JPH10319445A - Thermo-optic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a digital thermo-optic switch which has excellent stability against heat, low loss of the optical waveguide in 1.55 to 1.58 μm region and excellent wavelength selectivity and which can be produced at a low cost by constituting a polymer optical branch circuit of a polymer obtd. by hardening a specified copolymer by heat. SOLUTION: Relating to a digital thermo-optical switch comprising a polymer optical branch circuit and a heating element, the polymer optical branch circuit is produced from a polymer which is obtd. by hardening a copolymer having units expressed by formulae I to IV as the structural components and <=10000 weight average mol.wt. by heat. In formulae, R1 is a deuterium phenyl group or halogenated phenyl group expressed by C6 X5 (X is deuterium or halogen), Z is hydroxy group or alkoxy group expressed by OCm H2m+1 (m is an integer <=3), R2 is an alkyl group, deuterium alkyl group or halogenated alkyl group expressed by Cn H2n+1 (Y is hydrogen, deuterium or halogen and (n) is a positive integer).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital thermo-optic device for a high-performance and low-cost wavelength division multiplexing (WDM) optical communication network. More specifically, a digital thermo-optic switch and an optical add / drop multiplexer (excellent in heat stability, low in optical waveguide loss in the 1.55 to 1.58 μm band, excellent in wavelength selectivity, and low in manufacturing cost) The present invention relates to an optical filter having an ADM function.

[0002]

2. Description of the Related Art As is well known, a wavelength division multiplexing (WDM) optical communication system aims to increase transmission capacity by multiplexing a plurality of optical signals having different wavelengths within a wavelength band that can be transmitted through an optical transmission line. Optical communication system. The mainstream of optical communication in the future is being decided on wavelength multiplexing optical communication. Recently, the practical use of technology using light waves as a communication medium has begun to spread not only in the field of signal link, ie, transmission, but also in the field of signal nodes, ie, switching, and even in the field of signal processing.

At present, test beds for wavelength division multiplexing optical communication are being implemented in the United States and Europe. There is a rigorous brushing up for practical use of various device components such as lasers, amplifiers, switches, filters, and wavelength converters. At present, the only thing that has yet to emerge is the laser and the amplifier. For example, regarding switches, those based on electro-optic effect, thermo-optic effect, Stark effect, and acousto-optic effect are competing. Speaking of materials, ferroelectric crystals, glass,
Various switches composed of polymers, semiconductors, etc. are competing. In the future, parts with excellent characteristics and high practicality will be selected.

The above-mentioned wavelength multiplexing node includes, specifically, an optical cross connect for switching an optical path as light, a so-called add / drop filter for entering and exiting a specific wavelength signal assigned on a user basis. Refers to the wavelength selection gate, called.

The changeover switches that are key to the optical cross-connect system not only have high switching performance, but also have a simple control system for practical use, have a wide operation tolerance (tolerance), and have a large scale. There is a demand for a device having high integration and compactness corresponding to the above.

In addition, the optical filter for realizing the optical add / drop function is used in a hierarchy one step closer to the user than the optical cross connect because of the network configuration, so that it is easier to handle than the optical cross connect switch. And there is a demand for devices with high economical efficiency.

[0007] Hereinafter, for each of the above-described optical waveguide type thermo-optical switch and optical filter, their prior art will be described.
This will be described in more detail.

Conventionally, an inorganic glass excellent in transparency has been mainly used as an optical waveguide material. However, inorganic glass has problems such as being heavy and easy to break, and high production cost. Recently, instead of inorganic glass, an optical communication wavelength range (1.3 μm and 1.55 μm) has been used.
There is a growing movement to manufacture single-mode optical waveguide components using a transparent polymer having a window in the band. A polymer material is easy to form a thin film by a spin coating method, a dip method, or the like, and is suitable for manufacturing a large-area optical waveguide. In addition, the fact that manufacturing is basically a low-temperature process and that it is easy to apply to replication, such as mass production using molds, has the potential for cost reduction compared to glass-based or semiconductor-based optical waveguides. high. For these reasons, optical integrated circuits used in the field of optical communication,
It is expected that optical waveguide components such as optical wiring boards used in the field of optical information processing can be manufactured in large quantities and at low cost using polymer optical materials, and polymethyl methacrylate (PMM)
Various transparent polymers such as A) have been proposed, and research and development of optical waveguides are being vigorously pursued.

