JPH06342109A - Optical parts - Google Patents

Abstract

(57) [Summary] [Purpose] To provide optical components with extremely low crosstalk level. [Structure] This optical component comprises one main waveguide 3a and one branch waveguide 3b branched from the main waveguide 3a on the same substrate.
Is formed, a filter (I) 5 that transmits light of wavelength λ ₁ and reflects light of wavelength λ ₂ (λ ₂ ≠ λ ₁ ) is arranged at the branch point 4 of each waveguide, and At the desired location of the branch waveguide, the light of wavelength λ ₁ is blocked and the wavelength λ ₂ (λ ₂ ≠
A filter (II) 7 that reflects the light of λ ₁ ) is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical component incorporated in an optical communication system or an optical sensor system.
The present invention relates to an optical component having an extremely low crosstalk light level.

[0002]

2. Description of the Related Art In an optical communication system or an optical sensor system, communication light of wavelength λ ₁ and, for example, wavelength λ 1
₂ (λ ₂ ≠ λ ₁ ) is incident on the monitor light, and system failures are monitored. As the optical components incorporated in the above system, for example, those shown in FIG. 4 are used. That is, for example, a silica glass clad 2 is formed on a Si single crystal substrate by a flame deposition method and photolithography, and a linear waveguide 3 also made of silica glass is embedded in the clad 2 and the linear waveguide 3 is embedded. 3, a band pass filter 10 having, for example, a dielectric multilayer thin film structure is arranged orthogonal to the longitudinal direction of 3.

Here, the filter 10 has a wavelength λ ₁
Is used, but light having a wavelength λ ₂ (λ ₂ ≠ λ ₁ ) is reflected. For example, an input optical fiber 6a is connected to one end face of this optical component with the linear waveguide 3 with its optical axis aligned, and an output optical fiber 6b is connected to the other end face of the optical waveguide 6b. They are connected with their optical axes aligned.

In this optical component, the wavelength λ ₁ and the wavelength λ _1
When the light of wavelength 2 enters the linear waveguide 3 from the optical fiber 6a and reaches the filter 10, the light of wavelength λ ₁ becomes
The light having the wavelength λ ₂ is reflected by the filter 10 and again propagates through the optical fiber 6a.
It propagates through a and becomes a return light.

[0005]

[Problems to be Solved by the Invention] However, in practice
The filter being manufactured, eg the dielectric multilayer thin described above
In the case of a pass band type filter with a film structure, a certain wavelength (in this case
If λ₁) Light cannot be completely transmitted
Yes, the wavelength is always λ ₁Light of
Cause the reflection of.

Even if the above-mentioned slight reflection of the light of the wavelength λ ₁ occurs, it adversely affects the quality of the optical communication in the present optical communication system. Therefore, in the above-mentioned optical component, it is strongly required to suppress the reflected light level of the light having the wavelength λ ₁ to about 0.1% or less, and more preferably to suppress it to about 0.01% or less.

The present invention has been developed to meet the above-mentioned demands, and an object thereof is to provide an optical component in which the reflected light level when incorporated in an optical communication system is extremely low.

[0008]

[Means for Solving the Problems] To achieve the above object.
Therefore, in the present invention, one main waveguide is provided on the same substrate.
One branch waveguide is formed to branch from the path and its main waveguide
At the branch point of each of the waveguides, the wavelength λ₁Transmitting light
And the wavelength λ₂(Λ₂≠ λ₁) The light reflects
(I) is arranged and a desired portion of the branch waveguide is provided.
Has the wavelength λ₁The light of wavelength λ₂(Λ₂≠ λ
₁) Is equipped with a filter (II) that reflects light.
And the optical component (hereinafter referred to as the first optical component)
Provided, and one lead waveguide and its lead on the same substrate
One branch waveguide branched from the waveguide is formed,
At the branch point of the waveguide, the wavelength λ₁The wavelength of light
λ ₂(Λ₂≠ λ₁) Has a filter (I) that reflects light.
And a wavelength λ at the desired location of the branch waveguide.
₁Light is reflected and has wavelength λ₂(Λ₂≠ λ₁) Through the light
Filter (III) is in the optical axis direction of the branch waveguide.
It is placed diagonally and further behind the filter (III).
Is the wavelength λ₂Is a mirror that reflects the light of
Characterized by being arranged at right angles to the optical axis direction
An optical component (hereinafter referred to as a second optical component) is provided.

