JP2005331582A - Optical waveguide type wdm multiplexer/demultiplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive optical waveguide type WDM multiplexer/demultiplexer having a simple structure and a characteristic stability. <P>SOLUTION: In the optical waveguide type WDM multiplexer/demultiplexer 1, a grating part is formed at a branch part which demultiplexes or multiplexes light propagated in a core furnished in a midway of an optical waveguide core. It is preferable that the optical waveguide type WDM multiplexer/demultiplexer 1 is composed of an organic polymer material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a low cost optical waveguide type WDM multiplexer / demultiplexer having a simple structure for multiplexing and demultiplexing light of a plurality of wavelengths.

  In recent years, introduction of FTTH (Fiber To The Home) has started, and information communication networks represented by the Internet have rapidly spread to homes beyond the range of offices.

  In such a situation, the form of an access network that can provide services to each user is diversified. In particular, an ATM-PON (Asynchronous Transfer Modebased) which is an economical high-speed broadband access system using an optical fiber as a transmission path. Early introduction of the Passive Optical Network) system is being studied.

  ATM-PON is a wavelength division multiplexing optical communication system for subscribers using, for example, light in the wavelength band of 1.31 μm (voice) and light in the band of 1.49 μm (computer data) and 1.55 μm (image) in the downstream. The system is standardized by the ITU (International Telecommunication Union).

  Therefore, in order to separate and synthesize the wavelengths of 1.31 μm, 1.49 μm, and 1.55 μm, a WDM (Wavelength Division Multiplexing) multiplexer / demultiplexer is required. An ONU (Optical Network Unit) device including this multiplexer / demultiplexer, LD (Laser Diode), and PD (Photo Diode) is a basic unit for spreading an optical fiber network to each home.

  Conventionally, an optical waveguide type WDM multiplexer / demultiplexer is generally made of quartz glass, and a combination of a quartz type waveguide and a filter is used (for example, see Patent Document 1). In addition, a method of configuring a filter using a micro optical system is also provided.

  On the other hand, an optical waveguide type WDM multiplexer / demultiplexer that uses an organic polymer material that is superior in processing performance and is cheaper than quartz glass is also being used in order to reduce the price (for example, see Patent Document 2).

JP 2000-241645 A JP 2002-243960 A

  By the way, the conventional techniques as described above have the following problems to be solved.

  That is, the optical waveguide type WDM multiplexer / demultiplexer as shown in Patent Document 1 has a problem that a groove is required in the middle of the optical waveguide to insert a filter, and the process becomes complicated and expensive. there were. Moreover, there are many interfaces due to the grooving, and there is a problem that the insertion loss increases and the characteristics become unstable.

  In addition, a filter constructed using a micro-optical system requires high-precision technology for assembling the optical system, is difficult to stabilize because of its characteristics, and many parts constituting the optical system are expensive. There was a problem.

  On the other hand, an optical waveguide type WDM multiplexer / demultiplexer using an organic polymer material such as fluorinated polyimide and a dielectric multilayer filter or a micro optical system as shown in Patent Document 2 is composed of quartz glass in terms of price. Although it is cheaper than the optical waveguide type WDM multiplexer / demultiplexer, the above-mentioned problems still cannot be solved.

  When the Internet is widespread and an optical waveguide WDM multiplexer / demultiplexer is used in the home, a small and low-priced device is essential. Accordingly, the present invention has been made paying attention to the above points, and an object thereof is to provide an optical waveguide type WDM multiplexer / demultiplexer having a simple structure, good characteristic stability, and low cost. .

  In order to solve the above-described problems, the present invention has the following configuration.

  That is, the optical waveguide type WDM multiplexer / demultiplexer according to the first aspect of the present invention receives light of a plurality of wavelengths from one input port, and internally demultiplexes the light into a single light from a plurality of output ports. In an optical waveguide type WDM multiplexer / demultiplexer that emits light having a plurality of wavelengths from a plurality of input ports, multiplexes the light beams from the input ports, and emits the light from one output port. A grating portion is formed at a branching portion that demultiplexes or multiplexes light propagating in the core provided in FIG.

  As a second aspect, in the first aspect, the optical waveguide WDM multiplexer / demultiplexer is made of an organic polymer material.

  Further, as a third aspect, in the second aspect, the organic polymer material is a kind selected from fluorinated polyimide, polysilane, polymethyl methacrylate, and polycarbonate.

  Furthermore, as a fourth aspect, in the second or third aspect, the grating portion is formed by a hot embossing method.

  According to a fifth aspect, in the second or third aspect, the grating portion is formed by a laser irradiation method.

  Since the grating part is formed at the branch part that splits or multiplexes the light propagating in the core provided in the middle of the core of the optical waveguide, it does not go through complicated steps such as insertion of filters and assembly of micro optical system An optical waveguide WDM multiplexer / demultiplexer that has a simple structure and can be miniaturized can be realized, and the cost can be reduced by using an organic polymer material. Therefore, the optical waveguide WDM has stable characteristics and is inexpensive. A multiplexer / demultiplexer can be provided.

