JPS63157108A - Optical dividing and combining circuit - Google Patents

Abstract

PURPOSE:To improve the assembly operability by allowing all waveguide ends to face once side edge of a substrate, providing a groove on a branch part and providing a partial transmitting and reflecting filter in the groove, and also, providing an optical reflecting body on a turning-back part. CONSTITUTION:All waveguide ends of an input and an output are allowed to face one substrate side edge 1a. On the surface of a substrate 1, a groove 7 for parting the waveguide is carved and provided, and in this groove 7, an interference filter 8 is fitted and installed. In this constitution, when mixed light beams whose wavelengths are, for instance, 0.85mum and 1.3mum are made incident on an input path 2, the light beam whose wavelength is 0.85mum is led to a reflected light waveguide 3 by the filter 8, and the light beam whose wavelength is 1.3mum is led to a transmission light waveguide 4. The light beam propagated through this waveguide 4 reaches a turning-back part 5 and reflected by a reflecting body 10, propagated as it is in a waveguide 4b, transmits through an interference filter 9, and thereafter, emitted from the waveguide end of the side edge 1a and made incident on an optical fiber 11c. The light beam reflected by the filter 8 is made incident on an optical fiber 11b. In such a way, the assembly operability is improved, and also the assembly work can be executed easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical splitting/combining circuit used to split or combine transmitted light according to wavelength or power.

[Description of prior art]

Conventionally, a waveguide-type light splitting/combining circuit with a structure shown in the figure is known (for example, IEICE Technical Report 0QElr!
-29, JP-A-1-/9r'lOl', etc.).

In the figure, a 5i02-TiO2 optical waveguide 27. is placed on a substrate 81. A RA-2RF was formed to protrude linearly, the waveguide was divided at each branch part in the circuit, and an interference filter, 29 a-j 9 G, was interposed at this divided part, and it was installed upright on the board. The filter is held by the filter guide and groove.

The above filter is inclined so that its surface normal bisects the angle formed by the optical axes of both branch paths.

Furthermore, the ends of each waveguide end inside the side edge of the substrate, and at the ends of these waveguides, optical fiber guides 30a to 30e provided on the substrate sandwich and fix optical fibers 2ta.
-26,e is connected.

In the above circuit, when mixed light of four different wavelengths is input to the waveguide 27, the propagating light passes through the interference filter 2 of the first branch.
At wave a, the light is split into transmitted light and reflected light according to the wavelength selection characteristics of the filter, and the transmitted light propagates through the waveguide 2J'a and reaches the interference filter 29b at the second branch. ,
The specific wavelength light transmitted through this filter is passed through the optical fiber J4C.
Output to and filter! The light of the other wavelength reflected by the optical fiber 9b is output to the optical fiber 21,b. Further, the light reflected by the first filter 29a propagates through the waveguide 2rC1 and passes through the third filter.
reaches the interference filter 2qC at the branching part of , and a part of the light passes through the filter and propagates through the waveguide if, and then the light 7 ipaco≦
After the light output to e and reflected by the filter 29C propagates through the waveguide 2re, the light 7aipa, ! 6d.

In this way, the input optical fiber 24a is passed through the waveguide, ! The mixed light of four wavelengths incident on the optical fiber 7 is divided into light of each wavelength and is passed through the optical fiber 2≦b, 260.

,? They are output to gd and 2te, respectively. Also, waveguide 2
When light of each wavelength propagates reversely through IrC 1rb and 2IrC, these transmitted lights merge into waveguide 2ra.

The light propagating through 2td merges into waveguide 27 through filter j9alc.

In this way, the circuit functions as a demultiplexing/multiplexing circuit that divides mixed light of two different wavelengths into each wavelength, or combines the lights of each wavelength. Further, another example of a conventional demultiplexing and multiplexing circuit (for example, Japanese Patent Application Laid-open No. 4/1983-61 Otsu 02) is shown in Fig. @5.

