WO2003058305A1

WO2003058305A1 - Optical transmission/reception module of optical waveguide type, and substrate for making the same

Info

Publication number: WO2003058305A1
Application number: PCT/JP2002/013666
Authority: WO
Inventors: Tooru Takahashi; Nobuo Miyadera
Original assignee: Hitachi Chemical Co., Ltd.
Priority date: 2001-12-28
Filing date: 2002-12-26
Publication date: 2003-07-17
Also published as: JPWO2003058305A1; JP3799611B2; AU2002367342A1

Abstract

An optical transmission/reception module of optical waveguide type comprising a substrate and optical elements formed thereon, wherein optical crosstalk reducing means is provided to the substrate. An optical transmission/reception module of optical waveguide type comprising a lower clad layer, a core layer, an upper clad layer for embedding the core layer, a light receiving element and a light emitting element, wherein the width of the clad layer adjacent to the core layer at least in the vicinity of the light emitting element is three to five times the width of the core layer. A substrate for making an optical transmission/reception module of optical waveguide type, wherein optical crosstalk reducing means is provided. The optical transmission/reception module of optical waveguide type can significantly reduce optical crosstalk and significantly suppress degradation of reception sensitivity. Since the optical crosstalk reducing means is provided to the substrate, the manufacturing is easy as compared with the conventional way in which optical crosstalk reducing means is provided to the optical elements on the substrate.

Description

Optical waveguide type optical transceiver module and substrate for manufacturing the module

The present invention relates to an optical waveguide type optical transmission / reception module and a substrate for manufacturing the module, and in particular, a so-called optical crosstalk in which transmission light leaks into a light receiving element of the same module to become a noise component and a minimum light receiving sensitivity is reduced. The present invention relates to an optical waveguide type optical transceiver module and a substrate for manufacturing the module. Background art

With the spread of personal computers and Internet networks in recent years, the demand for information transmission is rapidly increasing. For this reason, it is desired that optical transmission with a high transmission speed be spread to terminal information processing devices such as personal computers. In order to realize this, a small-sized optical transceiver module that integrates the transmission function and the reception function using a high-performance optical waveguide etc. for the optical connection is used inexpensively and in large quantities. Need to be manufactured.

In an optical transceiver module, an LD (Laser Diode) element for transmission and a PD (P hoto Diode) element for reception are integrated in one optical transceiver module. In an optical transmitter / receiver module that performs simultaneous transmission and reception, LD light that is not coupled to the optical waveguide core leaks to the PD element for reception as light leakage, and this light leakage component becomes a noise component of signal light, and the optical transmission / reception module Reception sensitivity is reduced.

Until now, various types of optical transmitting and receiving modules have been proposed in which the so-called optical crosstalk in which the light leakage component is transmitted as a noise component of the signal light to the PD device for reception is reduced. Is complicated, or it cannot be said that optical crosstalk can be sufficiently reduced. Disclosure of the invention

Accordingly, it is an object of the present invention to provide an optical waveguide type optical transmitting / receiving module with reduced optical crosstalk.

Another object of the present invention is to provide a substrate for producing an optical waveguide type optical transmission / reception module with reduced optical crosstalk. The present invention provides the following optical waveguide type optical transmitting / receiving module and a substrate for manufacturing the module.

1. An optical waveguide type optical transceiver module including a substrate and an optical element formed on the surface thereof, wherein the substrate is provided with an optical crosstalk reducing means.

2. The optical waveguide type optical transceiver module according to the above item 1, wherein the optical crosstalk reducing means includes means for absorbing and / or blocking light leakage or changing the optical path of light leakage.

3. The optical waveguide as described in 1 above, wherein the optical crosstalk reduction means scatters light leakage by roughening the back surface and / or the surface of the substrate, thereby preventing the light from entering the light receiving element. Type optical transceiver module.

4. The optical waveguide type optical transceiver module according to the above item 3, wherein the degree of surface roughening is JIS Rmax 6 to l2 lm.

5. The optical waveguide type optical transmission / reception module according to the above item 1, wherein the optical crosstalk reducing means is a metal, ceramics, resin, or a combination of two or more of these opaque at the wavelength used.

6. An optical waveguide type optical transceiver module using a multiplexing / demultiplexing filter, wherein the optical crosstalk is within 5 dB. 7. In an optical waveguide type optical transceiver module including a lower cladding layer, a core layer, an upper cladding layer in which the core layer is embedded, a light receiving element, and a light emitting element, at least the core layer near the light emitting element An optical waveguide type optical transceiver module, characterized in that the width of the cladding layer adjacent to the optical waveguide is 3 to 5 times the width of the core layer.

