JP2011002793A - Optical waveguide, method for fabricating the optical waveguide, and nonlinear optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce nonuniformity of a solid medium resulting from a lengthened size, in a method for fabricating an optical waveguide which has a core constructed with the solid medium.SOLUTION: A claddingd material 402 is applied to an original plate 401 (Fig.4(a)). A first cladding sheet 403 is applied thereto with a lamination method (Fig.4(b)). After lamination, the excessive solvent etc. are removed with heating and the first cladding sheet 403 is peeled off from the original plate 401, and a soft stamper 404 which has a recessed section 404A is obtained (Fig.4(c)). A second cladding sheet 405 is stuck to the soft stamper 404A with a lamination method (Fig.4(d)), and a cladding section 406A, having a hollow section 406B is obtained (Fig.4(e)). Finally, an UV resin is sealed in the hollow section 406B by using a capillary phenomenon; and when it is successively subjected to ultraviolet irradiation, the core 406B' is solidified; and the optical waveguide 400 having the cladding section 406A and the core 406B' is obtained (Fig.4(f)).

Description

  The present invention relates to an optical waveguide, a method for manufacturing the optical waveguide, and a nonlinear optical device. In particular, the present invention relates to a non-linear optical device useful as an optical switch, an optical memory, an optical signal arithmetic processing device or the like used for optical data processing, information processing, an optical communication system, and the like.

  As a nonlinear optical device such as an optical switch using a nonlinear optical effect, for example, various optical Kerr shutter type optical switches, Mach-Cender type optical switches, directional coupler type optical switches, and the like are known.

  As schematically shown in FIG. 1, the optical Kerr shutter type optical switch has a polarizer and an analyzer arranged in a crossed Nicol arrangement in which polarization axes are orthogonal to each other, and a nonlinear optical medium (Kerr medium) is detected as a polarizer. It is interposed between photons. Input light (probe light) is gated by a pulse of gate light, and becomes output light corresponding to the time waveform of the gate pulse. In this configuration, only while the gate light is incident, the linearly polarized light of the probe light that has passed through the polarizer is changed to elliptically polarized light by the change in the refractive index generated in the Kerr medium. Therefore, a part of the probe light can pass through the orthogonal analyzer, and the probe light is optically switched by the pulse of the gate light.

  The transmittance of the probe light passing through the analyzer becomes maximum when the angle formed by the linearly polarized light of the gate light Pg and the probe light Pi is π / 4. The transmittance T of the probe light Pi at this time is given by Expression (1).

However, n _2B is the nonlinear refractive index called Kerr constant, L is the length of the Kerr medium, Ig (= 4 Pg / πD ² ) is the power density of the gate light Pg, and D is the beam spot size. In the waveguide medium, D can be regarded as the core diameter.

  An optical Kerr shutter type optical switch using high-efficiency glass or organic material in place of the conventional representative example of the silica fiber has been reported. For example, 4- (N, N-diethylamino) -β-nitrostyrene (hereinafter referred to as “4- (N, N-diethylamino) -β-nitrostyrene”). In an optical car shutter experiment using “DEANST” as a car medium, in addition to a relatively high-speed response of picoseconds, a relatively high-efficiency optical switching operation is realized (see Patent Document 1).

  However, the Kerr medium mainly shown in Patent Document 1 has a problem that it is difficult to handle because its form is a solution. In addition, in solution materials, the molecular Kerr effect, which is slightly inferior to the ultra-high-speed nonlinear polarization effect, is added as a factor causing the optical Kerr effect, so molecular design is required to achieve a high-speed response in the complete femtosecond class. There is also the problem of becoming. Therefore, it is necessary to suppress the molecular orientation effect by using a solution in which organic molecules having a very long molecular length are dissolved as a Kerr medium, and the selection range of materials has been narrowed (see Patent Document 2).

  One effective means of suppressing molecular orientation effects is the application of solid materials. However, since the efficiency of the solid material itself is not sufficient, for example, it is unavoidable to make it long in order to be driven by a small laser, but conventionally, it has been difficult to produce a long solid optical medium. It stopped at the order of 10 centimeters.

  FIG. 2 is a diagram showing a conventional representative example of a Mach-Cender type optical switch. This utilizes the electro-optic effect of lithium niobate, and the core is produced by thermally diffusing titanium on a lithium niobate substrate. Lithium niobate is an optical crystal having an electro-optic effect, and its refractive index can be changed by applying an electric field. For this reason, when the configuration shown in FIG. 2 is adopted, the propagation coefficient of light propagating in the core changes as the refractive index changes due to the electric field, and a phase difference occurs when the two branched lights are combined. . Since the intensity of the light output according to the phase difference changes due to interference, it acts as a switch by changing the potential applied to the electrode.

  However, a switch using such an electro-optic effect has a drawback that it is not suitable for use as a high-speed switch due to limitations due to electric circuit-like stray capacitance. Therefore, there is a demand for a Mach-Cender optical switch that does not have such restrictions. However, as with the optical Kerr shutter optical switch shown in FIG. 1, there is a problem that there is no highly efficient material.

