JP2005250320A - Thermo-optical optical functional component and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a thermo-optical optical functional component having a thermo-optical optical function element and an optical functional element whose optical characteristic depends upon temperature on the same substrate or the same composite substrate varies in optical function as the temperature of the whole circuit varies with the change in electric power applied to the thermo-optical optical functional element for controlling the optical function. <P>SOLUTION: Dummy thin film heaters 5a to 5d are formed on the same substrate with thermo-optical optical functional elements 6a to 6o and, for example, electric power applied to the dummy thin film heaters 5a to 5d is so adjusted that the sum of electric power applied to the thermo-optical optical functional elements 6a to 6d for controlling the optical function and electric power applied to the dummy thin film heaters 5a to 5d is held constant. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thermo-optic optical functional component in which a thermo-optic optical functional element and another optical functional element are integrated, and a control method therefor. More specifically, the stability of the optical characteristics of a thermo-optic optical functional component composed of a thermo-optic optical functional element and an optical functional element having temperature dependence on the optical characteristics is improved against fluctuations in the driving state of the thermo-optic optical functional element. It is invention regarding the circuit structure for controlling, and its control method.

  In recent years, against the background of the increase in communication traffic and the diversification of information accompanying the spread of multimedia, the demand for realizing a high-speed and large-capacity communication system is increasing, and research and development are actively conducted. Among various large-capacity communication systems, a wavelength division multiplexing (WDM) communication system that multiplexes and transmits a plurality of light beams having different wavelengths attracts great expectations as a technology for easily improving the communication capacity per optical fiber. Yes. Initially, the WDM communication system was introduced in a transmission system between two nodes called point-to-point, but recently, due to the advancement of peripheral technologies such as optical communication devices, mesh configuration and star configuration were used. It has evolved to a communication system between multiple nodes, and further to an advanced communication system that dynamically switches transmission paths between multiple nodes in accordance with traffic demands and network failure conditions. Under such circumstances, it is strongly desired to realize a highly functional WDM optical device capable of dynamically switching wavelength channels such as a variable wavelength light source, a variable wavelength filter, and a wavelength path switch.

  Under such circumstances, a PLC type optical device manufactured by a planar lightwave circuit (PLC) technology is expected as a method for realizing a high-performance WDM optical device. PLC-type optical devices are manufactured using advanced microfabrication technology such as photolithography technology and dry etching technology used in LSI fabrication, so the optical path length can be controlled with high accuracy and excellent characteristics. An optical interference circuit can be manufactured. Taking advantage of this advantage, it is composed of a high-performance optical wavelength filter such as an arrayed waveguide diffraction grating (AWG) or an asymmetric Mach-Zehnder interferometer (MZI) type optical filter, or an MZI loaded with a heater. Thermo-optic optical functional elements such as a thermo-optic optical switch (TOSW) and a variable optical attenuator (VOA) capable of dynamically switching functions have also been realized.

  Hereinafter, an AWG, an asymmetric MZI type optical wavelength filter, and a heater loaded type MZI will be described as examples of the PLC type optical device.

FIG. 7 shows a configuration diagram of the AWG. This figure is an example of a 1-input 10-output AWG. The AWG 8 includes an input channel waveguide 31, two slab waveguides 35 a and 35 b, a channel waveguide array 36 configured such that the length of the waveguide increases at regular intervals toward the outer waveguide, and an output channel guide. And a waveguide 32 (first to tenth output channel waveguides 32a to 32j). The AWG is used as a wavelength multiplexer / demultiplexer. When light that is wavelength-multiplexed is input to the input channel waveguide 31, the AWG is input to each of the output channel waveguides 32 (first to tenth output channel waveguides 32 a to 32 j). Optical signals with different wavelengths are output. When the input channel waveguide 31 is disposed on the center line of the first slab waveguide and the output channel waveguide 32e is disposed on the center line of the second slab waveguide, the input channel waveguide 31 and the output The wavelength of light that is optically coupled with low loss between the channel waveguides 32e is referred to as a center wavelength λ _c , the effective refractive index of the channel waveguide array 36 is n _e , and the waveguide between adjacent waveguides of the channel waveguide array 36 is guided. When the difference in waveguide length is ΔL and the diffraction order is m, it is expressed by (Expression 1).

Here, considering the change amount of the center wavelength when the temperature change occurs, the change amount Δλ _c of λ _c caused by the temperature change ΔT is expressed by (Equation 2).

In (Expression 2), the first term on the right side represents the center wavelength change caused by the temperature change of the refractive index, and the second term on the right side represents the center wavelength change caused by the physical change of the waveguide length due to the thermal expansion of the waveguide. Represents. C in the equation is a coefficient representing the temperature dependence of the center wavelength, and Δλ _c is represented by a product of ΔT and C.

Next, an asymmetric MZI type optical wavelength filter will be described. The structure of the asymmetric MZI type optical wavelength filter is shown in FIG. The asymmetric MZI optical wavelength filter includes input channel waveguides 31a and 31b, two couplers 33a and 33b, two arm waveguides 34a and 34b having different lengths, and output channel waveguides 32a and 32b. The The light input from the input channel waveguide 31a is branched to the arm waveguides 34a and 34b by the first coupler 33a, propagates through the arm waveguides 34a and 34b, and is then combined by the second coupler 33b to be output channel guided. Output from the waveguides 32a and 32b. Here, assuming that the two couplers 33a and 33b are both 3 dB couplers, when light having an intensity of | E ₀ | ² is incident on the input channel waveguide 31a, the light output to the output channel waveguide 32a. The light intensity | E ₁ | ² and the light intensity | E ₂ | ² of the light output to the output channel waveguide 32b are expressed by (Expression 3) and (Expression 4), respectively.

  Here, Δφ is an optical phase difference generated in light propagating through the two arm waveguides 34a and 34b having different lengths, and is expressed by (Equation 5).

Here, [Delta] L is the arm waveguides 34a, the difference between the waveguide length of 34b, n _e is the effective refractive index of the arm waveguide, lambda is the wavelength of the propagation light. As can be seen from (Equation 3) and (Equation 4), with M as an integer, light having an optical wavelength at which Δφ = Mπ is output to the output channel waveguide 32b, and the optical wavelength at which Δφ = (M + 1/2) π is obtained. Is output to the output channel waveguide 32a. Further, as can be seen from (Equation 5), Δφ continuously changes as the wavelength changes, so that it operates as an optical wavelength filter in which the output channel waveguide from which light is output is periodically switched with respect to the wavelength change. The optical wavelength λ _m when the interference order satisfies the interference condition of m and the light is output from the output channel waveguide 32b is expressed by an equation in which λ _c in (Equation 1) is replaced by λ _m , The change amount of λ _m with respect to the temperature change is expressed by an equation in which λ _c in (Equation 2) is replaced by λ _m . Also in the case of the asymmetric MZI type optical filter, as in the case of AWG, the amount of change of λ _m with respect to the temperature change is expressed by the product of the temperature change amount ΔT and the coefficient C representing the temperature dependence.