[0009]

In the first optical component, when the light of wavelength λ ₁ and the light of wavelength λ ₂ propagate through the main waveguide on the incident side and reach the filter (I) located at the branch point, most of the light of wavelength λ ₂ Is reflected by the filter (I) to change the optical path toward the branch waveguide, and a part of the transmitted light propagates through the main waveguide on the emission side. Then, most of the light of the wavelength λ ₁ passes through the filter (I) and propagates through the main waveguide on the emission side as it is, and a part of the reflected light propagates toward the branch waveguide.

When the light propagating through these branch waveguides reaches the filter (II) arranged in the branch waveguide, the light of wavelength λ ₂ is reflected there and returns to the filter (I) at the branch point again. Since the light is reflected by the filter (I) and returns to the main waveguide on the incident side again, the light can be monitored. On the other hand, when the reflected light of wavelength λ ₁ in the branch waveguide reaches the filter (II), the filter (I
I) returns from the branch waveguide by the amount of blocking attenuation for the light of wavelength λ ₁ and reaches the filter (I), where most of the light passes through the filter (I) and the rest is reflected and propagates through the branch waveguide again. To do.

Therefore, in the first optical component, the level of the reflected light of wavelength λ ₁ monitored by the main waveguide on the input side is reduced by the above-mentioned amount of blocking attenuation as compared with the case where the filter (II) is not present. However, the crosstalk level becomes low.
On the other hand, also in the second optical component, all the light of the wavelength λ ₂ is changed to the branch waveguide, and a part of the light of the wavelength λ ₁ propagates in the branch waveguide as reflected light.

Then, both lights reach the position of the filter (III), and the light of wavelength λ ₂ passes through the filter (III), but is reflected by the mirror and again passes through the filter (III) and is filtered. It reaches (I) where it is reflected and returned to the main waveguide on the incident side for monitoring. On the other hand, the reflected light of wavelength λ ₁ is reflected by the filter (III). And the filter (II
Since (I) is arranged obliquely with respect to the optical axis direction of the branch waveguide, the reflected light of wavelength λ ₁ reflected by the filter (III) does not return to the branch waveguide and is embedded in the branch waveguide. It is radiated toward the existing cladding and disappears there. That is, since the reflected light of wavelength λ ₁ reflected by the filter (I) never returns to the main waveguide on the input side, the crosstalk is practically zero.

[0013]

Examples of the invention

Example 1 A schematic plan view in which an input side optical fiber and an output side optical fiber are connected to a first optical component is shown in FIG. 1, and a sectional view taken along line II-II of FIG. 1 is shown in FIG. In FIG. 2, SiO is formed on a Si single crystal substrate 1 having a length of 20 mm, a width of 5 mm and a thickness of 1 mm.
Consists of _two, the lower cladding layer 2a having a thickness of 20 [mu] m, also made of SiO _2, an upper cladding of thickness 20 [mu] m layer 2
b is formed, and SiO ₂ --Ti
A waveguide core 3 made of O ₂ and having a road width of 8 μm, a road height of 8 μm, and a relative refractive index difference Δ: 0.25% is embedded. In addition,
These clads and waveguide cores can be formed by combining the flame deposition method and the dry etching method.

The plane pattern of this waveguide core 3 is shown in FIG.
As shown in FIG. 5, the main waveguide 3a linearly extends in the longitudinal direction of the substrate, and the branch waveguide 3b branched from the branch point 4 in the main waveguide 3a at a desired angle θ. Here, the angle θ was 14 °. At the position of the branch point 4, a short wavelength band-passing type dielectric having a wall thickness of 20 μm and capable of transmitting light of wavelength (λ ₁ ) 1.3 μm but reflecting light of wavelength (λ ₂ ) 1.55 μm. A filter (I) 5 having a multilayer thin film structure is arranged. At this time, filter (I)
5 is arranged with an inclination of 7 ° with respect to the optical axis direction of the main waveguide 3a.

The branch waveguide 3b has a wall thickness of 20 μm.
m, wavelength (λ ₂ ) 1.55 on one surface of the glass substrate.
A band-stop type dielectric multilayer thin film that reflects light of μm and transmits light of wavelength (λ ₁ ) 1.3 μm is formed as a filter surface, and has a wavelength (λ ₁ ) of 1.3 μm on the back surface. Filter (II) 7 with absorber formed to attenuate light
Are placed. The filter (II) 7 is arranged such that the filter surface is orthogonal to the optical axis direction of the branch waveguide 3b.