Therefore, an optical medium with a large nonlinear optical effect and a low light intensity required for operation was eagerly awaited, and as a result of active research and development, an optical fiber made of glass containing semiconductor fine particles and a highly efficient organic material were developed. Although optical fibers encapsulating crystals have been developed, these also have a number of problems with respect to light transmittance and optical waveguide structure. In the case of an optical fiber made of glass added with semiconductor fine particles, the nonlinear optical effect is 10 ⁴ to 10 ⁵ times larger than that of SiO ₂ , but the optical absorptance at the operating wavelength is large. The length must be extremely short, and after all, it is difficult to obtain a large nonlinear optical effect. In the case of an optical fiber encapsulating an organic crystal, the nonlinear optical effect per unit length is 10 ² or more larger than that of quartz glass, and the light absorption rate at the operating wavelength is small. Due to the non-uniformity of the light, it is inferior to the light transmittance and the linear polarization maintenance of the incident light. In addition, it is difficult to finely adjust the refractive index difference between the core portion and the clad portion of the optical fiber uniformly over the entire range. For this reason, an appropriate optical waveguide structure is formed to increase the light intensity. Is difficult.

  FIG. 3 is a diagram showing a conventional example of a directional coupler type optical switch. In this optical switch, when two optical waveguides are sufficiently close to each other, a light wave mode incident on one optical waveguide (nonlinear optical waveguide) is coupled to the other optical waveguide (an optical waveguide made of a normal medium). A phenomenon is used in which the transmission light energy moves between the modes, and as a result, the light energy from the emission end is turned on and off. In the region where the power of the input light P0 is small, the power of the output P1 is overwhelmingly larger than the power of the output P2, but as the power of the input light P0 is gradually increased, the transmission light energy between the two modes is reduced. As a result, a switching operation occurs in which the power of the output P1 decreases and, instead, the power of the output P2 gradually increases.

  However, the directional coupler type optical switch has the same problems as the optical Kerr shutter type optical switch and the Mach-Cender type optical switch described above, and is not practical because the material efficiency is low. In addition, although the problem of inefficiency of the material itself can be reduced if the length is increased, there is a limit to the lengthening and the uniformity of the medium.

JP 05-005909 A Japanese Patent Laid-Open No. 07-234424 JP 2008-058531 A

  The present invention has been made in view of such problems, and a first object of the present invention is to provide a non-uniform solid medium when the optical waveguide having a core portion made of a solid medium is elongated. It is to reduce the property.

  A second object of the present invention is to reduce the non-uniformity of the solid medium when the length is increased in the method of manufacturing an optical waveguide having a core portion made of a solid medium.

  A third object of the present invention is to provide a nonlinear optical device including an optical waveguide in which non-uniformity of a solid medium is reduced when the length is increased.

  In order to achieve such an object, a first aspect of the present invention is an optical waveguide having a resinous cladding portion and a core portion made of a solid medium, and the solid medium is ultraviolet curable. It is a resin.

  According to a second aspect of the present invention, in the first aspect, the ultraviolet curable resin is mixed with an organic material exhibiting a nonlinear optical effect.

  According to a third aspect of the present invention, there is provided an optical waveguide having a resinous cladding part and first and second core parts made of a solid medium, wherein the solid medium is an ultraviolet curable resin. And an organic material exhibiting a nonlinear optical effect is mixed only in the solid medium of the first core portion.

  According to a fourth aspect of the present invention, there is provided a method for producing an optical waveguide having a resinous clad part and a core part made of a solid medium, the step of providing a resinous clad part having a hollow part. And introducing a UV curable resin into the hollow part by capillary action, and solidifying the UV curable resin introduced into the hollow part by ultraviolet irradiation to form a core part. And

  According to a fifth aspect of the present invention, in the fourth aspect, an organic material exhibiting a nonlinear optical effect is mixed into the ultraviolet curable resin.

  According to a sixth aspect of the present invention, in the fourth or fifth aspect, the step of providing the resinous clad portion having the hollow portion includes a step of applying a resin on an original plate, The first resin sheet is applied to the surface by a laminating method to produce a soft stamper having a recess, and the second resin sheet is bonded to the surface of the soft stamper where the recess is formed, so that the hollow portion is formed. Providing the clad part.

  In addition, according to the seventh aspect of the present invention, the gate light is incident on the optical waveguide together with the incident light that has passed through the polarizer, and the incident light that has passed through the optical waveguide is extracted as outgoing light through the analyzer. In the optical device, the optical waveguide is the optical waveguide according to the second aspect.

  The eighth aspect of the present invention includes a nonlinear material that demultiplexes incident laser light and passes one of the demultiplexed light waves to the first core portion including the nonlinear material to give a phase shift. In the nonlinear optical device that obtains output light in which the input light is modulated by combining with the other light wave that has not been subjected to the phase shift that has been demultiplexed to the second core part that is not present, The second core portion is the first and second core portions of the optical waveguide of the third aspect.

  Further, according to the ninth aspect of the present invention, only the first core part of the first and second core parts adjacent to each other includes a nonlinear material, and the light wave mode incident on one core part is the other. In the nonlinear optical device that couples with the light wave mode incident on the core part and turns on / off the light energy from the output end by the movement of the transmitted light energy occurring between the two modes, the first core part and the second core The parts are first and second core parts of the optical waveguide of the third aspect.