Further, among various optical waveguide devices, the digital thermo-optical switch in which both the core and the clad are made of a polymer is superior in that the thermo-optic constant of the polymer material is one digit larger than that of the inorganic glass material. It is an optical device that makes full use of, and has been actively researched and developed by various organizations as a promising candidate for an optical path switch used in an optical cross-connect or an optical add / drop multiplexer in a lightwave network. Recent advances have been described, for example, by W.W. W. Horsthuis et al., ECOC9
5, pages 1059-1062 (1995); Kyle
(N. Keil) et al., Electronics Letters.
Lett.), Vol. 31, pp. 403-404 (199
5), Ohba et al., Proceedings of ACS P
MSE (Proc. ACS PMSE), Vol. 75, Nos. 362-363
Page (1996). In particular, the polymer thermo-optical switch reported by Hose Twice and Ohba et al. Is considered to be practically advantageous because it has larger operation tolerance and smaller wavelength dependence than the interference type phase difference switch by Kyle et al. ing.

[0010] However, the digital type requires a larger change in refractive index in principle than the interference type, so that the digital type has a large thermal load and a high heat resistance requirement for the material. For example, in the 1 × 2 thermo-optical switch module AK-SY1023SNC already marketed by Akzo, the operating temperature at which the stable operation of the crosstalk of -17 dB is guaranteed is -1.
It is specified as 7 ° C to 27 ° C. Ohba et al., PM
In a thermo-optical switch using an MA-based polymer, if the applied power exceeds 130 mW at room temperature, the reliability cannot be guaranteed because the waveguide temperature exceeds the glass transition temperature inherent to the material.

As described above, when considering the application of a polymer optical waveguide to a device, it has been recognized that heat resistance is the most important issue. In recent years, it has been considered to include an aromatic group such as a benzene ring. Alternatively, materials having improved heat resistance by using a silicone skeleton have been reported (for example, JP-A-3-43423, JP-A-4-328504). However, the introduction of such an aromatic group or rigid main chain skeleton is extremely porous for improving the heat resistance, but on the other hand, it increases the birefringence and decreases the film forming property and workability (cracking, etc.). Is remarkable. Therefore, a material satisfying well-balanced heat resistance, low birefringence, film forming property, and the like has not been known. As described above, the current polymer digital thermo-optical switch has problems depending on the material, such as heat resistance of the material and low loss property in the 1.55 to 1.58 μm band, and is truly practical. The device has not been reached.

Further, if a polymer material is used in the wavelength filter as described above, this polymer optical waveguide type wavelength filter can change the transmission center wavelength over a wide range by utilizing the thermo-optic effect. . FIG. 1 is a structural element diagram of an example of a wavelength filter using an arrayed waveguide grating.
In FIG. 1, reference numerals 1 and 2 are input and output waveguides, respectively, 3 and 4 are slab waveguides, and 5 is an arrayed waveguide composed of a number of channel waveguides having different optical path lengths. Light input from one port of the input waveguide 1 is diffracted by the slab waveguide 3 and distributed to each channel of the arrayed waveguide 5. The light propagating through the arrayed waveguides 5 is given a phase difference corresponding to the respective optical path lengths, then condensed by the slab waveguides 4 and output from the output waveguides 2. At this time, the port to be focused differs depending on the phase difference given in the arrayed waveguide 5. Therefore, from one port of the output waveguide 2, only light having a specific wavelength width is transmitted and output. The central wavelength λ _{0 of} light transmitted from the center port of the input waveguide 1 is represented by the following equation (1):

[0013]

[Number 1] During _{λ 0 = (n c · ΔL} ) / N ... (1) ( wherein, n _c is the effective refractive index of each channel of the arrayed waveguide 5, [Delta] L is the optical path length difference between respective channels, N is the Diffraction order). From equation (1), it can be seen that the transmission center wavelength is proportional to the equivalent refractive index of the arrayed waveguide 5. Since a polymer material has a thermo-optic constant one order of magnitude greater than that of an inorganic glass material, a wavelength filter using a polymer material has a wavelength of 1 to 1 compared with an inorganic glass material when the center wavelength is changed by using the thermo-optic effect. An order of magnitude larger wavelength tunable range is obtained. For example, in equation (1), when ΔL = 126 μm and N = 119, the temperature change of the equivalent refractive index of the PMMA-based polymer is −1.
Since it is 1 × 10 ⁻⁴ / ° C., the center wavelength is −0.12 nm.
/ ° C. Therefore, 5
With a temperature change of about 5 ° C., the center wavelength can be changed by about 6.4 nm. This center wavelength change is 1.55μ
When converted to frequency in the m wavelength band, it corresponds to a change of 800 GHz. In the case of an inorganic glass material, the temperature change required to obtain this frequency change is about 550 ° C., which is not practical. For these reasons, an arrayed waveguide grating wavelength filter having a wide wavelength tunable range has been fabricated using a PMMA-based polymer, and has been reported [Japanese Journal of Applied Physics (Jap.
anese Journal of Applied Physics), Volume 34, Volume 6
416-6422 (1995)].