When the filters (I) and (II) are arranged, a slit having a predetermined width and a predetermined depth is formed in each of the arranged positions by using a dicing saw, and the filter (I ), (II), and then fix these filters in the slits with an optical adhesive. On both end faces of the main waveguide 3a, as shown in FIG.
μm zero dispersion optical fiber (standard single mode optical fiber) 6
a and 6b were connected as an input side optical fiber and an output side optical fiber, respectively.

In the case of this optical component, the filter (I) used
The crosstalk level at the transmitted light wavelength (λ ₁ = 1.3 μm) is -15 dB, and the blocking light wavelength (λ ₁ = 1.3) of the filter (II).
Since the amount of attenuation in (μm) was 25 dB, even if the loss was ignored, it was an extremely low level of -40 dB (0.01%) as a whole. Example 2 A schematic plan view of a second optical component is shown in FIG. This optical component has the same structure as the first optical component except for the fact that a filter (III) and a mirror which will be described later are arranged in the branching waveguide 3b.

That is, at the position in front of the branch waveguide 3b (on the side of the branch point 4), the wall thickness is 20 μm and the wavelength (λ ₁ ) is 1.
A filter (III) 8 that reflects light of 3 μm and transmits light of wavelength (λ ₂ ) 1.55 μm is arranged. At this time,
The filter surface of the filter (III) 8 is arranged at an angle of 8 ° with respect to the optical axis direction of the branch waveguide 3b. In the branch waveguide 3b, behind the filter (III) 8 (branch point 4
A mirror 9 that reflects light having a wavelength of 1.55 μm is arranged at a position (on the side opposite to the side) orthogonal to the optical axis direction of the branch waveguide 3b.

This mirror 9 can be formed by forming a slit having a width of about 100 μm in the branching waveguide 3b with, for example, a dicing saw, and depositing Ag / Cr thereon, for example. In the case of this optical component, the crosstalk level at the transmitted light wavelength (λ ₁ = 1.3 μm) of the filter (I) used is −
15 dB, reflected light wavelength of the filter (III) (λ ₁ = 1.3μ
The crosstalk level in m) is -25 dB, and the overall crosstalk level is -40 dB (0.0) even if the loss is ignored.
1%), which was an extremely low level.

In the second optical component, in order to change the transmitted light wavelength of the filter (III), a band-pass type filter having a different design is used, or a filter having a dielectric multilayer thin film structure is used. , Its transmittance characteristics are shifted to the short wavelength side according to the incident angle of light, and by arranging band-pass filters of the same design with different tilt angles with respect to the branch waveguide, It may be used as a filter (III).

[0021]

As is apparent from the above description, in the optical component of the present invention, the reflected light level of the communication light having the wavelength λ ₁ becomes extremely low. This is an effect brought about by providing a branch waveguide outside the main waveguide and arranging the filter (II) or the filter (III) and the mirror in the branch waveguide.

Therefore, when the optical component of the present invention is incorporated into an optical communication system, it becomes an optical component having an extremely low crosstalk level, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a first optical component example of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a schematic plan view showing a second optical component example of the present invention.

FIG. 4 is a schematic plan view showing an example of a conventional optical component.

[Explanation of symbols]

 1 Substrate (Si Single Crystal Substrate) 2a Lower Cladding Layer 2b Upper Cladding Layer 3 Waveguide Core 3a Main Waveguide 4 Branching Point 5 Filter (I) 6a, 6b Optical Fiber 7 Filter (II) 8 Filter (III) 9 Mirror

Claims (2)

[Claims] 1. A main waveguide and a main waveguide on the same substrate.
One branch waveguide branched from the waveguide is formed,
At the branch point of the waveguide, the wavelength λ₁The wavelength of light
λ₂(Λ₂≠ λ₁) Has a filter (I) that reflects light.
And a wavelength λ at the desired location of the branch waveguide.
₁The light of wavelength λ₂(Λ₂≠ λ ₁) Light is anti
Characterized by the placement of a filter (II)
Optical components. 2. One main waveguide and the main waveguide on the same substrate.
One branch waveguide branched from the waveguide is formed,
At the branch point of the waveguide, the wavelength λ₁The wavelength of light
λ₂(Λ₂≠ λ₁) Has a filter (I) that reflects light.
And a wavelength λ at the desired location of the branch waveguide.
₁Light is reflected and has wavelength λ₂(Λ₂≠ λ ₁) Through the light
Filter (III) is in the optical axis direction of the branch waveguide.
It is placed diagonally and further behind the filter (III).
Is the wavelength λ₂Is a mirror that reflects the light of
Characterized by being arranged at right angles to the optical axis direction
Optical components.