  According to the optical waveguide of the present invention, since the core portion of the optical waveguide is made of the ultraviolet curable resin, the non-uniformity of the solid medium when the length is increased can be reduced. In addition, according to the method for producing an optical waveguide of the present invention, by introducing an ultraviolet curable resin into the hollow portion of the cladding portion by capillary action, the non-uniformity of the solid medium when lengthened can be reduced. it can. Further, according to the nonlinear optical device of the present invention, the solid medium of the core part is an ultraviolet curable resin, and at least part of the core part is used by using an optical waveguide mixed with a nonlinear material. A nonlinear optical device including an optical waveguide with reduced non-uniformity of a solid medium can be provided.

It is a figure which shows the prior art example of an optical Kerr shutter type | mold optical switch. It is a figure which shows the prior art example of a Mach-Cender type | mold optical switch. It is a figure which shows the prior art example of a directional coupler type | mold optical switch. (A)-(f) is a figure which shows the preparation methods of the optical waveguide concerning embodiment of this invention. It is a figure which shows the linear optical waveguide produced with the production method demonstrated with reference to FIG. It is a figure which shows the optical Kerr shutter type | mold optical switch by Example 1-1. It is a figure which shows the relationship between the probe light transmission rate of the optical Kerr shutter type | mold optical switch by Example 1-1, and gate optical power. It is a figure which shows the optical waveguide which concerns on Example 1-2. It is a figure for demonstrating the two-layer optical waveguide for Mach-Cender type | mold optical switches by Example 2-1. (A) is a bottom view of the waveguide 1 of the two-layer optical waveguide according to Example 2-1, and (b) is a side view of the two-layer optical waveguide of Example 2-1. (A) is a top view of the waveguide 2 of the two-layer optical waveguide which concerns on Example 2-1, (b) is a side view of the two-layer optical waveguide of Example 2-1. It is a figure which shows the mode of the propagation of the beam in the two-layer optical waveguide which concerns on Example 2-1 in three dimensions. It is a figure which shows the result of the optical switching experiment of the Mach-Cender type | mold optical switch by Example 2-1. (A) is the bottom view of the waveguide 1 of the two-layer optical waveguide which concerns on Example 2-2, (b) is a side view of the two-layer optical waveguide of Example 2-2. (A) is a top view of the waveguide 2 of the two-layer optical waveguide which concerns on Example 2-2, (b) is a side view of the two-layer optical waveguide of Example 2-2. (A) is a bottom view of the waveguide 1 of the two-layer optical waveguide according to Example 3-1, and (b) is a side view of the two-layer optical waveguide of Example 3-1. (A) is a top view of the waveguide 2 of the two-layer optical waveguide which concerns on Example 3-1, (b) is a side view of the two-layer optical waveguide of Example 3-1. It is a figure which shows the mode of the propagation of the beam in the two-layer optical waveguide which concerns on Example 3-1 in three dimensions. It is a figure which shows the relationship between the output optical power of the directional coupler type | mold optical switch by Example 3-1, and input optical power. (A) is a bottom view of the waveguide 1 of the two-layer optical waveguide according to Example 3-2, and (b) is a side view of the two-layer optical waveguide of Example 3-2. (A) is a top view of the waveguide 2 of the two-layer optical waveguide which concerns on Example 3-2, (b) is a side view of the two-layer optical waveguide of Example 3-2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
4A to 4F show a method of manufacturing an optical waveguide according to an embodiment of the present invention, and FIG. 4F shows the final optical waveguide structure. The optical waveguide 400 has a structure in which a core portion 406B ′ made of an ultraviolet curable resin (hereinafter also referred to as “UV resin”) is embedded in a resinous cladding portion 406A. The UV resin constituting the core portion 406B ′ may be mixed with an organic material that exhibits a nonlinear optical effect (hereinafter also referred to as “nonlinear material”) in order to have a nonlinear optical effect.

  The manufacturing method according to the embodiment of the present invention is as follows. First, the clad material 402 is applied on the original plate 401 (FIG. 4A). A first clad sheet 403 (corresponding to “first resin sheet”) is applied thereon by a laminating method (FIG. 4B). The laminating method generally refers to a method for producing a waveguide in which waveguides are bonded together by applying pressure with a roller. The first clad sheet 403 is formed, for example, by previously applying the same clad material 403B as applied to the original plate 401 on a PET film (polymer film made of polyethylene terephthalate resin) 403A by a blade coating method or the like. The clad sheet 403 may be a transparent sheet and is not limited to PET. After the lamination, heating is performed to remove excess solvent and the first clad sheet 403 is peeled off from the original 401, so that a soft stamper 404 having a concave portion 404A corresponding to the core portion of the optical waveguide is produced. (FIG. 4 (c)). In this specification, the “soft stamper” is not a hard (literally hard) stamper such as a silicon original plate but a soft, that is, soft stamper. The soft stamper method is not easily affected by the pressure distribution when the waveguide pattern is transferred, and it is easy to increase the area of the waveguide. The soft stamper method has a feature that the process is simple. Details of the soft stamper method are disclosed in Patent Document 3.