  As described above, the AWG and the asymmetric MZI type optical wavelength filter are described by way of example. In the case of the PLC type optical wavelength filter, the optical wavelength characteristic with respect to temperature change shifts in proportion to C, and the value of C is a quartz glass waveguide. Is about 0.01 [nm / ° C.], is about −0.5 [nm / ° C.] in the case of a polymer waveguide (in the case of a PMMA waveguide), and is about 0.00 in the case of a semiconductor waveguide. It is about 1 [nm / ° C.].

  Further, although detailed explanation is omitted, the semiconductor laser also has a large temperature dependency in characteristics such as the oscillation light wavelength, the oscillation threshold current, and the output power. For example, in a Fabry-Perot semiconductor laser in which an active layer is sandwiched between mirrors, the refractive index of the semiconductor material constituting the active layer changes when the temperature changes, the resonance condition changes, and the gain spectrum of the active layer changes in wavelength. Since it shifts on the axis, the oscillation wavelength changes. The temperature dependence of the oscillation wavelength of the semiconductor laser is about 0.4 nm with respect to a temperature change of 1 ° C.

Next, a heater loaded type MZI used as TOSW or VOA will be described as an example of a thermo-optic light functional element. FIG. 9 shows a configuration diagram of the heater loading type MZI. FIG. 2A is a plan view seen from above, and FIG. 2B is a cross-sectional view taken along the line AA ′ in FIG. The heater-loaded MZI includes input channel waveguides 31a and 31b, two couplers 33a and 33b, two arm waveguides 34a and 34b, output channel waveguides 32a and 32b, and a thin film heater 4. . The light input from the input channel waveguides 31a and 31b is branched to the arm waveguides 34a and 34b by the first coupler 33a, propagated through the arm waveguides 34a and 34b, and then multiplexed by the second coupler 33b to be output. Output from the channel waveguides 32a and 32b. If incident ^second light, the light intensity of the light output to the output channel waveguides 32a | | light intensity input channel waveguide 31a is | E ₀ E ₁ | ² and the light output to the output channel waveguide 32b The light intensity | E ₂ | ² is expressed by the same expression as (Expression 3) and (Expression 4), respectively. If the heater loaded type MZI, the difference between the waveguide length of the arm waveguide and [Delta] L, the effective refractive index of the arm waveguide and n _e, the optical wavelength of the propagating light is lambda, a power applied to the thin film heater 4 P Assuming [W], the optical path length difference Δφ between the arm waveguides 34a and 34b is expressed by (Expression 6).

  Here, dφ / dP is the amount of optical phase change given to the light propagating through the arm waveguide 34a by applying 1 W power to the thin film heater 4, and this value is the temperature dependence of the refractive index of the waveguide material. And parameters such as the structure of the waveguide. In the case of the heater-loaded MZI, as can be seen from (Equation 3) and (Equation 4), when M is an integer and Δφ is changed by applying power to the thin film heater and Δφ = Mπ is adjusted, the input channel waveguide The light incident from 31a is output to the output channel waveguide 32b, and when adjusted to Δφ = (M + 1/2) π, the light incident from the input channel waveguide 31a is output to the output channel waveguide 32a, and Δφ is intermediate When adjusted to a specific value, light can be output to the two output channel waveguides 32a and 32b at a light intensity ratio corresponding to the value of Δφ. For example, when the optical path lengths of the two arm waveguides 34a and 34b when no power is applied are equal, that is, when the first term on the right side of (Expression 6) is zero, P = (π / 2) / ( It functions as an optical switch that switches the output channel waveguide from which light is output depending on whether or not power of dφ / dP) is applied between 32a and 32b, and P = 0 to (π / 2) / (dφ / dP ) In the range of 0 to ∞ dB by adjusting the power in the range of 0) to ∞ dB continuously by the light incident from the input channel waveguide 31a until reaching the output channel waveguide 32b. Functions as an optical attenuator.

  The PLC type device described above has excellent features as an implementation form of an optical device for optical communication such as easy connection with a single mode optical fiber, low loss, high reliability, and high temperature stability. In addition, since it is a waveguide type optical device, it has a great feature that a plurality of optical functional elements can be easily integrated to realize a higher-performance optical device. Furthermore, optical hybrid integration technology has been developed in which semiconductor elements such as LD and PD are optically coupled to the waveguide on the end face and surface of the substrate, and integrated with semiconductor optical elements with high functionality and high speed. It is also possible to realize a PLC type optical device with higher functionality. Taking advantage of the above-described excellent features, PLC-type high-performance optical devices in which a plurality of optical functional elements are integrated have already been developed. For example, as an example of a thermo-optic optical functional component in which a thermo-optic optical functional element and an optical wavelength filter are integrated, a wavelength channel selector in which a plurality of 2 × 1 optical switches connected in a tree shape and an AWG are integrated Is realized (see, for example, Non-Patent Document 1 below). A schematic configuration of the wavelength channel selector is shown in FIG. In such a thermo-optic optical functional component in which a thermo-optic optical functional element and an optical wavelength filter are integrated, the optical function can be dynamically controlled by changing the power applied to the thermo-optic optical functional element such as TOSW or VOA. it can. In addition, since a PLC type optical wavelength filter or a semiconductor optical element having excellent characteristics is used, a highly functional optical device having excellent characteristics can be realized. Further, a high-performance optical device that is small in size and low in cost can be realized by manufacturing over the same substrate or a single composite substrate obtained by bonding a plurality of component substrates.

Ishii, et al. "PLC type 8-channel wavelength selector" 2002 IEICE Electronics Society Conference Proceedings C-3-65)

  However, thermo-optic optical functional elements such as TOSW and VOA and other optical functional elements such as an optical wavelength filter and a semiconductor optical element are formed on the same substrate or a single composite substrate obtained by joining a plurality of constituent substrates. In the thermo-optic light functional component, when the power applied to the thermo-optic light functional element changes to control the light function, and the amount of heat generated by the power application changes, the heat propagates through the substrate and the thermo-optic light function There is a problem that the temperature of the entire component changes, and the optical characteristics of the optical functional element having temperature dependence on the optical characteristics of the optical wavelength filter, the semiconductor optical element, and the like change.