However, in the wavelength filter using the PMMA polymer reported in the above report, since the glass transition temperature of the material is about 100 ° C., when the center wavelength is changed by the temperature change, the heat resistance is insufficient. Had the disadvantage that Therefore, the temperature change range of the wavelength filter is limited to about 80 ° C. or less, and as a result, the wavelength variable range is also limited. For example, in the equation (1), when n _c = 1.46, ΔL = 126 μm, and N = 119, the free spectral range (FS
R) is 12.9 nm, which is approximately 16
00 GHz, that is, 8 channels at 200 GHz intervals or 16 channels at 100 GHz intervals. Here, the FSR refers to a wavelength interval up to the transmission wavelength peak of the next diffraction order. That is, the wavelength of light that can be selected by the wavelength filter is limited to the wavelength range of the FSR. Therefore, if a wavelength filter whose center wavelength is variable over the entire FSR can be realized, by tuning the center wavelength of the wavelength filter, an arbitrary wavelength can be extracted within a range that can be selected by the wavelength filter. However, the temperature change of the equivalent refractive index of the PMMA-based polymer is -1.
1 × 10 ⁻⁴ / ° C., PMMA from room temperature (25 ° C.)
The temperature change up to the upper limit (80 ° C.) of the usable temperature, that is, the variable range of the center wavelength at the temperature change of 55 ° C. is 6.4.
Therefore, tuning of the center wavelength over the entire FSR was difficult. Therefore, in order to realize a wavelength filter whose center wavelength is variable over the entire FSR, development of a polymer optical waveguide material having higher heat resistance has been desired.

[0015] For these reasons, in recent years, materials having improved heat resistance by incorporating an aromatic group such as a benzene ring or using a silicone skeleton have been reported (for example, Japanese Patent Application Laid-Open No. 3-43423, Kaihei 4-328
No. 504). However, the introduction of aromatic groups and rigid main-chain skeletons is extremely effective in improving heat resistance, but on the other hand, increases the birefringence and decreases film formability and workability (cracking, etc.). The tendency to bring about is remarkable. Therefore, a material satisfying well-balanced heat resistance, low birefringence, film forming property, and the like has not been known. Therefore, the current polymer waveguide type wavelength filter still has a problem in the heat resistance of the material.

[0016]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional digital thermo-optical switch and optical ADM filter and to provide a high-performance and low-cost digital optical switch for a WDM network. And an optical filter.

[0017]

According to the present invention, a digital thermo-optical switch and an optical ADM filter are each provided with heat resistance and low loss in a functional portion such as a branch formed in the middle of an optical circuit as a component. By using a silicone material with excellent low birefringence, sufficient heat stability for practical use,
It is a feature of the present invention to obtain a digital thermo-optical switch and an optical ADM filter that realize low loss, wavelength selectivity, and low cost in the 1.55 to 1.58 μm band.

The digital thermo-optical switch according to the present invention is a digital thermo-optical switch comprising a polymer optical branch and a heating element, wherein the following formulas (I) and (II) are used.
(III) and (IV):

[0019]

Embedded image

[In the formulas (I) and (II), R ₁ is a deuterated phenyl group or a halogenated phenyl group represented by C ₆ X ₅ (X represents deuterium or halogen),
Z is a hydroxyl group or OC _m H _{2m + 1} (m is an integer of 3 or less)
An alkoxy group represented by the formula (III) and (I
In V), R ₂ is an alkyl group, a deuterated alkyl group or a halogenated alkyl group represented by C _n Y _{2n + 1} (Y is hydrogen, deuterium or halogen, and n is a positive integer) , Z is a hydroxyl group or an alkoxy group represented by OC _m H _{2m + 1} (m is an integer of 3 or less)], and the weight average molecular weight is 1000
The polymer optical branch is formed from a polymer obtained by thermosetting a copolymer having a molecular weight of 0 or less.

Further, the polymer optical waveguide type wavelength filter of the present invention is a polymer optical waveguide wavelength filter having a polymer optical waveguide having a wavelength filter function, wherein the following formulas (I), (II) and (III) and (IV):

[0022]

Embedded image

[In the formulas (I) and (II), R ₁ is a deuterated phenyl group or a halogenated phenyl group represented by C ₆ X ₅ (X represents deuterium or halogen),
Z is a hydroxyl group or OC _m H _{2m + 1} (m is an integer of 3 or less)
An alkoxy group represented by the formula (III) and (I
In V), R ₂ is an alkyl group, a deuterated alkyl group or a halogenated alkyl group represented by C _n Y _{2n + 1} (Y is hydrogen, deuterium or halogen, and n is a positive integer) , Z is a hydroxyl group or an alkoxy group represented by OC _m H _{2m + 1} (m is an integer of 3 or less)], and the weight average molecular weight is 1000
The polymer optical waveguide is made of a polymer obtained by thermosetting a copolymer having a molecular weight of 0 or less.