  When the second clad sheet 405 (corresponding to the “second resin sheet”) is bonded to the soft stamper 404A by the laminating method (FIG. 4D), the clad part 406A having the hollow part 406B is completed. (FIG. 4E). Finally, if one end of the cladding portion 406A having the hollow portion 406B is immersed in a solution filled with the UV resin, the UV resin is automatically enclosed in the hollow portion 406B by capillary action. If ultraviolet irradiation is performed in this state, the core portion 406B ′ is solidified, and the optical waveguide 400 having the clad portion 406A and the core portion 406B ′ is obtained (FIG. 4F).

  Regarding the end face processing of the optical waveguide 400, it is possible to polish the end face by a normal polishing process. The medium of the core part manufactured by this method has optical uniformity, and the optical characteristics are remarkably improved as compared with a conventional optical waveguide using an organic crystal. By mixing an organic material exhibiting a nonlinear optical effect into the UV resin introduced into the core part, the core part can have a nonlinear optical effect.

  The UV resin may be basically any UV curable resin, such as a commercially available UV curable resin, for example, an epoxy resin from NTT Advanced Technology, a visible light curable resin from Three Bond, Hitachi Chemical. For example, UV curable resin manufactured by the company, UV resin manufactured by DuPont or Mitsubishi Rayon can be used. Any of these can be used to uniformly enclose the material in the hollow portion 406B of the cladding portion 406A by utilizing capillary action. An increase in the degree of freedom in material selection is also a great advantage of the manufacturing method according to the present invention.

  As the organic material having a nonlinear optical effect, in addition to the above-mentioned DEANST, ionic crystal material 4′-dimethylamino-N-methyl-4-stilbazolium methosulfonate salt (hereinafter referred to as “DMSM”), tricycle. The benzylidene aniline derivative terephthal-bis [(p-diethylamino) aniline] (hereinafter referred to as “SBAC”) can be used. Furthermore, molecular crystal materials such as 4-nitroaniline (p-NA), 4- (N, N-diethylamino) nitrobenzene (p-DEANB), 2-methyl-4-nitroaniline (MNA), 4-nitro Nitroaniline and its derivatives such as phenylprolinol (NPP), 4-cyclooctylaminonitrobenzene (COANB), N-cyanomethyl-N-methyl-4-nitroaniline (CMMNA), 4-cyclooctylaminonitropyridine (COANP) Nitropyridine derivatives such as 4-adamantanaminonitropyridine (AANP), 2- (N-propinol) -5-nitropyridine (PNP), 4-methoxy-4′-nitrostilbene (MNS), 4-bromo-4 '-Nitrostilbene (BNS), 4- (N, N-dimethyl) Mino) -4′-nitrostilbene (DMANS0, 4- (N, N-diethylamino) -4′-nitrostilbene (DEANS), 4- (N, N-dipropylamino) -4′-nitrostilbene (DPANS) Nitrostilbene derivatives such as 3-methyl-4-methoxy-4′-nitrostilbene (MMNS), 4- (N, N-dimethylamino) -4′-nitroazobenzene (DMANAB), 4- (N, N— Paraaminonitroazobenze conductors such as diethylamino) -4′-nitroazobenzene (DEANAB), benzoheterocyclic derivatives such as 5-nitroindole (5NIN) and chloronitrobenzooxadiazole (NBD-CI), or ionic crystals Metho of 4′-diethylamino-N-methyl-4-stilbazolium as material Dialkylaminostilbazolium derivatives such as sulfonate salt (DESM), iodine salt of 4′-diethylamino-N-methyl-4-stilbazolium (DESI), and pyridinium derivatives and azulenium derivatives represented by the structural formulas shown in Table 1 , Quinolium derivatives, or polydiacetylene derivatives that are π-electron conjugated polymer materials, polyarylene vinylenes typified by poly (paraphenylene vinylene) and poly (2,5-chenylene vinylene), and the like of these polymers It is possible to use an oligomer material having a basic unit as a constituent, and deuterated or fluorinated hydrogen constituting these molecules.

  If the optical waveguide 400 of this embodiment is used in an optical car shutter type optical switch, a Mach-Cender type optical switch, and a directional coupler type optical switch, the optical waveguide can be easily increased in area and length, and Since the medium of the core portion 406B ′ is excellent in uniformity, it is possible to simultaneously solve the two problems that have been the conventional problems, ie, lengthening and homogenization of the optical medium.

  As described above, the optical waveguide according to the present invention is manufactured through a manufacturing process using a capillary phenomenon in addition to the flexible stamper technology. A sufficient optical uniformity is obtained in the core portion constituted by In addition, according to the flexible stamper technology, it is possible to draw a wide variety of patterns in a large area. However, if the capillary phenomenon is used, the UV resin is uniformly enclosed in the hollow portion regardless of the shape of the optical waveguide. It also has the feature. Moreover, if a 45-degree mirror is installed, it is possible to make two layers or more layers and open up the possibility of a three-dimensional waveguide. “Long” is a commonly used term and has no strict definition. For example, in the case of a polymer waveguide, if it is 10 cm or more, it belongs to a long region.