  Specifically, as described above, the transmission wavelength shifts in the optical wavelength filter, and problems such as fluctuations in the oscillation wavelength, oscillation threshold current, and output power occur in the semiconductor laser. Such characteristic fluctuations degrade the transmission characteristics of the WDM optical communication system. The degree of degradation increases as the channel wavelength interval is narrow, and becomes a serious problem particularly in a high-density WDM (DWDM) optical communication system in which the channel wavelength interval is approximately 200 GHz or less. In addition, in order to accurately match the wavelength characteristics to the specified wavelength grid, even if the temperature control of the thermo-optic functional component is performed using a temperature monitor with a Peltier element, heater, etc., the application to the thermo-optic optical functional component When the change in power is large and the accompanying temperature change exceeds the adjustment capability of the temperature regulator, the temperature control operation cannot follow the actual temperature change, and the temperature of the PLC type optical wavelength filter, semiconductor optical element, etc. There arises a problem that the optical characteristics of the optical functional element having the dependency fluctuate.

  In addition, there is a method of making the PLC-type optical wavelength filter and the semiconductor optical device temperature-independent so that the optical characteristics do not fluctuate even if the temperature changes. However, the manufacturing cost increases and characteristics such as loss deteriorate. Problems arise. Taking AWG temperature independence as an example, a method has been realized in which grooves are formed in the arrayed waveguide portion and filled with silicone resin, but the loss is caused by the diffraction that occurs when light passes through the grooves. Or an additional process such as grooving or filling with a silicone resin raises the problem of increased manufacturing costs. In addition, a thermo-optic optical functional element and an optical functional element having temperature dependence on the optical characteristics are manufactured on different substrates and connected with an optical fiber, or light having temperature dependence on the thermo-optic optical functional element and the optical characteristics. Although it is conceivable to arrange the functional elements apart so as not to cause thermal interference, the circuit size increases, and additional steps such as a step of connecting multiple substrates with optical fibers This causes problems such as an increase in manufacturing cost.

  An object of the present invention is to solve the above-described problems, so that the optical characteristics of the optical functional element are not changed even if the electric power applied to the thermo-optical optical functional element is changed for the control of the optical function. Another object of the present invention is to provide a low-cost and compact thermo-optic optical functional component and its control method.

In order to achieve the above object, the thermo-optic optical functional component according to the first aspect of the present invention applies an electric power to the thin film heater to give a temperature change to the optical waveguide and uses the refractive index change induced by the temperature change to make an optical function. At least one thermo-optic optical functional element that controls the temperature, and at least one optical functional element having temperature dependence in the optical characteristics, and the thermo-optical optical functional element and the optical characteristics. In a thermo-optic optical functional component formed on one composite substrate in which optical functional elements having temperature dependency are bonded to the same substrate or a plurality of component substrates,
In addition to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element, at least one pseudo thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element, the substrate, or the It is formed on a composite substrate.

  The thermo-optic optical functional component of the second invention is the thermo-optic optical functional component of the first invention, wherein the pseudo thin film heater has an optical phase control of the thermo-optic optical functional element for controlling the optical function. Even if the power applied to the thin film heater contributing to the temperature changes, a predetermined power is applied so that the temperature of the optical functional element having temperature dependence on the optical characteristics is substantially constant. It is characterized by that.

  According to a third aspect of the present invention, there is provided the thermo-optic optical functional component according to the first aspect, wherein the thin-film heater contributes to optical phase control of the thermo-optic optical functional element for optical function control. The power is applied so that the sum of the power applied to the pseudo-thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element is constant. It is characterized by.

  According to a fourth aspect of the present invention, there is provided a thermo-optic light functional component according to any one of the first to third inventions, wherein the number of the pseudo thin film heaters is plural.

  The thermo-optic optical functional component of the fifth invention is the thermo-optic optical functional component according to any one of the first to fourth inventions, wherein the heat generated by applying electric power to the pseudo thin film heater is The pseudo thin film heater is disposed at a position that does not affect the optical function of the thermo-optic optical functional element.

  According to a sixth aspect of the present invention, there is provided the thermo-optic optical functional component according to any one of the first to fifth inventions, wherein the thermo-optic optical functional element is a thermo-optic optical switch element. Features.

  According to a seventh aspect of the present invention, there is provided the thermo-optic optical functional component according to any one of the first to fifth inventions, wherein the thermo-optic optical functional element is a thermo-optic variable optical attenuator. It is characterized by.

  According to an eighth aspect of the present invention, there is provided the thermooptic optical functional component according to any one of the first to seventh inventions, wherein the optical functional element having temperature dependence on the optical characteristics is an arrayed waveguide. It is a diffraction grating or an asymmetric Mach-Zehnder interferometer.

  According to a ninth aspect of the present invention, there is provided the thermo-optic optical functional component according to any one of the first to seventh inventions, wherein the optical functional element having temperature dependence on the optical characteristics is a semiconductor laser. It is a waveguide type laser light source hybrid-integrated in a waveguide so that emitted light is optically coupled.

  According to a tenth aspect of the present invention, in the thermooptic optical functional component according to any one of the first to ninth aspects, the substrate is made of silicon, and the material constituting the waveguide is mainly quartz. It is characterized by being a glass material as a component.

In addition, according to the eleventh aspect of the invention, there is provided a method for controlling a thermo-optic optical functional component, wherein electric power is applied to the thin film heater to change the temperature of the optical waveguide, and the optical function is controlled using the refractive index change induced by the temperature change. At least one thermo-optic optical functional element, at least one optical functional element having temperature dependence in optical characteristics, and temperature dependence in the thermo-optic optical functional element and the optical characteristics. Are formed on the same substrate or one composite substrate obtained by bonding a plurality of constituent substrates,
Further, in addition to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element, at least one pseudo thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element, the substrate, or , A method for controlling a thermo-optic optical functional component formed on the composite substrate,
Even if the electric power applied to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element changes in order to control the optical function, the pseudo thin film heater does not change the temperature in the optical characteristics. Predetermined power is applied so that the temperature of the optical functional element having dependency is substantially constant.

The thermo-optic optical functional component control method according to the twelfth aspect of the invention applies power to the thin film heater to change the temperature of the optical waveguide, and controls the optical function using the refractive index change induced by the temperature change. At least one thermo-optic optical functional element, at least one optical functional element having temperature dependence in optical characteristics, and temperature dependence in the thermo-optic optical functional element and the optical characteristics. Are formed on the same substrate or one composite substrate obtained by bonding a plurality of constituent substrates,
Further, in addition to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element, at least one pseudo thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element, the substrate, or , A method for controlling a thermo-optic optical functional component formed on the composite substrate,
The power applied to the thin film heater contributing to the optical phase control of the thermo-optic optical functional element for controlling the optical function, and the pseudo thin film not contributing to the optical phase control of the thermo-optical optical functional element The power is applied so that the sum total with the power applied to the heater is constant.

  Further, the control method of the thermo-optic optical functional component of the thirteenth invention is the sum of electric power applied to the thin film heater and the pseudo thin-film heater in the control method of the thermo-optic optical component of the eleventh invention or the twelfth invention. Is the maximum value of electric power required for controlling the optical function of the thermo-optic optical functional component.