8. The optical waveguide type optical transceiver module according to the above item 7, wherein the surface of the cladding layer configured to be 3 to 5 times the width of the core layer is coated with a light-impermeable material.

9. The optical waveguide type optical transmission / reception module according to the above item 8, wherein the light impermeable material is a metal or a resin.

10. A substrate for producing an optical waveguide type optical transmission / reception module, comprising an optical crosstalk reducing means.

11. The substrate for producing an optical waveguide-type optical transceiver module according to 10 above, wherein the optical crosstalk reducing means includes means for absorbing and / or blocking light leakage or changing an optical path of light leakage.

12. The optical crosstalk reducing means according to the above item 10, wherein the optical crosstalk reduction means scatters light leakage by roughening the back surface and / or the surface of the substrate, and prevents the light from entering the light receiving element. Substrate for making optical waveguide type optical transceiver module.

13. The substrate for producing an optical waveguide type optical transceiver module according to 12 above, wherein the degree of surface roughening is JISR max 6 to l 2 m.

14. The optical waveguide-type optical transceiver module according to 10 above, wherein the optical crosstalk reducing means is a substrate made of metal, ceramics, resin, or a combination of two or more of these materials opaque at the wavelength used. substrate. BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows the present invention provided with an optical crosstalk reduction means with a sloped side surface of the substrate. 3 is a drawing showing an example of the optical waveguide type optical transceiver module of FIG.

FIG. 2 is a plan view showing an embodiment of an optical waveguide type optical transmission / reception module of the present invention provided with an optical crosstalk reduction means.

FIG. 3 is a sectional view taken along line AA of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, optical crosstalk means that when the electric crosstalk (dBm) is so small that it does not matter, the light emitting element is not operated after the optical element (light emitting element, light receiving element, filter) is mounted. The difference between the light receiving sensitivity (dBm) of the light receiving element when operating and the light receiving sensitivity (dBm) of the light receiving element when the light emitting element is operated.

An optical waveguide type optical transceiver module according to the present invention is characterized in that an optical element is provided on a substrate, and the substrate is provided with optical crosstalk reducing means.

The optical waveguide type optical transceiver module of the present invention is preferably provided with a lower cladding layer, a core layer, an upper cladding layer for embedding the core layer, a light receiving element, and a light emitting element on a substrate. .

More specifically, the optical waveguide type optical transmitting / receiving module of the present invention includes, as a substrate, an inorganic material such as glass and quartz; a semiconductor such as silicon, gallium arsenide, aluminum and titanium; and a metal material such as polyimide and polyamide. An optical element such as an optical waveguide, an optical multiplexer, an optical demultiplexer, an optical attenuator, an optical diffractor, or the like is formed on these substrates by using a polymer material or a material obtained by compounding these materials. Optical amplifiers, optical interferometers, optical filters, optical switches, wavelength converters, light-emitting elements, light-receiving elements, or composites of these, and at least optical waveguides, light-emitting elements, and light-receiving elements It has.

A semiconductor element or a metal film other than the light-emitting element and the light-receiving element may be formed on the above-described substrate. A silicon film may be formed, or a film of silicon nitride, aluminum oxide, aluminum nitride, tantalum oxide, or the like may be formed. The first example of the most typical optical waveguide type optical transceiver module of the present invention is

, A silicon substrate, on which a polymer optical waveguide, a light emitting element and a light receiving element are mounted. More specifically, a silicon dioxide layer for protecting the substrate and adjusting the refractive index is provided on the upper surface of the silicon single crystal substrate, and the polymer optical waveguide laminate is formed thereon. A typical polymer optical waveguide laminate includes a silicon substrate, an organic zirconium compound layer, a fluorine-free resin layer, a lower cladding layer, a core layer, and a core layer formed on an upper silicon dioxide layer. It has a structure in which an upper cladding layer to be embedded and a protective layer are laminated in this order. The lower cladding layer, the core layer and the upper cladding layer are all formed of a polyimide resin containing fluorine, and the organic zirconium compound layer and the resin layer containing no fluorine serve to improve the adhesion between the substrate and the lower cladding layer. Are arranged to enhance. Next, the optical crosstalk reducing means provided on the substrate of the present invention will be described.

Preferred examples of the optical crosstalk reducing means provided on the substrate of the present invention include the following means.