  The nonlinear optical device using the optical waveguide of the present invention is used not only in high efficiency but also in good optical characteristics and the like, so that it is used in the fields of optical information processing and optical communication. In addition, since it is a planar optical waveguide, it can be widely developed such as connection with a PLC (Planar Lightwave Circuit) unlike the optical fiber type. Moreover, since the nonlinear optical device according to the present invention uses a nonlinear mechanism due to a pure electronic polarization effect, it can realize high-speed operation in femtoseconds in a wide wavelength range including a communication wavelength band. Furthermore, the optical waveguide of the present invention and the nonlinear optical apparatus using the same are not limited to optical devices that utilize the pure third-order nonlinear optical effect as described above, but other nonlinear optical effects such as a second-order nonlinear optical effect. It can also be diverted to the optical switch used.

  Examples are shown below.

  As Example 1, an optical Kerr shutter type optical switch is shown.

Example 1-1
FIG. 5 shows a linear optical waveguide manufactured by the manufacturing method described with reference to FIG. The waveguide length was 25 cm and the core size was 5 μm × 5 μm. The refractive index was adjusted so that the optical waveguide 500 was a single mode waveguide. As the material of the clad portion 500A, a UV curable epoxy resin manufactured by NTT Advanced Technology was used. As the material of the core portion 500B, a material in which DEANST is gradually mixed into a UV resin is used, and a material that has a concentration to become a single mode is used. As a result of examining the waveguide pattern in detail by varying the DEANST concentration, it was found that the characteristics were best when the DEANST concentration was 13.5% by weight. It was confirmed that the core portion 500B of the optical waveguide 500 has sufficient optical characteristics even after solidification by UV irradiation. The polarization maintaining rate of the linearly polarized wave was able to ensure 20 dB or more necessary for the optical Kerr shutter experiment.

  FIG. 6 shows an optical system of an optical Kerr shutter type optical switch. The gate light is a titanium sapphire laser light (150 fs, 1 kHz) having a wavelength of 0.78 μm that has passed through an optical parametric amplifier (OPA), and the probe light is a wavelength of 0.83 μm synchronized with the gate light pulse. A semiconductor laser beam having a width of 10 ns was used. The probe light is tilted by π / 4 with respect to the polarization direction of the linearly polarized light of the gate light by the λ / 2 wavelength plate, passes through the polarizer, mirror, and lens and reaches the optical waveguide. Squeezed.

In this optical system, since the gate light and the probe light are collinear (coaxial) by the mirror, the medium of the optical waveguide can be used as the Kerr medium. After passing through the optical waveguide, the probe light is further sent to the detector via a lens, a filter, and an analyzer. For the detector, a photomultiplier tube, a photodiode or the like was used. The gate light was blocked by the filter and did not reach the detector. In order to block the gate light, a spectroscope can be used instead of the filter. When the switching operation was investigated by adjusting the power of the gate light, the probe light passing rate T showed a behavior according to the equation (1), and the optical Kerr shutter operation was correctly shown as shown in FIG. confirmed. A phase change amount π was also realized, and from this result, the Kerr constant n _{2B of the} core material made of DEANST used in Example 1-1 was calculated to be 2 × 10 ⁻¹⁵ cm ² / W. There was no significant absorption in the wavelength band in the experiment of Example 1-1, and no influence of two-photon absorption was observed.

  For use in the communication wavelength band (1.3 μm, 1.5 μm), if the material is deuterated or fluorinated, switching with effectively reduced absorption becomes possible (even in the wavelength range of this embodiment). Deuteration and fluorination have the effect of lowering absorption). The repetition frequency is set to a sufficiently low repetition rate (= 1 kHz) in consideration of the mixing of the thermal effect in the first embodiment, but it is also possible to perform an experiment at a higher repetition frequency than this.

Example 1-2
In Example 1-1, the laser light that passed through the OPA of a large titanium sapphire laser was used as the light source. However, it is possible to drive a small laser as gate light by using a flexible stamper technology capable of increasing the area without being restricted by this. In Example 1-2, an optical waveguide having the pattern shown in FIG. 8 was produced. The core size was 5 μm × 5 μm, and the waveguide length was 1 m, taking advantage of the present invention. A commercially available semiconductor laser (wavelength 0.83 μm, output 100 mW, pulse width 10 ns, repetition frequency 1 kHz) is used for the gate light, and a semiconductor laser whose output is 1/100 times that of the gate light is also used for the probe light. It was. The nonlinear material and the UV resin were the same as those in Example 1-1.

  Also in Example 1-2, the optical Kerr shutter operation was confirmed, the phase change amount π / 4 was achieved, and the optical system was greatly downsized. In the optical car shutter type optical switch according to the present invention, it has been found that the same result can be obtained even if DMSM or SBAC is used in addition to DEANST. As shown in FIG. 8, the optical waveguide has not only a straight line but also a large curve. However, even when the beam passes therethrough, the waveguide characteristics are not deteriorated.