  In the thermo-optic optical functional component of the first invention as described above, temperature is applied to the optical waveguide by applying power to the thin film heater, and the optical function is controlled using the refractive index change induced by the temperature change. At least one thermo-optic optical functional element, and at least one optical functional element having temperature dependence on optical characteristics, and temperature dependence on the thermo-optic optical functional element and the optical characteristics. In a thermo-optic optical functional component formed on the same substrate or a single composite substrate in which a plurality of constituent substrates are joined, the optical functional device having the property contributes to the optical phase control of the thermo-optic optical functional device. In addition to the thin film heater, at least one pseudo thin film heater that does not contribute to optical phase control of the thermo-optic optical functional element is formed on the substrate or the composite substrate. , Free to adjust the power applied to the thin film heater similar, the total power applied to the thermal-optical functional component can be freely adjusted. Therefore, even if the power applied to the thin film heater of the thermo-optic optical functional element changes for the control of the optical function, the power applied to the pseudo thin-film heater is adjusted as appropriate so that the total applied power to the thermo-optic optical functional component As a result, the temperature change of the optical functional element can be suppressed, and as a result, the fluctuation of the optical characteristics of the optical functional element due to the temperature change can be suppressed and a stable thermo-optic optical functional component can be obtained. Can be realized. For example, power is applied to the pseudo thin film heater so that the sum of the power applied to the thin film heater of the thermo-optic optical functional element and the power applied to the pseudo thin film heater is constant for controlling the optical function. In this case, the temperature of the optical functional element can always be kept constant even if the power applied to the thin film heater of the thermo-optic optical functional element changes. Can be reliably prevented.

  According to the thermo-optic optical functional component of the second invention, the pseudo-thin film heater includes a power applied to the thin-film heater that contributes to optical phase control of the thermo-optic optical functional element for controlling the optical function. The optical functional element is configured to be applied with a predetermined power so that the temperature of the optical functional element having temperature dependence in the optical characteristics is substantially constant even if the optical characteristic changes. Therefore, a stable thermo-optic optical functional component can be realized.

  Further, according to the thermo-optic optical functional component of the third invention, the electric power applied to the thin film heater contributing to the optical phase control of the thermo-optic optical functional element for controlling the optical function, and the light of the thermo-optic optical functional element The power applied to the thin film heater of the thermo-optic optical functional element for controlling the optical function because the total sum with the power applied to the pseudo thin film heater that does not contribute to the phase control is constant. Even if the temperature changes, the temperature of the optical functional element can be kept constant at all times, and the fluctuation of the optical characteristics of the optical functional element due to the temperature change can be more reliably prevented to realize a more stable thermo-optic optical functional component be able to.

  Further, according to the thermo-optic optical functional component of the fourth invention, since the number of the pseudo thin film heater is plural, the power applied to the pseudo thin film heater is adjusted to adjust the total applied power to the thermo-optic optical functional component. Since it is possible to reduce the applied power per pseudo thin film heater by distributing to a plurality of pseudo thin film heaters, the pseudo thin film heater is generated by applying power and becomes larger as larger power is applied. It is possible to reduce deterioration over time such as resistance value fluctuation and disconnection.

  According to the thermo-optic optical functional component of the fifth invention, the pseudo-thin film heater is disposed at a position where the heat generated by applying electric power to the pseudo-thin film heater does not affect the optical function of the thermo-optic optical functional element. Therefore, the power to be applied to the pseudo thin film heater can be freely set independently of the optical function control of the thermo-optic light functional component. Easy to determine.

  According to the thermo-optic optical functional component of the sixth invention or the seventh invention, the thermo-optic optical functional element is a thermo-optic optical switch element or a thermo-optic variable optical attenuator. Even if the power applied to the thin film heater of the thermo-optic optical switch element or thermo-optic variable optical attenuator changes to control the variable light attenuation function, the power applied to the pseudo thin film heater is adjusted appropriately to By appropriately adjusting the total applied power to the optical functional component, the temperature change of the optical functional element can be suppressed, and as a result, the fluctuation of the optical characteristics of the optical functional element due to the temperature change can be suppressed. A stable thermo-optic optical functional component can be realized.

  According to the thermo-optic optical functional component of the eighth or ninth invention, the optical functional element is an arrayed waveguide diffraction grating, an asymmetric Mach-Zehnder interferometer, or a waveguide type laser light source. Therefore, even when the power applied to the thin-film heater of the thermo-optic optical component for the control of the optical function changes, the power applied to the pseudo-thin film heater is appropriately adjusted so that the total applied power to the thermo-optic optical functional component The temperature change of the arrayed waveguide grating, the asymmetric Mach-Zehnder interferometer, or the waveguide type laser light source can be suppressed by adjusting appropriately, and as a result, the arrayed waveguide grating or asymmetrical due to the temperature change. Stable thermo-optic functional components can be realized by suppressing fluctuations in the wavelength of the Mach-Zehnder interferometer and fluctuations in the oscillation wavelength of the waveguide laser source. That.

  According to the thermo-optic optical functional component of the tenth invention, since the substrate is made of silicon and the material constituting the waveguide is a glass material mainly composed of quartz, low loss and long-term reliability, optical fiber Thermooptic optical functional parts with excellent connectivity and temperature stability can be realized. Furthermore, since the thermal conductivity of silicon, which is a substrate material, is 100 times larger than that of a glass material mainly composed of quartz, which is a waveguide material, the heat generated by applying power to the thin film heater is directed toward the substrate. The escape and horizontal diffusion of heat can be suppressed, and a local temperature change can be given, so that the thermo-optic optical functional element can be miniaturized and the thermo-optic optical functional component can be miniaturized accordingly.

  In addition, according to the control method of the thermo-optic optical functional component of the eleventh aspect of the invention, the optical function is applied using the refractive index change induced by the temperature change by applying electric power to the thin film heater to change the temperature of the optical waveguide. At least one thermo-optic optical functional element to be controlled, at least one optical functional element having temperature dependence in optical characteristics, and temperature in the thermo-optical optical functional element and the optical characteristics. The thin film heater in which the optical functional element having dependency is formed on the same substrate or a single composite substrate obtained by bonding a plurality of constituent substrates, and further contributes to optical phase control of the thermo-optic optical functional element In addition, there is a method of controlling a thermo-optic optical functional component formed on at least one pseudo thin film heater that does not contribute to optical phase control of the thermo-optic optical functional element, the substrate, or the composite substrate. And said Similar thin film heaters have temperature dependence on the optical characteristics even if the power applied to the thin film heaters that contributes to the optical phase control of the thermo-optic optical functional elements changes for the purpose of controlling optical functions. Since the predetermined power is applied so that the temperature of the optical functional element having the optical characteristics is substantially constant, the fluctuation of the optical characteristics of the optical functional element due to the temperature change can be suppressed, and the thermo-optic light Stabilization of functional parts can be realized.