The polymer optical waveguide wavelength filter further comprises a temperature controller for controlling the temperature of the polymer waveguide so as to arbitrarily separate or mix optical signals of a specific wavelength. Is also good.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION

(Digital thermo-optical switch) The present inventors have solved the problems of the conventional digital thermo-optical switch by:
When a digital thermo-optic switch was fabricated using a thermosetting silicone oligomer that can achieve both high heat resistance and low birefringence, it has no cracking, has extremely transparent waveguide characteristics, and has polarization. It has been found that digital switching operation that is independent and extremely stable even at high temperatures can be obtained. The digital thermo-optical switch according to the present invention,
This is based on such knowledge.

The thermosetting silicone oligomer has excellent heat resistance because it is a material having a ladder type silicone structure as a molecular skeleton. In addition, since hydrogen of the C—H bond contained in the side chain is replaced by deuterium or halogen, absorption in the near infrared region caused by the overtone or bond sound of the expansion or contraction of the C—H bond or the bending vibration. , Has been greatly reduced. Further, by using a material of a type that thermally cures an oligomer having a weight-average molecular weight of 10,000 or less, optical anisotropy that occurs during the formation of a thin film can be suppressed, and the birefringence of the polymer material obtained after thermal curing Has been greatly reduced.

That is, the present invention uses a polymer optical waveguide material obtained by thermosetting a silicone oligomer as an optical branching furnace in a polymer digital thermo-optical switch, thereby realizing practical use with high heat resistance. It is possible to realize a typical digital thermo-optical switch.

Hereinafter, the contents of the digital optical switch according to the present invention will be specifically described.

The silicone oligomer used in the optical switch of the present invention is, for example, a partially laddered silicone oligomer obtained by co-hydrocondensing deuterated phenyltrichlorosilane and methyltrichlorosilane, and having a weight average molecular weight of 10,000 or less. And By thermosetting this, a cured film having high heat resistance, small birefringence, and high cracking resistance can be obtained. As for thermosetting conditions, from 150 ° C to 25
Heating at 0 ° C. for about 1 hour to several hours is desirable.

When a thermo-optical switch is manufactured using a thermosetting silicone having high heat resistance and excellent cracking resistance, the process can be performed as follows.

First, the refractive index of the silicone oligomer is adjusted in accordance with the waveguide mode condition required for the optical branch waveguide in the thermo-optical switch, and the refractive index difference is precisely controlled as the core / cladding material. At least two silicone oligomers are provided. The magnitude of the refractive index difference is determined according to the mode of the light to be guided and the dimensions of the core. square,
It is desirable that the refractive index difference is around 0.3%. In the case of the thermosetting silicone used in the present invention, the refractive index of the finally obtained optical waveguide thin film is adjusted by the composition of the raw materials, that is, in the above example, the mixing ratio of deuterated phenyltrichlorosilane and methyltrichlorosilane. It is possible to

Next, a clad material whose refractive index has been adjusted is coated on a substrate such as silicone and cured to form a lower clad.

Next, a core material is applied on the lower clad and cured. Here, since the clad material and the core material are applied in an oligomer state, the orientation of molecular chains during film formation is suppressed, and birefringence is reduced.

Subsequently, a layer serving as an etching mask is formed on the core, and processed into a waveguide pattern by photolithography or the like. As an etching mask, an organic photoresist or a metal is used. Further, the core is processed into a desired optical branching waveguide pattern by reactive ion etching, and an upper clad is applied thereon and cured.
The optical branching waveguide manufactured using the thermosetting silicone in this manner has excellent heat resistance, and is 1.3 μm and 1.55 μm.
It is an ideal optical waveguide that is transparent in both communication wavelength bands of m and has no polarization dependence.

Further, a thin metal film is deposited on the cladding of the optical branching waveguide by sputtering and patterned by photolithography or the like to form a heater electrode.
The polymer digital thermo-optical switch manufactured in this way has excellent heat resistance and exhibits ideal digital switching characteristics without polarization dependence.

(Polymer Optical Waveguide Type Wavelength Filter) The present inventors have solved the problem of the conventional wavelength filter by
When a polymer optical waveguide type wavelength filter was manufactured using a thermosetting silicone oligomer capable of achieving both high heat resistance and low birefringence, it did not crack and had extremely transparent waveguide characteristics. It has been found that the wave dependence is small and extremely stable characteristics can be obtained even at high temperatures. Furthermore, the present inventors fixed the wavelength filter on a temperature controller, and examined the temperature change of the center wavelength in detail, and found that a polymer optical waveguide manufactured using a thermosetting silicone oligomer was It was found to have a relatively large thermo-optic constant of -1.7 × 10 ⁻⁴ / ° C. As a result, the present inventors have found that, in the wavelength filter, the center wavelength can be tuned over a wide range corresponding to the temperature change of the refractive index using thermo-optic curing,
The wavelength filter of the present invention has been completed. Here, the thermosetting silicone oligomer has excellent heat resistance because it is a material having a ladder-type silicone structure as a molecular skeleton. In addition, since hydrogen of the C—H bond contained in the side chain is replaced by deuterium or halogen, absorption in the near infrared region caused by the overtone or bond sound of the expansion or contraction of the C—H bond or the bending vibration. , Has been greatly reduced. further,
By using a type of material that thermally cures an oligomer having a weight average molecular weight of 10,000 or less, optical anisotropy that occurs during thin film formation can be suppressed, and the birefringence of the polymer material obtained after thermal curing is significantly increased. Has been reduced to