1. Rough light is scattered by roughening the back surface and / or the surface of the substrate to prevent the light from entering the light receiving element.

2. The side surface of the substrate, which is usually formed in a direction perpendicular to the plane of the optical waveguide, is inclined at preferably 1 ° to 60 °, more preferably 2 ° to 45 ° with respect to the vertical direction. By doing so, it is possible to prevent light leaked from the inclined surface from being incident on the light receiving element. At this time, the inclined surface may be provided on the light emitting element side, or may be provided on the light receiving element side. Good, or both. When both are provided, the inclination angles may be the same or different, and accordingly, the inclination directions may be the same direction or opposite directions.

3. Provide a non-reflective coating layer or a light-absorbing layer on the front surface and / or back surface of the substrate to prevent light leakage from being absorbed by the non-reflective coating layer or the light-absorbing layer and entering the light receiving element.

4. The substrate is made of a material consisting of metals, ceramics, resins, and combinations of two or more of them that are opaque at the wavelength used. Hereinafter, the optical crosstalk reduction means will be described in more detail. The first method is to roughen the back surface and / or front surface of the substrate to scatter light leakage and prevent the light from entering the light receiving element. For example, polishing with sandpaper with a particle size of # 100, treatment with a laser beam, or treatment with ion etching so that the surface roughness JIS Rmax is about 6 to 12 / m I just need. When the surface roughness JIS Rmax is out of the range of 6 to 12 / m, light leakage is not sufficiently scattered and it is difficult to completely prevent light leakage from entering the light receiving element. . Preferably, the roughening is performed on the entire back surface or the front surface or both. The second method is to tilt the substrate side surface of the optical waveguide, which is usually formed perpendicular to the optical waveguide plane, preferably by 2 ° to 45 ° with respect to this vertical direction, In order to prevent the light reflected on the inclined surface from entering the light receiving element, a desired inclined surface can be obtained when dicing a large number of optical devices formed on a substrate and separating them into individual optical devices. Use a blade of a specific shape as described above, or perform processing such as cutting and polishing on the vertically formed side surface to obtain a desired inclined surface. You may. As described above, the inclined surface may be provided on the light emitting element side, the light receiving element side, or on both sides. When both are provided, the inclination angles thereof may be the same or different. Therefore, the inclination directions may be the same direction or opposite directions. For example, the slope

As shown in FIG. 1A, the substrate 1 may be inclined inward from the front surface (the surface on which the optical element is mounted) toward the back surface, and conversely, from the front surface of the substrate 1 as shown in FIG. 1B. It may be inclined outward toward the back. The third method is to provide a non-reflective coating layer or a light-absorbing layer on the front surface and / or the back surface of the substrate, and to absorb light leaked by the non-reflective coating layer or the light-absorbing layer to the light receiving element to prevent the incident is on the front or rear surface or both of the substrate, the _{S i 0 2, M g F} 2, T a 2 0 5, T i 0 -reflective coating layer, such as a _2, a vacuum deposition It may be formed by electron beam evaporation or the like, or a light-absorbing resin such as epoxy, polyamide, polyimide or the like may be dissolved in a suitable solvent, applied, and dried. These non-reflective coating layers or light-absorbing layers may be a single layer or a multilayer, or may be formed by combining a plurality of layers.

The thickness of the antireflection coating layer is appropriately determined depending on the wavelength of the light used, but is usually preferably about 0.1 to about I0 m.

The thickness of the light-absorbing layer is preferably from 0.3 to 10 m, for example, about 0.5 / m. In the fourth method, the substrate is made of an opaque metal at the wavelength used, for example, aluminum, copper, chromium, titanium, etc., ceramics, resin, for example, polyimide, epoxy, polyamide, phenol resin, urethane, etc., and It is composed of a material consisting of a combination of two or more of these. By configuring the substrate with a material that is opaque at such wavelengths used, it is possible to effectively attenuate the propagation of light leakage within the substrate. A second example of the most typical optical waveguide type optical transmission / reception module of the present invention is shown in FIG. 2, in which a silicon substrate 1 and a polymer optical waveguide (lower cladding layer) 2, a core layer 3, an upper cladding layer 4), a light emitting element 5, a light receiving element 6, and a multiplexing / demultiplexing filter 7. More specifically, a silicon dioxide layer for protecting the substrate and adjusting the refractive index is provided on the upper surface of the silicon single crystal substrate, and the polymer optical waveguide laminate is formed thereon. A typical polymer optical waveguide laminate includes a silicon substrate 1, an organic zirconium compound layer, a fluorine-free resin layer, a lower cladding layer 2, a core layer 3, The upper clad layer 4 in which the core layer 3 is embedded and the protective layer are laminated in this order. The lower cladding layer 2, the core layer 3, and the upper cladding layer 4 are all formed of a polyimide resin containing fluorine, and an organic zirconium compound layer and a resin layer containing no fluorine are bonded to the substrate 1 and the lower cladding layer 2. It is arranged to enhance the performance.