In this example, one substrate 3rK, waveguide 32°33.3
waveguides 32 and 33 are arranged symmetrically and inclined with respect to the normal to the side edge of the substrate, and both ends are connected at the side edge, and waveguide 3≠ is parallel to waveguide 33. The connecting portion between the waveguides 32 and 33 and the waveguide 3
An interference filter film 3j that transmits (or reflects) light of a specific wavelength and reflects (or transmits) light of other wavelengths is provided on the side edge of the substrate where the end of ≠ is exposed, and the above-mentioned waveguide is further provided. A transparent spacer 36 is bonded to the side edge of the substrate, and a reflective film 37 is provided on the side edge of the spacer 360.

In the above circuit, for example, two wavelengths λ1. When the mixed light of λ2 is made to enter the waveguide 32, the light of the wavelength λ1 of the propagating light is reflected by the filter film 3 and enters the waveguide 33, and the light of the wavelength λ2 is transmitted through the filter film 33. After being reflected by the reflective film 37 and transmitted through the filter film 35 again, the light enters the waveguide 3≠, and the lights with wavelengths λ1 and λ2 can be taken out from the waveguides 33 and 3≠, respectively.

Conversely, the light of wavelength λ1 is sent to the waveguide 33, and the light of wavelength λ1 is sent to the waveguide 33.
If light with a wavelength λ2 is made incident on each of the wavelengths ≠, a mixture of these two wavelengths can be extracted from the waveguide 32.

[Problem that the invention seeks to solve]

In the structure shown in Fig. t1, components such as an optical 7-eyeper that is read directly at the end of the waveguide for inputting and outputting light are distributed around the board and are arranged at different angles, so that the circuit is When assembled into a device, the waveguide circuit board requires a large installation space and the assembly process becomes complicated.

In addition, in the conventional structure shown in FIG. 5, the thickness of the spacer 36 must be precisely processed to match the positional relationship between the connecting portion of the waveguides 32 and 33 in contact with the interference filter film 3j and the end of the waveguide 3g. Furthermore, since it requires bonding to a waveguide circuit board, it is time-consuming to manufacture, making it unsuitable for mass production.

[Means for solving problems]

The splitting and merging circuit of the present invention that solves the above problems is provided with a branching part and a folding part for folding back one of the branched waveguides in an optical waveguide circuit formed on a substrate, so that all waveguide ends are connected to the substrate. A groove for dividing the waveguide was provided in the branch part facing one side edge of the waveguide, a partially transmitting reflection filter was interposed in the groove, and a light reflector was arranged in the folded part.

[For production]

The light propagating through the waveguide is split in wavelength or power into transmitted light and summer radiation by a filter in the branching section, and after propagating through the branching section, the split light is reflected by a reflector at the folding section and remains as it is. Propagates in a folded waveguide,
After repeating the above-mentioned branching and reflection folding, which are provided in multiple stages as necessary, all of the propagating lights are taken out from the output end, which is arranged along with the input end on one side edge of the substrate.

〔Example〕

The present invention will be described in detail below based on embodiments shown in the drawings.

In Figure 1, l is a substrate made of a transparent plate made of glass, synthetic resin, etc., and an optical waveguide consisting of a region with a higher refractive index than the surrounding area is embedded in this substrate l by a method such as a two-step ion exchange method. It is.

The optical waveguide has an input path 2, a reflective optical waveguide 3 branching from the input path λ at a certain angle (for example, 200 degrees), and a transmission optical waveguide ψ extending from the input path, The transmitted light waveguide ψ has a folded part j that is folded back toward the incident i side near the side edge /b of the substrate, and at this folded part j, the corner part of the waveguide is exposed at the substrate side edge lbK, and around the folded part 5 The incident path tIa and the reflection path dab are at the substrate side edge lb.
The optical axis is symmetrically inclined at a constant angle (for example, 100) with respect to the surface normal of the lens, forming a substantially V-shape.

The reflected light waveguide 3 and the transmitted light waveguide 3 form a curved part near the end of the substrate side edge/a.
The optical axis is perpendicular to the substrate side edge /aK within a certain distance from the optical axis.