That is, the present invention provides a polymer optical waveguide having high heat resistance and a wide variable wavelength range by forming an optical waveguide type wavelength filter using a polymer obtained by thermally curing a silicone oligomer. This makes it possible to realize a waveguide type wavelength filter.

Hereinafter, the contents of the polymer optical waveguide type wavelength filter according to the present invention will be specifically described.

The silicone oligomer used in the wavelength filter of the present invention is, for example, a partially laddered silicone oligomer obtained by co-hydrocondensing deuterated phenyltrichlorosilane and methyltrichlorosilane, and having a weight average molecular weight of 10,000 or less. And By heat curing this, high heat resistance,
A cured film having low birefringence and high cracking resistance can be obtained. In terms of thermosetting conditions, from 150 ° C to 2
Heating at 50 ° C. for 1 hour to several hours is desirable.

In the case where an optical waveguide wavelength filter is manufactured using a thermosetting silicone having high heat resistance and excellent cracking resistance, the process can be performed as follows. First, the refractive index of the silicone oligomer is adjusted, and at least two types of silicone oligomers having a precisely controlled refractive index difference are prepared as core / cladding materials. The magnitude of the difference in refractive index is determined according to the dimensions of the core. Typically, when the shape of the core is a square of 8 μm square, the difference in refractive index is about 0.3 to 1%. In the case of the thermosetting silicone used in the present invention, the refractive index of the finally obtained optical waveguide thin film is adjusted by the composition of the raw materials, that is, in the above example, the mixing ratio of deuterated phenyltrichlorosilane and methyltrichlorosilane. It is possible.

Next, a clad material whose refractive index has been adjusted is coated on a substrate such as silicone and cured to form a lower clad.

Next, a core material is applied on the lower clad and cured. Here, since the clad material and the core material are applied in an oligomer state, the orientation of molecular chains during film formation is suppressed, and birefringence is reduced.

Subsequently, a layer serving as an etching mask is formed on the core, and processed into an optical waveguide pattern constituting a wavelength filter by photolithography or the like. Such an optical waveguide pattern includes an asymmetric Mach-Zehnder interferometer in addition to the arrayed waveguide grating shown in FIG. As an etching mask, an organic photoresist or a metal is used. Further, the core is processed into a desired optical waveguide pattern by reactive ion etching, and an upper clad is applied thereon and cured. The optical waveguide type wavelength filter manufactured using the thermosetting silicone as described above has excellent heat resistance, and is 1.3 μm and 1.55 μm.
Transparent in both communication wavelength bands, polarization dependence is small,
It has a wide wavelength tunable range.

In the wavelength filter of the present invention, the temperature controller further provided may be a heater having a feedback circuit, a Peltier element, or the like. In order to suppress fluctuation of the transmission center wavelength due to temperature fluctuation,
It is desirable that the temperature controller be capable of controlling the temperature fluctuation within ± 1 degree.

[0045]

Embodiments of the present invention will be described below. Examples 1 to 3 below are examples where the thermo-optical device of the present invention is an optical switch, and Examples 4 and 5 are examples where the thermo-optical device is an optical filter.

Example 1 Deuterated phenyltrichlorosilane and methyltriethoxysilane (molar ratio: 53:47) were dissolved in dehydrated toluene and mixed with water-THF-toluene while stirring in an ice bath. The solution was slowly dropped.
After reacting for 5 hours, the organic layer was separated, washed with water while neutralizing, and after standing, the insoluble matter was filtered off from the separated organic layer and dried. The organic solvent was completely distilled off under reduced pressure, the obtained white solid was dissolved in ethanol, a small amount of hydrochloric acid was added, and the mixture was heated under reflux. Ethanol was distilled off under reduced pressure, and the residue was sufficiently washed while neutralizing with a toluene-water system. The organic layer was separated and dried, and toluene was distilled off under reduced pressure to obtain a white solid. Molecular weight 3000
Before and after. The thermogravimetric analysis result of the thermoset of this material
FIG. 2 shows a comparison with that of MMA. This fully demonstrates the thermal stability of the thermoset silicones of the present invention.
The clad material when the above-mentioned silicone oligomer was used as the core material was synthesized as follows. A white solid was obtained from deuterated phenyltrichlorosilane and methyltriethoxysilane (at a molar ratio of 1: 1) in the same manner as in the synthesis of the core material. The molecular weight was around 3600. A spin-coated film was prepared by using each of the core material and the clad material as a diglyme solution, thermally cured at 250 ° C. for 1 hour, and the refractive index in the optical communication wavelength range was measured. Table 1 shows the measurement results of the refractive index.