  In the photomultiplier tube or photodiode used in Example 1-2, its own response speed stops in nanoseconds. Therefore, the response speed of the optical Kerr shutter type optical switch was investigated by a general measurement method in which the probe light pulse is delayed with respect to the gate light pulse. As a result of the measurement, the switching speed was equal to or less than the pulse width of the incident gate light, and it was confirmed that optical switching occurred due to the high-speed electronic polarization effect that is a feature of the solid medium. In addition, speed reduction due to two-photon absorption and thermal effects, speed reduction due to group delay dispersion, and the like have been eliminated. Since the optical Kerr shutter switch employed in the present embodiment 1-2 has a switching speed of sub picoseconds or less, it can be arbitrarily selected from a modulation function that modulates signal light to 100 GHz or more and a signal light pulse train having a repetition frequency of 100 GHz or more. An optical car shutter type optical switch having a demultiplexing function for extracting signal pulses and converting them into a low repetition pulse train, a multiplexing function for multiplexing several low repetition optical pulse trains into an optical pulse train of 100 GHz or more, and the like.

  As a second embodiment, a Mach-Cender type optical switch is shown.

Example 2-1
Since the optical waveguide produced by the manufacturing method of the present invention can be easily laminated into two layers with an optical adhesive, the Mach-Zehnder type optical switch can be increased by using this two-layer optical waveguide. It becomes possible to carry out efficiently.

  FIG. 9 shows a manufacturing process of a two-layer optical waveguide for a Mach-Cender type optical switch. In accordance with the procedure shown in FIG. 4, two optical waveguides provided with a core pattern for a Mach-Cender optical switch are prepared. One of them is filled with only the same UV resin as in Example 1-1 (this) And the other is filled with a solution in which a nonlinear material such as DEANST is mixed with UV resin (this is referred to as an optical waveguide 2). Thereafter, a 45-degree mirror is provided on the two optical waveguides 1 and 2 at a position shown in FIG. 9 by a dicing technique or the like, and the optical waveguides are bonded together to complete. However, the position of the 45-degree mirror is different from the material encapsulated in each optical waveguide. Here, the 45-degree mirror is provided to enable the beam to move between layers by its total reflection function.

  FIGS. 10 (a) and 11 (a) show the pattern of the optical waveguide, the position of the 45-degree mirror, and the material to be sealed for the optical waveguides 1 and 2, respectively. FIGS. 10B and 11B are side views of the two-layer optical waveguide of Example 2-1. In the optical waveguide 2, two core portions are provided, but the nonlinear material is enclosed only in one. When a beam is input to the optical waveguide 1, it is guided as shown in FIG. In this configuration, a nonlinear refractive index change is caused only in the optical waveguide 2, and a phase difference that occurs when two branched lights are combined is obtained by the refractive index change caused thereby. The core part of the optical waveguide 1 plays the role of a mere transmission line.

  FIG. 12 shows the state of beam propagation in a three-dimensional manner. The beam introduced into the core portion of the optical waveguide 1 is guided in the optical waveguide 1 for a while and then split into two hands. One of the beams is transferred to the optical waveguide 2 by a 45-degree mirror and then guided into the nonlinear material. Waves return to the optical waveguide 1 again (beam A). The other is moved to the optical waveguide 2 by a 45-degree mirror, but after passing through only ordinary UV resin, returns to the optical waveguide 1 again (beam B), and the beams A and B are combined again. Of course, there is a phase difference between the beam A and the beam B, and this causes an optical switching operation.

  In Example 2-1, the optical waveguide length in the optical waveguide 2 causing the nonlinear optical effect was 10 cm, and the core size was 5 μm × 5 μm. The same clad material and core material as in Example 1-1 were used. Also in Example 2-1, as a result of examining the waveguide pattern in detail, it was found that the characteristics were the best when the concentration of DEANST was 13.5% by weight. It was also confirmed that even an optical waveguide having a core portion solidified by UV light irradiation has sufficient optical characteristics. The polarization maintenance rate of linearly polarized waves was able to ensure 20 dB or more necessary for the Mach-Cender switch experiment. The 45-degree mirror also has the necessary total reflection function, and the inter-layer movement of the beam was able to obtain a level sufficient for the experiment.

  In Example 2-1, a titanium sapphire laser beam (150 fs, 1 kHz) having a wavelength of 0.78 μm that passed through an OPA (optical parametric amplifier) was used, and a photomultiplier tube or a photodiode was used as a detector. FIG. 13 shows the result of the optical switching experiment. As shown in FIG. 13, the output light, which was initially 80%, was modulated by the third-order nonlinear optical effect, and as a result, changed to 20%. It was found that optical switching operation was realized. There was no significant absorption in the experimental wavelength band, and no effect of two-photon absorption was observed.

  For use in the communication wavelength band (1.3 μm, 1.5 μm), if the material is deuterated or fluorinated, switching with effectively reduced absorption becomes possible (as in Example 2-1). Even in the wavelength range, deuteration and fluorination have the effect of lowering absorption.) The repetition frequency is set to a sufficiently low repetition rate (= 1 kHz) in consideration of the mixing of the thermal effect in the present Example 2-1, but it is also possible to perform an experiment at a higher repetition frequency than this.