  Hereinafter, embodiments of the present invention will be described using specific examples.

  FIG. 1 is a diagram schematically showing a first embodiment of an optical waveguide WDM multiplexer / demultiplexer according to the present invention. In the figure, only the core part is shown for the sake of explanation, and the cladding part is omitted. In FIG. 1, an optical waveguide WDM multiplexer / demultiplexer 1 according to the present invention is a Y-branch multiplexer / demultiplexer, and has one or a plurality of input ports 2 and output ports 3 (3a, 3b, 3c). A grating part is formed in the branch part 4 (4a, 4b, 4c) of each of these input / output ports in the waveguide 5 (5a, 5b, 5c, 5d, 5e, 5f).

  The optical waveguide WDM multiplexer / demultiplexer 1 of the present invention is preferably made of an organic polymer material such as fluorinated polyimide, polysilane, polymethyl methacrylate, or polycarbonate. Since such an organic polymer material is inexpensive and easy to process, it is possible to provide a comprehensively low-priced product as compared with a quartz glass-based optical waveguide type WDM multiplexer / demultiplexer.

  When the grating portion is formed in the branch portion 4 of the optical waveguide WDM multiplexer / demultiplexer 1 using the organic polymer material as described above, a hot embossing method or a laser irradiation method using ultraviolet light may be used. In any case, fine processing can be performed on the organic polymer material, and stabilization of the WDM characteristics can be realized.

  FIG. 2 is a diagram schematically showing a second embodiment of the optical waveguide type WDM multiplexer / demultiplexer according to the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals. Similarly to FIG. 1, only the core part is shown, and the clad part is omitted. In FIG. 2, an optical waveguide type WDM multiplexer / demultiplexer 1 according to the present invention is an L-branch multiplexer / demultiplexer, and similarly to FIG. 1, one or a plurality of input ports 2 and output ports 3 (3a, 3b, 3c). ) And gratings at the branch portions 4 (4a, 4b, 4c, 4d) of these input / output ports in the waveguide 5 (5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h) The part is formed.

  Here, regarding the operation of the optical waveguide type WDM multiplexer / demultiplexer 1 of the present invention, for example, light of three wavelengths is multiplexed and incident on one input port 2, and these lights are demultiplexed to output ports 3a, The case where it radiate | emits to 3b and 3c is demonstrated.

  First, in the first embodiment, light of three wavelengths λ 1, λ 2, and λ 3 is multiplexed and incident from one input port 2. These lights propagate through the waveguide 5a and reach the first grating portion 4a. The first grating section 4a has a function of reflecting light having a wavelength of λ1 and allowing light having other wavelengths of λ2 and λ3 to pass therethrough. Accordingly, light having a wavelength of λ1 is reflected by the first grating portion 4a, propagates through the waveguide 5b, and is emitted from the output port 3a.

  Then, light having wavelengths λ2 and λ3 further propagates through the waveguide 5c and reaches the second grating portion 4b. The second grating portion 4b has a function of reflecting light having a wavelength of λ2 and allowing light having a wavelength of λ3 to pass therethrough. Accordingly, light having a wavelength of λ2 is reflected by the second grating portion 4b, propagates through the waveguide 5d, and is emitted from the output port 3b.

  Next, light having a wavelength of λ3 that has passed through the second grating portion 4b propagates through the waveguide 5e and reaches the third grating portion 4c. Since the third grating portion 4c has a function of reflecting light having a wavelength of λ3, the light having a wavelength of λ3 is reflected by the third grating portion 4c and propagates through the waveguide 5f to be output port 3c. More light is emitted. Here, the waveguide 5g is not directly involved in the propagation of light in the present embodiment, but is necessary when a larger number of grating portions are formed.

  In the second embodiment, light of three wavelengths λ 1, λ 2, and λ 3 is also multiplexed and incident from one input port 2. These lights propagate through the waveguide 5a and reach the first grating portion 4a. The first grating section 4a passes any of the three wavelengths λ1, λ2, and λ3, and guides it to the waveguide 5b by changing the propagation direction by, for example, 90 degrees in the present embodiment. The three wavelengths λ1, λ2, and λ3 that have propagated through the waveguide 5b reach the second grating portion 4b.

  The second grating section 4b has a function of changing the propagation direction of the light having the wavelength of λ1 by 90 degrees, propagating the light through the waveguide 5c and outputting it from the output port 3a, and passing the wavelengths of λ2 and λ3. The wavelengths λ2 and λ3 propagate through the waveguide 5d and reach the third grating portion 4c.