Next, the optical crosstalk reducing means provided in the optical waveguide type optical transceiver module according to the second embodiment of the present invention will be described.

As shown in FIGS. 2 and 3, the optical crosstalk reducing means provided in the optical waveguide type optical transceiver module of the second embodiment of the present invention comprises at least an upper part adjacent to the core layer 3 near the light emitting element 5. The structure is characterized in that 111 of the cladding layer 4 is configured to be 3 to 5 times the width L ₂ of the core layer 3.

In width 1 ^ 3 times less than the upper cladding layer 4 having a width L ₂ is the core layer 3, may waveguide loss is increased, in 5-fold greater, is insufficient optical crosstalk reduction effect. In the present invention, preferably, the surface of the clad layer configured to be 3 to 5 times the width of the core layer is coated with a light-impermeable material. Such a light-impermeable material Examples of such a layer include a layer of a metal such as aluminum, chromium, nickel, and titanium, and a layer of a resin such as polyimide and polyimide that do not contain fluorine. The thickness of the metal layer is preferably about 0.05 to 1.0 m, and these can be formed by vapor deposition, sputtering, or the like. Further, the thickness of the resin layer is preferably 1.0 / m or more, and usually 3 to 10 zm. The resin is more preferably dyed with a black pigment or dye. The present invention relates to an optical waveguide type optical transceiver module including a lower clad layer, a core layer, an upper clad layer in which the core layer is embedded, a light receiving element, and a light emitting element, wherein at least the core layer near the light emitting element is provided. The width of the adjacent cladding layer is set to be 3 to 5 times the width of the core layer. A typical method of forming the layer is as follows.

First, a lower clad layer, a core layer, and an upper clad layer for embedding the core layer are formed on a substrate, and the upper clad layer, preferably, the upper clad layer and the lower clad layer are formed by, for example, dry etching, wet etching, or the like. It is removed by a method such as etching, laser ablation, milling, or sandblasting until at least the width of the cladding layer adjacent to the core layer near the light emitting element becomes 3 to 5 times the width of the core layer. I just need.

After removing the unnecessary upper cladding layer, the surface of the cladding layer configured to be 3 to 5 times the width of the core layer may be coated with the above-described light-impermeable material, if necessary.

Example 1

Organic zirconium chelate is applied on a silicon wafer by spin coating to a dry film thickness of 100 Å, and after drying, contains fluorine No polyimide resin is applied to a dry film thickness of 0.3 zm, and after drying, a lower cladding layer (8 / m) and a core layer (6.5 m) composed of fluorine-containing polyimide resin are formed. did. Next, a silicon-containing resist is applied to the core layer to a thickness of 0.5 μm, dried, exposed and developed through a mask having a core layer pattern, and reactive ions are formed using the resist pattern as a mask. Etching was performed to form a core layer. After stripping the resist, an upper cladding layer (15 / m) and a protective layer (3 μm) made of a polyimide resin containing no fluorine were formed to form a polyimide optical waveguide. After that, the surface of the silicon wafer on which the optical waveguide was not formed (the back surface of the substrate) was roughened with a water-resistant vapor equivalent to JIS # 1000 to a roughening degree of JIS Rmax 9.6 m. After that, the chip was cut out by dicing, the light receiving element and the light emitting element were attached, and the optical crosstalk of the optical waveguide was evaluated. Comparative Example 1

In the same manner as in Example 1, a polyimide optical waveguide was prepared. After that, without roughening the surface of the silicon wafer where the optical waveguide is not formed (the back surface of the substrate), the chip is cut out into chips by dicing, the light receiving element and the light emitting element are attached, and optical crosstalk of the optical waveguide is reduced. evaluated.