  In addition, if the technique of providing the 45 degree | times mirror shown in the present Example 2-1 is used, not only two layers but three or more layers are also possible. In other words, if a single-layer optical waveguide with a 45-degree mirror provided at the core of the optical waveguide is prepared, and these are bonded together with an optical adhesive, the beam can be developed into a three-dimensional optical waveguide that can move between layers one after another. Can be achieved. This multilayering is a particularly effective method for increasing the efficiency of the material itself by increasing the length because the length of the optical waveguide can be increased by the number of layers.

Example 2-2
The Mach-Cender type optical switch of the present invention can be driven by a small laser if the same idea as in Example 1-2 is advanced. In Example 2-2, the propagation of the beam in which the optical waveguide having the structure shown in FIGS. 14 and 15 is manufactured is the same as that in Example 2-1, but the flexible stamper technology is the same as in Example 1-2. Utilizing the features, the length has been increased. The port 1 of the optical waveguide 2 is filled with the same UV resin mixed with DEANST as in Example 1-1, and the port 1 is filled with only the UV resin. The effective waveguide length of the nonlinear optical waveguide made of DENAST or the like is set to 1 m taking advantage of the present invention. Only the UV resin was enclosed in the optical waveguide 1. As the light source, a commercially available semiconductor laser (wavelength 0.83 μm, output 100 mW, pulse width 10 ns, repetition frequency 1 kHz) was used. In the optical waveguide of Example 2-2, the polarization maintaining rate of linearly polarized waves was able to ensure 20 dB or more necessary for the Mach-Cender switch experiment.

  Also in Example 2-2, the operation of the Mach-Cender switch was confirmed, and it was found that the optical system was greatly downsized. It has been found that even with a Mach-Cender type optical switch according to the present invention, similar results can be obtained by using DMSM or SBAC in addition to DEANST. This Example 2-2 also made use of the characteristics of solidification, and was capable of high-speed response due to a pure electronic polarization effect in which speed-down due to two-photon absorption and thermal effects, speed-down due to group delay dispersion, and the like were eliminated. As shown in FIG. 15A, the optical waveguide has not only a straight line but also a large curve. However, even if the beam passes through the waveguide, the waveguide characteristics are not deteriorated.

  Example 3 shows a directional coupler type optical switch.

Example 3-1
Also in the directional coupler type optical switch, if a two-layer optical waveguide is used, highly efficient switching can be performed. In the directional coupler type optical switch, two optical waveguides provided with a core pattern for the directional coupler type optical switch are prepared according to the procedure shown in FIG. 4, and only one of them is sealed with UV resin. (This is referred to as an optical waveguide 1), and the other is filled with a solution in which a nonlinear material such as DEANST is mixed with UV resin (this is referred to as an optical waveguide 2). After that, a 45-degree mirror is provided on the two optical waveguides at a position shown in FIG. 5 by a dicing technique or the like, and the optical waveguides are attached to complete. However, the position of the 45-degree mirror is different from the material encapsulated in each optical waveguide.

  FIGS. 16A and 17A show the pattern of the optical waveguide, the installation position of the 45-degree mirror, and the material to be sealed for the optical waveguides 1 and 2, respectively. In the optical waveguide 2, two core portions are provided, but the nonlinear material is enclosed only in one. When a beam is input to the optical waveguide 1, it is guided as shown in FIG. In this configuration, the nonlinear refractive index change is caused only in the optical waveguide 2, thereby coupling the light wave mode to the other, and causing the transmission light energy to move between the two modes. The core of the optical waveguide 1 plays a role as a mere transmission path.

  FIG. 18 shows the state of beam propagation in a three-dimensional manner. The beam introduced from the port 1 of the optical waveguide 1 to the core portion is guided in the optical waveguide 1 for a while, then moved to the optical waveguide 2 by a 45-degree mirror, and then guided in the nonlinear material. Return to (Beam A). The beam introduced from the port 2 of the optical waveguide 1 to the core portion is guided through the optical waveguide 1 for a while, then moved to the optical waveguide 2 by a 45-degree mirror, passes only normal UV resin, and then enters the optical waveguide 1 again. Return (Beam B). The presence of the nonlinear optical waveguide in the optical waveguide 2 causes the transmission light energy to move between the two modes due to the coupling of the light wave modes, and this causes an optical switching operation.

  In Example 3-1, the optical waveguide length in the optical waveguide 2 causing the nonlinear optical effect was 10 cm and the core size was 5 μm × 5 μm for the directional coupler type optical switch optical waveguide. The same clad material and core material as in Example 1-1 were used. Also in Example 3-1, as a result of examining the waveguide pattern in detail, it was found that the characteristics were best when the concentration of DEANST was 13.5% by weight. It was also confirmed that even an optical waveguide having a core portion solidified by UV light irradiation has sufficient optical characteristics. The polarization maintenance rate of linearly polarized waves was able to ensure 20 dB or more necessary for the Mach-Cender switch experiment.