  According to the control method for a thermo-optic optical functional component of the twelfth aspect of the invention, an optical function is applied using a refractive index change induced by the temperature change by applying electric power to the thin film heater to give a temperature change to the optical waveguide. At least one thermo-optic optical functional element to be controlled, at least one optical functional element having temperature dependence in optical characteristics, and temperature in the thermo-optical optical functional element and the optical characteristics. The thin film heater in which the optical functional element having dependency is formed on the same substrate or a single composite substrate obtained by bonding a plurality of constituent substrates, and further contributes to optical phase control of the thermo-optic optical functional element In addition, there is a method of controlling a thermo-optic optical functional component formed on at least one pseudo thin film heater that does not contribute to optical phase control of the thermo-optic optical functional element, the substrate, or the composite substrate. Light machine For controlling the electric phase applied to the thin film heater contributing to the optical phase control of the thermo-optic optical functional element and the pseudo thin film heater not contributing to the optical phase control of the thermo-optical optical functional element. Since the power is applied so that the sum of the applied power and the applied power is constant, the light is controlled even if the power applied to the thin film heater of the thermo-optic optical functional element is changed for controlling the optical function. The temperature of the functional element can be kept constant at all times, the fluctuation of the optical characteristics of the optical functional element due to temperature change can be prevented more reliably, and the thermo-optic optical functional component can be further stabilized.

  Further, according to the control method of the thermo-optic optical functional component of the thirteenth invention, the total sum of the power applied to the thin film heater and the pseudo thin-film heater is constant and for controlling the optical function of the thermo-optic optical functional component. Since it is characterized by the maximum value of the required power, the total sum of the applied power can be kept to the minimum necessary.

  The above-described thermo-optic optical functional component of the present invention and the control method thereof need to match the transmission wavelength and oscillation wavelength of the optical functional element with the prescribed optical wavelength grid with higher accuracy, and the channel spacing is narrower. The effect is greater as it is applied to a WDM optical functional component used in a WDM optical communication system, and in particular, an optical functional component for a DWDM optical communication system having a channel interval of approximately 200 GHz or less that requires extremely high wavelength accuracy. When applied to, a great effect can be obtained. Furthermore, the above-described thermo-optic optical functional component and the control method thereof according to the present invention have a greater effect when applied to a thermo-optic optical functional component in which the variation in applied power generated for controlling the optical function is larger. For example, when the output channel waveguide from which light is output is switched from the endmost output channel waveguide to the endmost output channel waveguide on the opposite side, a large variation in applied power occurs. 1 × N optical switch with optical switches connected in a tree shape, or multiple 2 × 2 lights that cause large fluctuations in the amount of applied energy when switching from a state where all TOSWs are driven to a state where all TOSWs are not driven When applied to an optical switch array in which switches are arranged in parallel, a great effect can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the following examples, a glass material mainly composed of quartz was used as a waveguide material. However, the present technology is not limited to this, and semiconductor materials, organic dielectric materials, and other inorganic dielectric materials are used. The present invention can also be applied when other waveguide materials such as materials are used, and the effect of wavelength stabilization against fluctuations in the driving state of the thermo-optic optical element can be obtained in the same manner as in this embodiment. The greater the temperature dependence of the waveguide material, the greater the effect. In this embodiment, silicon is used as the substrate. However, the present technology is not limited to this, and a substrate made of another semiconductor material or another inorganic dielectric material such as quartz is used as the substrate material. The above effect can be obtained in the same manner as in this embodiment.
[Example 1]

FIG. 1 shows the configuration of a thermo-optic optical functional component according to the first embodiment of the present invention.
As shown in the figure, this embodiment is a 16 × 1 in which an AWG 8 made of a quartz-based planar lightwave circuit and 15 2 × 1 optical switches 6a to 6o made of a heater loaded MZI are connected in a tree shape. By integrating the optical switch 10 and switching the driving pattern of the 2 × 1 optical switches 6 a to 6 o, an arbitrary one-wave optical signal among 16 WDM optical signals input to the input channel waveguide 31 can be obtained. This is an example in which a wavelength channel selector that outputs to the output channel waveguide 32 is configured.

  In the drawing, the AWG 8 and the 2 × 1 optical switches 6a to 6o are schematically shown, and the detailed structures are as shown in FIGS. 7 and 9, respectively. The design parameters of the AWG 8 are as follows: the channel spacing is 50 GHz, the FSR is 32 ch (1600 GHz), the number of the channel waveguide arrays 36 is 125, the adjacent waveguide length difference (ΔL) of the channel waveguide array 36 is 125 μm, and the slab waveguide 35a. , 35b has a focal length of 9 mm and a 3 dB transmission bandwidth of about 0.2 nm. As the AWG 8, one having 17 inputs and 17 outputs is used. Of the 17 waveguides on the output side, 16 waveguides are connected via channel waveguides 37 (first to sixteenth channel waveguides 37a to 37p). The 16 × 1 optical switch 10 was connected, and the remaining one was connected to the circuit end as a monitor waveguide 38 for characteristic evaluation of the AWG 8 alone.

  The 2 × 1 optical switches 6a to 6o are 3 dB couplers in which the couplers 33a and 33b are configured by directional couplers, the optical path lengths of the arm waveguides 34a and 34b are equal, and the upper part of the upper part of the arm waveguide 34a. A thin film heater 4 is loaded on the clad 2b. In the schematic diagram of the 2 × 1 optical switches 6a to 6o in FIG. 1, as shown in FIG. 9C, the input channel waveguide on the side where the corners are blacked out is 31a, and the input channel waveguide on the opposite side is 31a. 31b, the output channel waveguide is 32b, and when power is not supplied to the thin film heater 4, the input channel waveguide 31a and the output channel waveguide 32b are optically connected to the light propagating through the arm waveguide 34a. When power that gives a phase difference of λ / 2 (hereinafter referred to as switching power) is supplied to the thin film heater 4, the input channel waveguide 31b and the output channel waveguide 32b are optically connected. Note that the switching power of the 2 × 1 optical switches 6a to 6o used in this example is all 0.5W.

  In the present embodiment, specifically, the arm waveguides 34a and 34b are arranged so that the heat generated by the application of electric power to the pseudo thin film heaters 5a to 5d does not affect the optical characteristics of the 2 × 1 optical switches 6a to 6o. In order not to change the optical path length difference between them, the distance between the four pseudo thin film heaters 5a to 5d and the 2 × 1 optical switches 6a to 6o is 200 μm or more, and the 16 × 1 optical switch 10 is configured. The 2 × 1 optical switches 6a to 6o are arranged so as to be close to each stage of the tree structure.