[0047]

[Table 1]

The above two types of silicone oligomers are
A Y-branch optical waveguide serving as a clad was manufactured. First, a silicone oligomer for cladding was applied on a silicone substrate by spin coating to form a film. At this time, if the film thickness is 2
The rotation speed of the spin coater was adjusted to be 0 μm.
The formed thin film was cured by heating at 200 ° C. for 2 hours to form a lower clad layer. Then, a silicone oligomer for a core was formed thereon under the condition of a thickness of 8 μm. Cured at 200 ° C. for 2 hours. Subsequently, a copper thin film was deposited by sputtering, and a Y-branch optical waveguide mask pattern was formed by photolithography and ion milling. The total length of the branch road was 2 cm. Further, the core layer other than the mask pattern was removed by reactive ion etching to form a rectangular core ridge having a width of 8 μm and a height of 8 μm. After removing the etching mask, a silicone oligomer for cladding was applied thereon and cured as in the case of forming the lower cladding to form a buried channel optical waveguide having a core / cladding structure. The thickness of the upper clad was 10 μm from the upper surface of the core.

Further, a gold thin film was deposited on the upper clad of the Y-branch optical waveguide by sputtering. Finally, the gold thin film was patterned by photolithography and ion milling to form a heater electrode. FIGS. 3 to 5 show conceptual diagrams of the manufactured digital thermo-optical switch. That is, FIG. 3 is a sketch drawing showing the configuration of an example of the polymer digital thermo-optical switch of the present invention. FIG. 4 is a plan view of the switch shown in FIG. FIG. 5 is a cross-sectional view of FIG.
It is sectional drawing of A 'cut surface. 3 to 5, reference numeral 11 denotes an input waveguide of the optical branch, and reference numerals 12 and 13 denote output waveguides of the optical branch. Reference numerals 14 and 15 are heater electrodes.

A polarization-maintaining optical fiber was butt-connected to the input waveguide 11 of the optical branch, and a single-mode optical fiber was butt-connected to the output waveguides 12 and 13 of the optical branch, and laser light was input from the optical fiber on the input side. As described above, first, when the insertion loss was measured in a state where no current was applied to the heater electrodes 14 and 15, the wavelength was 1.3 μm.
Was 3.5 dB and 4.0 dB at a wavelength of 1.55 μm. The polarization dependence of the insertion loss was within 0.1 dB. From these results, the optical branch used in the present invention is:
It has been demonstrated that the waveguide has a low insertion loss, a small polarization dependence, and a very good quality single mode waveguide.

Subsequently, a current was applied to the heater electrode 15 on the output waveguide 13 to heat it. FIG. 6 shows the result of measuring the relationship between the heating power and the output light intensity at a wavelength of 1.55 μm at this time. That is, FIG. 6 is a diagram showing switching characteristics of the digital thermo-optical switch according to the present invention. In FIG. 6, the vertical axis represents the output light intensity (dB), and the horizontal axis represents the applied power (m).
W). In FIG. 6, black squares indicate the output light intensity from the output waveguide 13, and white circles indicate the output light intensity from the output waveguide 12. As can be seen from FIG. 6, an optical switch having switching characteristics of an insertion loss of 1 dB and an extinction ratio of 30 dB or more is realized with an applied power of 60 mW. The polarization dependence of the insertion loss was within 0.1 dB.

Next, a current was applied to the heater electrode 14 on the output waveguide 12 to heat it. At this time, almost the same result as the characteristic obtained by exchanging the output light intensity from the output waveguides 12 and 13 in FIG. 6 was obtained.

Further, a similar experiment was conducted using a wavelength tunable laser light source in the 1.55 μm band, and the wavelength dependence of characteristics when this switch was operated at 60 mW was measured. FIG. 7 shows the output light intensity of each port waveguide. From this, it has been found that the optical switch of the present invention maintains characteristics in a wide wavelength range of 1.55 μm band and can be applied to WDM applications using a wide wavelength range.

A similar experiment was conducted at a wavelength of 1.3 μm, and the result was equivalent to 1.55 μm, that is, 60 m.
With an electric power of W, an insertion loss of 0.5 dB and an extinction ratio of 30 dB or more were obtained.