  In Example 3-1, a titanium sapphire laser beam (150 fs, 1 kHz) having a wavelength of 0.78 μm that passed through an OPA (optical parametric amplifier) was used, and a photomultiplier tube or a photodiode was used as a detector. As seen in the experimental results shown in FIG. 19, the output at the nonlinear optical waveguide port 3 was initially 67%, but decreased to 53% as a result of coupling caused by the third-order nonlinear optical effect. Conversely, the output at the other port 4 was initially 33%, but increased to 47% due to coupling. These changes in output indicate that a directional coupler type optical switching operation is occurring. There was no significant absorption in the experimental wavelength band, and no effect of two-photon absorption was observed.

  For use in the communication wavelength band (1.3 μm, 1.5 μm), if deuteration or fluorination of the material is performed, switching with effectively reduced absorption becomes possible (in Example 3-1). Even in the wavelength range, deuteration and fluorination have the effect of lowering absorption.) The repetition frequency is also set to a sufficiently low repetition rate (= 1 kHz) in consideration of the mixing of the thermal effect in Example 3-1, but it is also possible to perform an experiment at a higher repetition frequency than this.

Example 3-2
The directional coupler type optical switch of the present invention can also be driven by a small laser if the same idea as in Example 1-2 and Example 2-2 is advanced. In Example 3-2, an optical waveguide having a structure as shown in FIGS. 20 and 21 was produced. The propagation of the beam is the same as in Example 3-1, but the length was increased by utilizing the features of the flexible stamper technology as in Example 1-2 and Example 2-2. The port 1 of the optical waveguide 2 is filled with the same UV resin mixed with DEANST as in Example 1-1, and the port 1 is filled with only the UV resin. The effective waveguide length of the nonlinear optical waveguide made of DENAST is set to 1 m taking advantage of the present invention. Only the UV resin was enclosed in the optical waveguide 1. As the light source, a commercially available semiconductor laser (wavelength 0.83 μm, output 100 mW, pulse width 10 ns, repetition frequency 1 kHz) was used. In the optical waveguide of Example 3-2, the polarization maintaining rate of linearly polarized waves was able to ensure 20 dB or more necessary for the Mach-Cender switch experiment.

  Also in Example 3-2, the directional coupler type switch operation was confirmed, and it was found that the optical system was greatly downsized. It has been found that the same result can be obtained even with the directional coupler type optical switch according to the present invention using DMSM or SBAC in addition to DEANST. Also in this Example 3-2, by utilizing the feature of solidification, a high-speed response was possible by a pure electronic polarization effect in which a low-speed due to two-photon absorption and a thermal effect, a low-speed due to group delay dispersion, and the like were eliminated.

400 optical waveguide 401 original plate 402 clad material 403 first clad sheet (corresponding to “first resin sheet”)
403A PET film 403B Clad material 404 Soft stamper 405 Second clad sheet (corresponding to “second resin sheet”)
406A Clad part 406B Hollow part 406B 'Core part 500, 800 Optical waveguide 500A, 800A Clad part 500B, 800B Core part

Claims (9)

  An optical waveguide having a resinous cladding portion and a core portion made of a solid medium, wherein the solid medium is an ultraviolet curable resin.   The optical waveguide according to claim 1, wherein an organic material exhibiting a nonlinear optical effect is mixed in the ultraviolet curable resin. An optical waveguide having a resinous cladding and first and second cores made of a solid medium,
An optical waveguide, wherein the solid medium is an ultraviolet curable resin, and an organic material exhibiting a nonlinear optical effect is mixed only in the solid medium of the first core portion. A method for producing an optical waveguide having a resinous cladding part and a core part made of a solid medium,
Providing a resinous cladding having a hollow portion;
Introducing a UV curable resin into the hollow portion by capillary action;
And a step of solidifying the ultraviolet curable resin introduced into the hollow part by ultraviolet irradiation to form a core part.   The manufacturing method according to claim 4, wherein an organic material exhibiting a nonlinear optical effect is mixed in the ultraviolet curable resin. The step of providing the resinous clad part having the hollow part includes:
Applying a resin on the original plate;
Applying a first resin sheet on the resin by a laminating method to produce a soft stamper having a recess;
6. The method according to claim 4, further comprising: pasting a second resin sheet to a surface of the soft stamper on which the concave portion is formed, and providing the clad portion having the hollow portion. .   In a nonlinear optical device in which gate light is incident on an optical waveguide together with incident light through a polarizer, and the incident light that has passed through the optical waveguide is extracted as outgoing light through an analyzer, the optical waveguide includes: A non-linear optical device, which is the optical waveguide according to 2.   The incident laser beam is demultiplexed, one of the demultiplexed light waves is passed through the first core portion including the nonlinear material, a phase shift is applied, and the light is demultiplexed into the second core portion not including the nonlinear material. 4. The nonlinear optical device that obtains output light in which input light is modulated by being combined with the other light wave that has not been given a phase shift, wherein the first core part and the second core part are described in claim 3. A nonlinear optical device comprising first and second core portions of the optical waveguide.   Of the adjacent first and second core portions, only the first core portion includes a nonlinear material, and the light wave mode incident on one core portion is combined with the light wave mode incident on the other core portion. 4. The optical waveguide according to claim 3, wherein the first core portion and the second core portion are optical waveguides that turn on and off light energy from an emission end by movement of transmitted light energy that occurs between both modes. 5. A non-linear optical device, characterized in that the first and second core portions of the non-linear optical device.

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