  This example was manufactured using the manufacturing process of the quartz-based planar lightwave circuit shown in FIG. First, the lower clad 2a and the core 3 are formed on the silicon substrate 1 by using a flame deposition method (FHD method). Next, the core 3 is processed into a waveguide pattern shape using a photolithography technique and a dry etching technique. Next, an upper cladding 2b is deposited thereon to form a buried waveguide structure. Further, the thin film heater 4 and the pseudo thin film heater 5 are formed on the upper clad 2b by using a vacuum deposition method, a photolithography method, and a wet etching method. In this embodiment, the thickness of the silicon substrate 1 is 1 mm, the thickness of the lower cladding layer 2a is 20 μm, the thickness of the upper cladding layer 2b is 20 μm, the cross-sectional dimension of the core 3 is 7 μm square, and the core 3 and the cladding 2a, The relative refractive index difference from 2b was 0.7%.

  In order to confirm the effectiveness of the present technology, the wavelength channel selector described above was manufactured, and the wavelength variation of the AWG 8 when the driving state of the 16 × 1 optical switch 10 was changed was measured. The produced wavelength channel selector was fixed to an aluminum mount with heat radiating fins using a heat conductive adhesive, and was installed in a thermostatic bath maintained at 30 ° C. to evaluate optical characteristics. In this embodiment, transmission between the input channel waveguide 31 and the monitor channel waveguide 38 is performed using an ASE (Amplified Spontaneous Emission) light source and an optical spectrum analyzer (OSA) using an EDFA (Erbium Doped Fiber Amplifier). The center wavelength was determined. Further, a variable wavelength light source whose oscillation wavelength is adjusted to the transmission center wavelength between the input channel waveguide 31 and the monitor channel waveguide 38 measured with no power applied is connected to the input channel waveguide 31 and the monitor channel guide is connected. An optical power meter was connected to the waveguide 38, and the light intensity output to the monitoring channel waveguide 38 was measured while changing the driving state of the 16 × 1 optical switch 10. When the driving states for outputting the signal light demultiplexed to the channel waveguides 37a to 37p by the AWG 8 to the output channel waveguide 32 are channels 1 to 16, respectively, the channels are in the order of 1, 16, 2, 16, 1 The driving state of the 2 × 1 optical switches 6a to 6o was changed so as to be switched, and the wavelength fluctuation amount and output light intensity fluctuation amount of the AWG 8 were measured. In the thermo-optic optical functional component according to the present embodiment, the selected channel, the channel waveguide optically connected to the output channel waveguide 32, the drive pattern of the 2 × 1 optical switches 6a to 6o, and the driven 2 Table 1 shows the relationship of the number of × 1 optical switches.

  In the table, a circle indicates that the corresponding 2 × 1 optical switch is driven (switching power is applied). As shown in the table, the number of 2 × 1 optical switches to which power is applied when selecting channels 1, 2, and 16 is 0, 1, and 4, respectively. In this embodiment, 2 × 1 optical switches are used. Since the switching power per unit is 0.5 W, the power applied from the power source to the 16 × 1 optical switch 10 (thin film heater 4) necessary for selecting the channels 1, 2, 16 is 0.0, 0.5 and 2.0 W. In this embodiment, the total applied power to the entire circuit is kept at 2.0 W, which is the maximum applied power necessary for driving the 16 × 1 optical switch 10, in the four pseudo thin film heaters 5 a to 5 d. The power of 0.5, 0.375, and 0.0 W was applied to the selected channels 1, 2, and 16 from the power source.

  A graph of the applied power to the 16 × 1 optical switch 10 and the applied power to the pseudo thin film heaters 5a to 5d is shown in FIG. 2A, and the measurement results of the wavelength fluctuation amount and the output light intensity fluctuation amount are shown in FIG. ), As shown in FIG. In FIG. 9A, the solid line represents the power applied to the 16 × 1 optical switch 10, and the broken line represents the sum of the power applied to the pseudo thin film heaters 5a to 5d. For comparison, a conventional wavelength channel selector that does not form the pseudo thin film heater shown in FIG. 6 was also manufactured and the same measurement was performed. As a result, the measurement result shown in FIG. 3 was obtained. 4A shows the power applied to the 16 × 1 optical switch 10, FIG. 4B shows the measurement result of the wavelength fluctuation amount, and FIG. 3C shows the measurement result of the output light intensity fluctuation amount. . As can be seen from the figure, in the conventional wavelength channel selector, since there is no pseudo thin film heater, the total applied power of the entire circuit cannot be adjusted, and according to the power applied to the 16 × 1 optical switch 10, The temperature of the entire circuit fluctuated, and a maximum wavelength fluctuation of about 0.1 nm and a maximum output light intensity fluctuation of about 3 dB were confirmed. Here, a wavelength variation of 0.1 nm corresponds to a change in the temperature of the AWG 8 of about 10 ° C. On the other hand, in this embodiment, the applied power to the pseudo thin film heaters 5a to 5d is adjusted, and the total applied power to the entire circuit can be kept constant. Therefore, the temperature of the entire circuit does not change. Even when the driving state of the × 1 optical switch 10 was changed, the transmission center wavelength of the AWG 8 did not change, and the fluctuation of the output light intensity associated therewith was not observed.

  Further, in this example, the state of channel 1 is maintained for 2000 hours in a state where no power is applied to the 2 × 1 optical switches 6a to 6o and 0.5 W is applied to each of the pseudo thin film heaters 5a to 5d. The fluctuation amount of the resistance value of the pseudo thin film heater at that time was less than 1%. For comparison, a wavelength channel selector that adjusts the total applied power with one pseudo thin film heater without dividing the pseudo thin film heater is also manufactured, and similarly, the state of channel 1, that is, the 2 × 1 optical switch 6a. Evaluation was also made for a case where the electric power of 2.0 W was applied to one pseudo thin film heater without being applied to ˜6o, and the resistance value of the pseudo thin film heater was about 10%. Met. From this result, by dividing the pseudo thin film heater and reducing the applied power per pseudo thin film heater, it is possible to prevent temporal deterioration such as fluctuations in resistance value and disconnection of the pseudo thin film heater caused by power application. It was confirmed. In addition, since the amount of heat generated by each pseudo thin film heater is reduced by dividing the pseudo thin film heater, the 2 × 1 optical switch necessary for suppressing the influence on the optical characteristics of the 2 × 1 optical switches 6a to 6o. The distance from 6a to 6o could be reduced. Specifically, when divided into four, the calorific value per pseudo thin film heater becomes ¼, and the distance between the pseudo thin film heater and the 2 × 1 optical switches 6a to 6o required when not divided. It was confirmed that the optical characteristics of the 2 × 1 optical switches 6a to 6o were not affected even when the size was reduced to ¼.