Example 2 (Optical Switch) A core material and a clad material were synthesized from deuterated phenyltrichlorosilane and methyltriethoxysilane according to the method described in Example 1. However,
The molar ratio of the monomers was 80:20 for the core material and 74:26 for the cladding material. The weight average molecular weight of both the core material and the clad material was 2,000.
Using these core / cladding materials, a polymer digital thermo-optical switch was manufactured according to the method described in Example 1. When the switching characteristics of this optical switch were compared at room temperature with humidity of 10%, 50%, and 90%, almost no influence of humidity was observed, and the insertion loss was 1d.
B, extinction light was 30 dB or more. In addition, 60mW
Heat cycle test for continuous operation by driving (-1
(0 ° C. to 60 ° C.), the insertion loss was almost unaffected and remained constant.

Example 3 (Optical Switch) A core material and a clad material were synthesized from deuterated phenyltrichlorosilane and methyltriethoxysilane according to the method described in Example 1. However,
The molar ratio of the monomers was 30:70 for the core material and 28:72 for the cladding material. The weight average molecular weight of both the core material and the clad material was 8,000.
Using these core / cladding materials, a polymer digital thermo-optical switch was manufactured according to the method described in Example 1. When this optical switch was operated at a temperature of 100 ° C., the extinction ratio was 30 dB or more.

Example 4 (Optical Filter) In dehydrated toluene, deuterated phenyltrichlorosilane and methyltriethoxysilane (molar ratio: 6)
0:40) was dissolved and slowly added dropwise to a water-tetrahydrofuran (THF) -toluene mixture stirred in an ice bath. After reacting for 5 hours, the organic layer was separated, washed with water while neutralizing, and after standing, the insoluble matter was filtered off from the separated organic layer and dried. The weight average molecular weight was 5,000.

When the above silicone oligomer was used as the core material, the clad material was synthesized as follows. A white solid was obtained from deuterated phenyltrichlorosilane and methyltriethoxysilane (molar ratio: 52:48) in the same manner as in the synthesis of the core material described above. The weight average molecular weight is 5000
Met. A spin-coated film was prepared by using each of the core material and the clad material as a methyl isobutyl ketone (MIBK) solution, heated at 200 ° C. for 2 hours, thermally cured, and the refractive index in an optical communication wavelength range was measured. Table 2 shows the measurement results of the refractive index.

[0059]

[Table 2]

The above two types of silicone oligomers are
An arrayed waveguide grating type wavelength filter to be used as a clad was fabricated. First, a silicone oligomer for cladding was applied on a silicone substrate by spin coating to form a film.
At this time, the rotation speed of the spin coater was adjusted so that the film thickness became 16 μm. The formed thin film was cured by heating at 200 ° C. for 2 hours to form a lower clad layer. Next, a silicone oligomer for a core was formed on this under a condition of a thickness of 8 μm, and cured at 200 ° C. for 2 hours. Subsequently, a copper thin film was deposited by sputtering, and a mask pattern of an arrayed waveguide grating was formed by photolithography and ion milling. Furthermore, by reactive ion etching, the core layer other than the mask pattern is removed,
A core ridge was formed. After removing the etching mask, a silicone oligomer for cladding was applied thereon and cured as in the case of forming the lower cladding, thereby forming a buried optical waveguide having a core-cladding structure. The thickness of the upper clad was 10 μm from the upper surface of the core.

Table 3 shows the specifications of the fabricated arrayed waveguide grating wavelength filter. This wavelength filter is 30mm ×
It was cut out to a size of 40 mm and fixed on a Peltier element.

[0062]

[Table 3]

The transmission characteristics of the wavelength filter were measured while driving the Peltier element and maintaining the temperature of the optical waveguide at 25 ° C. In the 1.55 μm wavelength band, the free spectral range (FSR) of this wavelength filter is 12.8 n
m, the channel spacing between adjacent ports was 0.81 nm, and the full width at half maximum was 0.2 nm. The insertion loss is -7d
B, crosstalk between adjacent channels was -30 dB. The insertion loss was -7 dB, and the crosstalk between adjacent channels was -30 dB. When light enters from the center port of the input waveguide, the transmission center wavelength of the light emitted from the center port of the output waveguide is 1 in the diffraction order 122.
554.5 nm.

Further, the holding temperature of the optical waveguide is set to 10 ° C.
When the temperature changed to 0 ° C, the transmission center wavelengths were 15
It changed to 57.4 nm and 1544.6 nm. That is, a shift of the center wavelength corresponding to the FSR was obtained with a temperature change of 70 ° C. Furthermore, these characteristics make the optical waveguide 1
It remained unchanged after heating at 20 ° C. for 100 hours.

(Example 5) (Optical filter) In the same manner as in Example 4, materials having different molar ratios of deuterated phenyltrichlorosilane and methyltriethoxysilane as raw materials (hereinafter referred to as charge ratios) were used. They were synthesized and a thin film was formed on a silicon substrate. The refractive index of this thin film was evaluated using a prism coupler type refractometer, and the magnitude of birefringence (n _TE −) at a wavelength of 1.3 μm was measured.
n _™ ) was determined. FIG. 8 shows the results on the horizontal axis as the molar fraction of methyltriethoxysilane as the raw material.
From these results, it was found that the birefringence of the material used in the present invention changed from a positive value to a negative value depending on the charging ratio, and the birefringence became zero at a specific charging ratio.