In addition, the end of the waveguide for input and output is made to face the side edge /a of one of the substrates. On the surface of the substrate, there is a groove 7 that divides the waveguide at the waveguide branching portion 6 at the side edge /a of the substrate.

/b is engraved parallel to K and over the entire width of the board, and the branch part B in this groove 7 transmits (or reflects) light of a specific wavelength and reflects light of other wavelengths (or ?j An interference filter (r) is fitted in which the waveguides 2 and 3 are inclined so that the normal to the surface of this filter bisects the angle formed by the input path and the reflective optical waveguide 3. . -Groove 7 as an example
The width is jOμm.

A filter t polished and thinned to a depth of 200 μm and a thickness of 170 μm is inserted and fixed with an ultraviolet curing optical adhesive. Further, a specific wavelength bandpass filter 9 for cutting noise light in the propagating light is fitted in the groove 7 at a location where the transmitted light waveguide is divided.

For example, a filter! is a long-wavelength pass filter that transmits light with a wavelength of 7 μm or more, which is made by alternately laminating 5i02 films and TiO2 films, and a band-pass filter having a center transmission band of 3 μmK wavelength is used as filter 9. Also, the side edge of the substrate where the folded part j of the filter-transmitted optical waveguide is exposed/
A light reflector 10 is placed at b. For this reflector 10, a deposited film of Ou, Ag, etc. or an interference filter can be used, and in the case of a Cu film with a thickness of 50X, the wavelength is 3 μm and 9
A reflectance of 6% is obtained. and an input path 2, and output paths 3 for each of the reflected light and the transmitted light. At the end of the group b, there is an optical fiber //a,
//b.

Connect Ilo.

FIG. 2 shows another embodiment of the invention.

The difference between this example and the one in FIG. 1 is the folded portion of the filter-transmitting optical waveguide! is located inside the side edge tb of the substrate, and another direction /2 is carved in parallel to the groove 7 so as to cut the corner of this folded part S, and at the position of the folded part j in this groove 12. A thin plate-shaped light reflector IO is fitted and fixed with an ultraviolet curing optical adhesive or the like.

In the circuits shown in Figures 1 and 2, for example, when mixed light of two wavelengths o, rsμm and/or 3μm is input to the input path λ, most of the light with wavelengths o and rrμm is reflected by the interference filter r. is guided to the reflected light waveguide 3, and the wavelength /,
Most of the light of J μm is transmitted and guided to the transmitted light waveguide. The light with a wavelength of /, Jμm propagating through this waveguide reaches the folded part 5 of the waveguide, is reflected by the reflector 10, propagates as it is in the waveguide b after the folded part, and is transmitted through the filter. After that, the light exits from the waveguide end of the substrate side edge /a and enters the light at 7 eye per/10K. The 58 m wavelength light O1 reflected by the filter r is emitted from the waveguide end on the substrate side edge /a and enters the light 7 eyeper//b.

When we measured the insertion loss using the above circuit, we found that the wavelength o
, rsttm channel At'O, jd13. wavelength/,
It was IC1B in the 3 μm channel. The breakdown is as follows: 007dB is the loss due to the filter fitting groove 7, and 0.2C
IB is the loss due to the input path 2 and the filter-reflecting optical waveguide 3, O, J (iB is the loss due to the input path 2 and the filter-transmitting optical waveguide l
This is a loss due to IK.

Further, the far end crosstalk attenuation was 30 dB or more.

FIG. 3 shows another embodiment of the invention.

In this example, there are three branch parts 6a + 6b in the waveguide circuit.
rd0 and three folded parts ja, jb, and jc are provided, and in one groove 7 passing through these three branching parts, one type of interference filter ra, lr having a wavelength selection characteristic of 5% is provided.
b.