  Further, in this example, the amount of wavelength fluctuation was measured when the distance from the AGW 8 was the longest and the power applied to the pseudo thin film heater 5d was intentionally halved. Specifically, for the selected channels 1, 2 and 16, powers of 0.5, 0.375 and 0.0 W are applied to the pseudo thin film heaters 5a to 5c in the same manner as described above, and the pseudo thin film heaters 5d are applied. Measured the amount of wavelength fluctuation when driven by applying a power of 0.25, 0.1875, 0.0W. As a result, the maximum wavelength variation was 0.01 nm, and the output light intensity variation was about 0.03 dB. The total power applied to the 16 × 1 optical switch 10 (thin film heater 4) and the pseudo thin film heaters 5a to 5d is 1.75, 1.875, and 2.0 W for the selected channels 1, 2, and 16, respectively. In addition, the temperature of the AWG 8 fluctuated by about 1.0 ° C. because the total sum of applied power fluctuated by 0.25 W at the maximum. Since the pseudo-thin film heater 5a in which the applied voltage is reduced has a large distance from the AWG 8, the ratio of the wavelength fluctuation (0.01 nm is 0.01 nm with respect to the ratio of the total applied power fluctuation (0.25 W is 1/8 of 2 W)). 1/10) of 0.1 nm was slightly less. The fluctuation amount of the above-mentioned wavelength and light intensity is sufficiently small, and it has been confirmed that the power consumption can be reduced by reducing the applied power to the pseudo thin film heater within the required specification range.

  That is, in order to reliably prevent fluctuations in the optical characteristics (wavelength fluctuations, etc.) of the optical functional element due to temperature changes, the power applied to the thin film heater of the thermo-optic optical functional element and the power applied to the pseudo thin film heater However, the present invention is not necessarily limited to this, and depending on the required specifications, the total applied power to the pseudo thin film heater may be slightly reduced to reduce the pseudo The total sum of the power applied to the thin film heater may vary somewhat, the temperature of the optical functional element may vary somewhat, and the optical function of the optical functional element may vary somewhat. That is, in addition to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element, by providing a pseudo thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element, the power applied to the pseudo thin film heater can be reduced. It is possible to freely adjust the total applied power to the thermo-optic light functional component. In the pseudo thin film heater, even if the electric power applied to the thin film heater of the thermo-optic optical functional element is changed for controlling the optical function, the temperature of the optical functional element is substantially constant (including a constant case). It suffices that predetermined power is applied. Moreover, when reducing the total applied power to the pseudo thin film heater as described above, the applied power of any pseudo thin film heater may be reduced, but the applied power to the pseudo thin film heater having a large distance from the optical functional element. Is more effective because the variation ratio of the optical characteristics of the optical functional element is smaller than the variation ratio of the total applied power to the thermo-optic optical functional component. These also apply to the following examples.

In this embodiment and the following embodiments, an AWG having a channel spacing of 50 GHz is used as the temperature-dependent optical filter. However, the present technology is not limited to this, and the optical characteristics include temperature. As long as the optical functional element has dependency, it can be applied even when an optical functional element having another configuration such as an asymmetric MZI type optical filter is used. The effect of improving the stability is obtained in the same manner as in this example. In this embodiment, an N × 1 optical switch is used as the thermo-optic optical element. However, the present technology is not limited to this, and a variable optical attenuator, a 2 × 2 optical switch array, etc. In the case of a thermo-optic optical functional component in which the electric power applied to the thermo-optic optical functional element changes for function control, the stability of the optical characteristics against fluctuations in the driving state of the thermo-optic optical functional element as in this embodiment In addition, a thermo-optic optical functional component having a larger fluctuation in applied power has a greater effect. Further, in the present embodiment and the following embodiment, the manufacturing process of the above-described quartz-based planar lightwave circuit is used. However, the present technology is not limited to this, and for example, a method for forming a waveguide material Can be applied to the case where a sputtering method, a CVD method, or the like is used, and the case where a wet etching method or an ion milling method is used as a processing method for a waveguide material. It is done.
[Example 2]

FIG. 4 shows a thermo-optic optical functional component according to the second embodiment of the present invention.
As shown in the figure, in this embodiment, a 16 channel array light source 11 composed of 16 semiconductor lasers 9a to 9p oscillating at different wavelengths and 15 2 × 1 optical switches 6a composed of heater loaded MZIs. Among the 16 semiconductor lasers 9a to 9p forming a 16 channel array light source by integrating the 16 × 1 optical switch 10 in which 6o are connected in a tree shape and switching the driving pattern of the 2 × 1 optical switches 6a to 6o This is an example in which a variable wavelength light source that outputs an optical signal output from any one semiconductor laser to the output channel waveguide 32 is configured.

  In this example, the 16-channel array light source 11 was fabricated by mounting 16 single-channel semiconductor lasers 9a to 9p having different oscillation wavelengths in the groove from which the waveguide material was removed. The semiconductor lasers 9a to 9p are DFB (Distributed Feedback) lasers and are mounted using an optical / electric hybrid integration technique so that output light is optically coupled to the channel optical waveguides 37a to 37p. Further, a monitoring semiconductor laser 9q is mounted adjacent to the 16 channel array light source 11 so that the oscillation wavelength can be measured easily and stably. The monitor semiconductor laser 9q was mounted so that the output light was optically coupled to the monitor waveguide 38, and the monitor waveguide 38 was connected to the circuit end. In the present embodiment, the schematic configuration and design parameters of the used 16 × 1 optical switch 10 and the arrangement method of the pseudo thin film heaters 5a to 5d are the same as those in the first embodiment, and thus detailed description thereof is omitted. Further, the structure, dimensions, and manufacturing procedure of the waveguide are the same as those in the first embodiment, and thus detailed description thereof is omitted.

  In order to confirm the effectiveness of the present technology, the variable wavelength light source of the present invention in which the pseudo thin film heaters 5a to 5d are formed and the conventional in which the pseudo thin film heaters 5a to 5d are not formed in this embodiment as well as the first embodiment. A variable wavelength light source was prepared. The produced variable wavelength light source was fixed to an aluminum mount with heat radiating fins using a heat conductive adhesive, and was installed in a thermostatic bath maintained at 30 ° C. to evaluate optical characteristics. In this embodiment, when the driving states for outputting the signal light output from the semiconductor lasers 9a to 9p to the output channel waveguide 32 are channels 1 to 16, respectively, the channels are 1, 16, While changing the driving state of the 2 × 1 optical switches 6a to 6o so as to be switched in the order of 2, 16, 1, the amount of fluctuation in the oscillation wavelength of the output light of the monitoring semiconductor laser 9q output from the monitor waveguide 38 is changed. It was measured. In the present embodiment, the driving method of the 16 × 1 optical switch 10 associated with channel switching and the method of applying power to the pseudo thin film heaters 5a to 5d are the same as in the first embodiment, and thus detailed description thereof is omitted.