Further, in order to confirm the elimination of the polarization dependence of the transmission center wavelength in the waveguide type wavelength filter of the present invention, the core material and the clad having the charge ratios shown in Table 4 were prepared in the same manner as in Example 4. The materials were synthesized to produce a linear optical waveguide. The polarization dependence (n _TE −n _TM ) of the transmission refractive index at a wavelength of 1.55 μm of the fabricated waveguide was measured by using Senarmont interferometry. Table 4 shows the measurement results. From these results, the optical waveguide used in the present invention, the polarization dependence of the equivalent refractive index changes from a positive value to a negative value depending on the charge ratio of the material, and the polarization dependence of the equivalent refractive index at a specific charge ratio. The absolute value was found to be zero. By using a material having this composition, a wavelength filter having no polarization dependence of the center wavelength could be manufactured.

[0067]

[Table 4]

[0068]

According to the thermo-optical device of the present invention, an optical path changeover switch and an optical filter which are indispensable for an optical cross-connect and an optical ADM in a wavelength division multiplexing optical communication network can be reduced in size while maintaining high functions. Cost can be provided. Therefore, the thermo-optical device of the present invention can greatly contribute to the development of optical communication networks, such as expansion of optical cross-connect nodes and expansion of optical access networks. Further, it can be used as an element component of a user-type optical closed network (WDM-LAN) that will be significantly developed in the future.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a conventional optical waveguide type wavelength filter.

FIG. 2 is a graph showing thermogravimetric analysis curves of thermosetting silicone and PMMA used in the optical switch of the present invention in comparison.

FIG. 3 is a perspective view of an example of a polymer digital thermo-optical switch according to the present invention.

FIG. 4 is a plan view of the optical switch shown in FIG.

FIG. 5 is a sectional view taken along the line AA ′ of FIG. 4;

FIG. 6 is a graph showing switching characteristics of the digital thermo-optical switch according to the present invention.

FIG. 7 is a graph showing the wavelength dependence of the output of the polymer digital thermo-optical switch of the present invention.

FIG. 8 is a graph showing the composition dependency of birefringence of a material used for a wavelength filter according to a fifth embodiment of the present invention.

[Explanation of symbols]

 11 Input waveguide of optical branch 12, 13 Output waveguide of optical branch 14, 15 Heater electrode

Continuing on the front page (72) Inventor Saburo Imamura 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Shoichi Hayashida 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Within Telegraph and Telephone Co., Ltd. (72) Inventor Yasuyuki Inoue 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Japan Within Telegraph and Telephone Co., Ltd. Telegraph and Telephone Corporation

Claims (3)

[Claims] 1. A digital thermo-optical switch comprising a polymer optical branch and a heating element, wherein the switch comprises the following formulas (I), (II), (III) and (IV): [In the formulas (I) and (II), R ₁ is C ₆ X ₅ (X
Represents a deuterium or halogen), Z is a hydroxyl group or an alkoxy group represented by OC _m H _{2m + 1} (m is an integer of 3 or less), In formulas (III) and (IV),
R ₂ is an alkyl group represented by C _n Y _{2n + 1} (Y is hydrogen, deuterium or halogen, and n is a positive integer);
A deuterated alkyl group or a halogenated alkyl group, and Z is a hydroxyl group or an alkoxy group represented by OC _m H _{2m + 1} (m is an integer of 3 or less)]. A polymer digital thermo-optic switch, wherein the polymer optical branch is made of a polymer obtained by thermosetting a copolymer having a weight average molecular weight of 10,000 or less. 2. A polymer optical waveguide wavelength filter having a polymer optical waveguide having a wavelength filter function, wherein the following formulas (I), (II), (III) and (IV): [In the formulas (I) and (II), R ₁ is C ₆ X ₅ (X
Represents a deuterium or halogen), Z is a hydroxyl group or an alkoxy group represented by OC _m H _{2m + 1} (m is an integer of 3 or less), In formulas (III) and (IV),
R ₂ is an alkyl group represented by C _n Y _{2n + 1} (Y is hydrogen, deuterium or halogen, and n is a positive integer);
A deuterated alkyl group or a halogenated alkyl group, and Z is a hydroxyl group or an alkoxy group represented by OC _m H _{2m + 1} (m is an integer of 3 or less)]. A polymer optical waveguide comprising a polymer obtained by thermally curing a copolymer having a weight average molecular weight of 10,000 or less, wherein the polymer optical waveguide is constituted by a polymer. 3. A temperature controller for controlling the temperature of the polymer waveguide so as to arbitrarily separate or mix optical signals of a specific wavelength. Item 3. A polymer optical waveguide wavelength filter according to item 2.