  The third grating portion 4c has a function of changing the propagation direction of the light having the wavelength of λ2 by 90 degrees, propagating the light through the waveguide 5e and outputting it from the output port 3b, and passing the wavelength of λ3. The wavelength λ3 propagates through the waveguide 5f and reaches the fourth grating portion 4d.

The fourth grating section 4d has a function of changing the propagation direction of light having a wavelength of λ3 by 90 degrees to propagate the waveguide 5g and output it from the output port 3c. Here, the waveguide 5h is not directly involved in the propagation of light in the present embodiment, but is necessary when a larger number of grating portions are formed.
A plurality of optical signals multiplexed in this way are respectively demultiplexed into individual light beams in the optical waveguide WDM multiplexer / demultiplexer. In the present invention, a dielectric multilayer filter is provided in the waveguide. Since it is not necessary to insert the optical waveguide type WDM multiplexer / demultiplexer in each home, the structure is simple and the size can be reduced.

  By the way, as described above, demultiplexing has been described in the present embodiment. However, in the case of multiplexing, the light propagation path may be reversed. That is, in the first embodiment, when light having a wavelength of λ3 is first incident from the port 3c, this light propagates through the waveguide 5f, is reflected by the third grating portion 4c, and propagates through the waveguide 5e. I will do it. Therefore, when the light having the wavelength of λ3 reaches the second grating portion 4b, the light having the wavelength of λ3 passes through the second grating portion 4b, so that the light having the wavelength of λ3 propagates through the waveguide 5c. go.

  On the other hand, light having a wavelength of λ2 incident from the port 3b propagates through the waveguide 5d, reaches the second grating portion 4b, is reflected, and propagates through the waveguide 5c. At this time, light having a wavelength of λ3 and light having a wavelength of λ2 are multiplexed in the waveguide 5c, multiplexed, and propagated.

  Next, light having a wavelength of λ1 incident from the port 3a propagates through the waveguide 5b, is reflected by the first grating portion 4a, and propagates through the waveguide 5a. The multiplexed light having the wavelength of λ3 and light having the wavelength of λ2 propagated through the waveguide 5c passes through the first grating section 4a and propagates through the waveguide 5a. As a result, the light of wavelengths λ3, λ2, and λ1 is multiplexed and propagated in the waveguide 5a, and the multiplexed light of the three wavelengths is emitted from the port 2. The operation of this multiplexing is the same in the second embodiment.

  In the above-described embodiment, the branching portion refers to a portion having a function of substantially demultiplexing or multiplexing light, but in the vicinity of the branching portion if necessary for operation and effect to realize the function. In other words, it is not necessary to interpret only the branching points.

  In order to create the Y-branch type multiplexer / demultiplexer in the first embodiment, polysilane, which is an organic polymer material, is applied to the target waveguide shape on the Si substrate, and the film thickness is controlled by spin coating. The lower clad was formed while heating. Next, polysilane was further applied onto the heat-cured lower clad while controlling the film thickness by spin coating. The mask layer was used to irradiate ultraviolet light to give a refractive index difference to form a core layer. Thereafter, the grating portion was formed by irradiating the branched portion with ultraviolet laser light. Finally, polysilane was applied, the film thickness was controlled by spin coating, and heat curing was performed to form an upper clad.

  The optical waveguide type WDM multiplexer / demultiplexer of the present invention thus produced has a good grating characteristic with an optical insertion loss of 5.2 dB or less, a polarization dependent loss of 0.1 dB or less, and a reflection loss of 35 dB or more. Indicated. Further, stable characteristics were exhibited even in the test temperature range of -10 to 60 ° C.

It is a figure showing 1st embodiment of this invention. It is a figure showing 2nd embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical waveguide type WDM multiplexer / demultiplexer 2 ... Input port 3 ... Output port 4 ... Grating part 5 ... Waveguide

Claims (5)

  Multiple wavelengths of light are incident from a single input port and internally demultiplexed into a single light and emitted from multiple output ports, or multiple wavelengths of light are incident from multiple input ports, respectively. In the optical waveguide type WDM multiplexer / demultiplexer that multiplexes and emits from one output port, a grating portion is added to a branching portion that demultiplexes or multiplexes light propagating in the core provided in the middle of the core of the optical waveguide An optical waveguide type WDM multiplexer / demultiplexer characterized by comprising:   2. The optical waveguide WDM multiplexer / demultiplexer according to claim 1, wherein the optical waveguide WDM multiplexer / demultiplexer is made of an organic polymer material.   3. The optical waveguide WDM multiplexer / demultiplexer according to claim 2, wherein the organic polymer material is one selected from fluorinated polyimide, polysilane, polymethyl methacrylate, and polycarbonate.   4. The optical waveguide WDM multiplexer / demultiplexer according to claim 2, wherein the grating portion is formed by a hot embossing method. 4. The optical waveguide WDM multiplexer / demultiplexer according to claim 2, wherein the grating portion is formed by a laser irradiation method.

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