As a result, the optical stress of the module of Example 1 of the present invention in which the back surface of the substrate was roughened was clearly improved as compared with the module of Comparative Example 1. Example 2

Organic zirconium chelate is dried on a silicon wafer by the Sincoat method and dried to a thickness of 100 Å.After drying, a fluorine-free polyimide resin is dried to a thickness of 0.3 m. After coating and drying, the lower cladding layer (8 m) and core layer (6.5 ju) made of polyimide resin containing fluorine m) formed. Next, a silicon-containing resist is applied on the core layer so as to have a thickness of 0.5, dried, exposed and developed through a core pattern, and reactive ion etching is performed using the resist pattern as a mask. A layer was formed. After stripping the resist, an upper cladding layer (15 zm) was formed to create a polyimide optical waveguide. After that, the cladding layers on both sides of the core layer are deleted leaving about 5 times (about 32.5〃m) the core layer width (6.5 jam), and then cut into chips by dicing, and the optical waveguide is cut. Were evaluated for optical crosstalk. Comparative Example 2

As in Example 2, a polyimide optical waveguide was formed on a silicon wafer by a spin coating method and a reactive ion etching method, and thereafter, a chip was formed by dicing without removing the cladding layers on both sides of the core layer. The cutout was used to evaluate the optical crosstalk of the optical waveguide.

As a result, the optical cross-section of the module of Example 2 of the present invention from which the cladding layer was removed was clearly improved as compared with the module of Comparative Example 2. Industrial applicability

According to the first embodiment of the present invention, since the substrate is provided with the optical crosstalk reducing means, the optical waveguide type optical transceiver module manufactured using this substrate has a remarkable optical crosstalk. , And a decrease in reception sensitivity can be significantly suppressed. Further, since the optical crosstalk reducing means is provided on the substrate, the manufacture thereof is easier than the conventional method of providing the optical element on the substrate with the optical crosstalk reducing means.

Further, according to the second embodiment of the present invention, the optical waveguide type optical transceiver module of the present invention provided with the optical crosstalk reducing means has a significantly reduced optical crosstalk. However, it is possible to remarkably suppress a decrease in reception sensitivity ₍

Two

Claims

The scope of the claims

1. An optical waveguide type optical transceiver module comprising a substrate and an optical element formed on the surface thereof, wherein the substrate is provided with an optical crosstalk reducing means.

2. The optical waveguide type optical transceiver module according to claim 1, wherein the optical crosstalk reduction means includes means for absorbing and blocking or blocking the leaked light or changing the optical path of the leaked light.

3. The light guide according to claim 1, wherein the optical crosstalk reducing means scatters light leakage by roughening the back surface and / or the surface of the substrate, thereby preventing the light from entering the light receiving element. Waveguide type optical transceiver module.

4. The optical waveguide type optical transceiver module according to claim 3, wherein the degree of surface roughening is JIS Rmax 6 to l2 m.

5. The optical waveguide type optical transmission / reception module according to claim 1, wherein the optical crosstalk reducing means is a substrate made of a metal, a ceramic, a resin, or a combination of two or more of them, which is opaque at a used wavelength.

6. An optical waveguide type optical transceiver module using a multiplexing / demultiplexing filter, wherein the optical crosstalk is within 5 dB. Ο

7. In an optical waveguide type optical transceiver module including a lower cladding layer, a core layer, an upper cladding layer in which the core layer is embedded, a light receiving element, and a light emitting element, at least the core layer near the light emitting element An optical waveguide type optical transceiver module, characterized in that the width of the cladding layer adjacent to the optical waveguide is 3 to 5 times the width of the core layer.

8. The optical waveguide type optical transmission / reception module according to claim 7, wherein the surface of the cladding layer configured to be 3 to 5 times the width of the core layer is coated with a light-impermeable material.

9. The optical waveguide type optical transceiver according to claim 8, wherein the light-impermeable material is metal or resin. Jules.

10. A substrate for producing an optical waveguide type optical transmission / reception module, which is provided with optical crosstalk reduction means.

11. The substrate for producing an optical waveguide type optical transceiver module according to claim 10, wherein the optical crosstalk reducing means includes means for absorbing and / or blocking light leakage or changing an optical path of light leakage.

12. The light guide according to claim 10, wherein the optical crosstalk reducing means scatters light leakage by roughening the back surface and / or the surface of the substrate, thereby preventing the light from entering the light receiving element. Substrate for making waveguide type optical transceiver module.

13. The substrate for producing an optical waveguide type optical transceiver module according to claim 12, wherein the degree of surface roughening is JISRmax6 to l2〃m.

14. The substrate for producing an optical waveguide-type optical transceiver module according to claim 10, wherein the optical crosstalk reducing means is an opaque metal, ceramic, resin, or a combination of two or more of these at the operating wavelength.

Four