have hysteresis as shown in FIG. 3(d).

〔Example〕

A normal Pin photodiode is used as the photodiode PD in FIG. 1, R+=470Ω, R2=10Ω, ■.

=20V, and the relationship between input/output light intensity was measured. The results are shown in Figure 4. The inverter characteristics are as shown in FIG. 2(d).

In addition, for the photodetector PD in Fig. 1, a Pin photodiode using MQW in the i-layer is used, and R, = 470Ω.
, Rz=i0Ω, and V0=20V, and the relationship between input/output light intensity was measured by applying a reverse bias to the Pin photodiode. The results are shown in FIG. 5(a).

If other things are the same and R = 410Ω, the characteristics shown in Fig. 5) are obtained. In this way, the output light intensity Pout
The range of variation can be freely changed by changing the resistor R1, regardless of the input light intensity Pin.

Since the current I1 can also be changed by the resistor Rt, the variation range of the output light intensity Pout can be changed only by the resistor R8 or by RI and Rt.

Furthermore, if the input light intensity is changed in a pulse-like manner around the value PinO in the hysteresis loop as shown in FIG. 3(d), the output light intensity Pout can be changed in a rectangular wave-like manner as shown in FIG. . This is a pulse that increases the input light intensity Pin, which is stored as “0,” and a pulse that decreases it, which is stored as “1.”
It can be thought of as ``memory'' and can be treated as inverter memory.

As the photodetector PD, an APD (avalanche photodiode) or the like may be used.

Further, instead of directly flowing the photodetector current I2 to the resistor RI, an amplification element such as a transistor may be interposed.

〔Effect of the invention〕

As described above, according to the present invention, optical inverter operation and optical inverter memory operation are possible, and this new optical functional element can contribute to the development of optical information processing.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is an explanatory diagram of the operation of Fig. 1, Fig. 3 is a characteristic diagram of a nonlinear photodetector, Fig. 4 is a graph showing an actual measurement example of optical inverter operation, Fig. 5 is a graph showing an actual measurement example of optical inverter memory, Figure 6 is an explanatory diagram of optical inverter memory operation, and Figure 7 is 5
An explanatory diagram of EED, and FIG. 8 is an explanatory diagram of BILD. In Figure 1, LD is a semiconductor laser, PD is a photodetector, R,,R. is the resistance and 0 is the power supply. Applicant official stock % formula % nonlinear 7ti day tech special 1 figure 3 figure 7

Claims (1)

[Claims] 1. A photodetector (PD) is connected in parallel to a semiconductor laser (LD) biased in the forward direction, a resistor (R_1) is connected in series to these, and the whole is connected between power supplies, and the photodetector The power supply voltage is determined so that the semiconductor laser oscillates when no input light is applied, and the output light intensity (P_o_u_t) of the inverter characteristic is obtained from the semiconductor laser with respect to the input light intensity (P_i_n) to the photodetector. A method for driving an optical functional element. 2. A photodetector (PD) whose input light intensity (P_i_n) vs. photocurrent (I_2) characteristic has a hysteresis loop is connected in parallel to a forward biased semiconductor laser (LD), and a resistor (R_1) is connected in series with these. The power supply voltage is set so that the semiconductor laser oscillates when no input light is applied to the photodetector, and the power supply voltage increases and decreases in a pulsed manner around the value within the hysteresis loop. A method for driving an optical functional element characterized by adding input light so that the output light intensity of a semiconductor laser has inverter characteristics and memory characteristics at the same time.