IQ and rd are fixed at intervals. The circuit pattern consists of a reflector 1 after passing through the first stage filter and ra.
The light reflected at 0 and traveling along the return path is passed through the second stage filter rb.
The transmitted light of this filter is emitted to the optical fiber //C through the first folding path, and the reflected light is guided to the reflector 10 by the second-stage filter reflection waveguide, and the reflected light is guided to the reflector 10 by the second-stage filter reflection waveguide. The filter tOK is guided, and the transmitted light of this filter rc is emitted to the optical fiber //d through the waveguide, and the reflected light is guided to the reflector io through the third-stage reflective optical waveguide and propagated through the third-stage folded path. Filter, 1'(
After transmitting the light 1, the light is emitted to the optical fiber //e.

In the above circuit, for example, 17 types of wavelength 0 are input to the input path.
．． 71rlLm, 0. ! #μm, /, 2μm
, /, When mixed light including light of 3/1 m is incident, the first
If the stage filter Ira is set as a long wavelength bass filter that transmits light with a wavelength longer than the wavelength Oi around 2 μm, it will be 0.7 rμ.
Only the m wavelength light is reflected and outputted from the optical fiber/rbVc, and the remaining wavelength light that has passed through the filter ra reaches the second stage filter C0Jrμm bandpass filter)tb, where the o and rrμm wavelength light passes through the filter. and outputs it to an optical fiber/rC.

In addition, the mixed light of 82 μm and 83 μm reflected by filter rb reaches the third stage filter (7.2 μm band pass filter) rC, where the light of 8 μm passes through filter rC and is connected to optical fiber lrd. The 83 μm light emitted from the filter IC and reflected by the filter IC passes through the 8th stage filter
After the noise light is cut by the bandpass filter (bandpass filter) rd, it is emitted to the optical fiber /♂e.

Although the present invention has been described above regarding a duplexer, it goes without saying that the circuit of the present invention can also be used as a multiplexer or a bidirectional multiplexer/multiplexer.

Further, by using a partially transmitting/reflecting filter without wavelength selectivity as a filter, it can also be used as a branch/combiner circuit.

〔Effect of the invention〕

According to the present invention, by folding back one of the waveguides branching from the branch part, all the waveguide ends are exposed to one side edge of the substrate. Using the 7-eyebar array, all waveguide ends can be connected simultaneously, greatly improving assembly workability.

Furthermore, when it is incorporated into a device, it requires only a small space.

In addition, the direction change of branched propagation light to concentrate the input and output ends on one side of the substrate is performed while passing through the waveguide, making assembly easier than the conventional transparent spacer added type mentioned above. , and the waveguide circuit is well-known 7)
Since it can be patterned with high precision using IJ lithography technology, a light splitting/combining circuit with low loss and stable quality can be obtained.

[Brief explanation of the drawing]

8F17 is a plan view showing the seventh embodiment of the present invention, Fig. 1 is a plan view showing the second embodiment of the invention, Fig. 3 is a plan view showing the third embodiment of the invention, FIG. 3 is a plan view showing an example of a conventional dividing and merging circuit, and FIG. 3 is a plan view showing another example of the conventional circuit. l... Board 2... Song input path 3...
Filter reflection optical waveguide...Filter transmission optical waveguide! ...Turning section 6... Branching section 7,
/ Ko... Groove! , Wa... Filter 10.
...Light reflector //a, /lb, //C...
Opening fiber 1 [Go? , 1 Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) In the optical waveguide circuit formed on the substrate, a branch part and a folding part for folding back one of the branched waveguides are provided so that all the waveguide ends face one side edge of the substrate, and the branch part 1. A light splitting/combining circuit characterized in that a groove is provided to divide a waveguide, a partially transmitting/reflecting filter is interposed in the groove, and a light reflector is disposed in the folded portion. (2) The waveguide corner of the folded portion is located inside the side edge of the substrate, a groove passing through the corner is formed in the substrate, and a light reflector is fitted in the groove. A light splitting/combining circuit according to scope 1. (3) The light splitting/combining circuit according to claim 1, wherein the waveguide corner of the folded portion is exposed at the side edge of the substrate, and a light reflector is provided in contact with this exposed surface.