  As a result of the measurement, the fluctuation amount of the oscillation wavelength is about 0.1 nm or less with the variable wavelength light source of the present invention in which the pseudo thin film heaters 5a to 5d are formed, and about 1 with the conventional variable wavelength light source without the pseudo thin film heaters 5a to 5d. 0.0 nm. Also in the present embodiment, as in the first embodiment, the conventional variable wavelength light source does not have a pseudo thin film heater, so that the total applied power of the entire circuit cannot be adjusted and applied to the 16 × 1 optical switch 10. The temperature of the entire circuit fluctuates according to the power to be generated, and the oscillation wavelength of the semiconductor laser 9q fluctuates greatly. However, in the variable wavelength light source of the present invention, by adjusting the power applied to the pseudo thin film heaters 5a to 5d, Since the total applied power to the entire circuit was kept constant, the temperature of the entire circuit did not change, and the oscillation wavelength of the semiconductor laser 9q did not change even when the driving state of the 16 × 1 optical switch 10 was changed. Further, from the comparison with the variable wavelength light source, which was prepared for comparison and the total applied power is adjusted by one pseudo thin film heater without dividing the pseudo thin film heater into four, the power application is performed in the same manner as in the first embodiment. The effect of suppressing the deterioration of the pseudo thin film heater over time was confirmed.

In this embodiment, an array light source using a semiconductor laser is used as an optical functional element having temperature dependence in optical characteristics. However, the present technology is not limited to this, and a Bragg grating mirror and a front surface AR (Anti- It can also be applied to the case where other laser elements such as an external cavity type laser using a reflection-coated laser are used, and the optical characteristics with respect to fluctuations in the driving state of the thermo-optic optical functional element as in this embodiment. The effect of improving the stability is obtained.
Example 3

FIG. 5 shows a thermo-optic optical functional component according to the third embodiment of the present invention.
As shown in the figure, in this embodiment, AWG 8 manufactured by a quartz-based planar lightwave circuit and eight VOAs 7a to 7h made of a heater loaded MZI are integrated to adjust the power applied to the VOAs 7a to 7h. Thus, the optical level of the optical signal having the wavelength of eight waves input to the eight input channel waveguides 31a to 31h is adjusted, and the optical level that is wavelength-multiplexed by the AWG 8 and output to the output channel waveguide 32 It is the example which comprised the AWG multiplexer (V-MUX) with an adjustment function.

In FIG. 5, VOAs 7a to 7h are schematically shown, but the detailed structure is as shown in FIG. 9, and the couplers 33a and 33b are 3 dB couplers configured by directional couplers, and arm waveguides 34a, The optical path length of 34b is equal, and the thin film heater 4 is loaded on the upper clad 2b above the arm waveguide 34a. As shown in the schematic diagram of FIG. 9D, the input channel waveguide is 31a, the output channel waveguide is 32b, the power P is applied to the thin film heater 4, and the light intensity is | E ₀ in the input channel waveguide 31a. When | ² light is incident, the light intensity | E ₂ | ² of the light output to the output channel waveguide 32b is expressed by an equation in which (Equation 6) is substituted for Δφ in (Equation 4). Therefore, the amount of light attenuation given by the VOA is 0 dB when P = 0, and ∞ dB when P = (π / 2) / (dφ / dP). In this example, a VOA with a power of 0.5 W that satisfies P = (π / 2) / (dφ / dP), which has an optical attenuation of ∞ dB, was used. Similarly to the first embodiment, the AWG 8 is a 9-input 1-output type, and among the 9 waveguides on the input side, 8 are connected to the VOAs 7a to 7h, and the remaining 1 is the AWG 8 alone. The monitor waveguide 38 for characteristic evaluation was connected to the circuit end. Further, the pseudo thin film heaters 5a to 5h are arranged adjacent to the VOAs 7a to 7h, respectively. In the present embodiment, the schematic structure and setting parameters of the AWG 8 are the same as those in the first embodiment except that they have 9 inputs and 1 output, and thus detailed description thereof is omitted. In this embodiment, the structure, dimensions, and manufacturing procedure of the waveguide are the same as those in the first embodiment, and thus detailed description thereof is omitted.

In order to confirm the effectiveness of the present technology, the V-MUX of the present invention in which the pseudo thin film heaters 5a to 5h are formed and the conventional in which the pseudo thin film heaters 5a to 5h are not formed in this embodiment as well as the first embodiment. V-MUX was prepared, and the prepared V-MUX was fixed to an aluminum mount with a radiation fin using a heat conductive adhesive, and installed in a thermostatic bath maintained at 30 ° C. Optical properties were evaluated. In this embodiment, when all the eight VOAs are driven so that the light attenuation amount becomes ∞ dB, the eight VOAs are all driven so that the light attenuation amount becomes 0 dB. The amount of wavelength variation of AWG8 was measured. Also in this example, similarly to Example 1, the transmission center wavelength between the monitoring channel waveguide 38 and the output channel waveguide 32 was obtained using an ASE light source using EDFA and OSA. All of the VOAs 7a to 7h used in this example are 0.0 W for the optical attenuation amount of 0 dB and 0.5 W for the optical attenuation amount of ∞ dB. The sum of the power applied from the power source to the VOAs 7a to 7h, which is required for the attenuation to be 0 and ∞ dB, is 0.0 W and 4.0 W, respectively. In this embodiment, the power applied to the pair of adjacent VOA and pseudo thin film heater is always the maximum power applied to one VOA, that is, the power to the pseudo thin film heater so as to be kept at 0.5 W. Was applied from a power source. Specifically, when power of P ₁ is applied to the VOA 7a, the thin film heater 5a is driven so that power of P ₂ = 0.5−P ₁ [W] is always applied. Therefore, when all the eight VOAs were driven so that the light attenuation amounts were 0 and ∞ dB, electric powers of 0.5 W and 0.0 W were applied to all of the pseudo thin film heaters 7a to 7h, respectively. As a result, the total applied power of the entire circuit is always kept at 4.0 W, which is the applied power necessary for controlling the VOAs 7a to 7h. As a result of measurement, in the conventional V-MUX, the fluctuation amount of the transmission center wavelength of the AWG 8 was about 0.2 nm. On the other hand, the transmission center wavelength of AWG8 was not observed in the V-MUX of the present invention. Also in the present embodiment, as in the first embodiment, even if the driving state of the VOAs 7a to 7h is changed, the applied power to the pseudo thin film heaters 5a to 5h is adjusted to keep the total applied power to the entire circuit constant. As a result, the temperature of the entire circuit did not change, and the transmission center wavelength was not observed.

  As described above in detail based on the embodiments, the method and the control method of the thermo-optic optical functional component according to the present invention include a thermo-optic optical functional element and an optical functional element having temperature dependence in optical characteristics. When realizing a thermo-optic optical functional component integrated on the same substrate or a single composite substrate in which a plurality of component substrates are joined, the applied power to the thermo-optic optical functional element changes to control the optical function. Even in this case, the fluctuation of the optical characteristics can be kept low by adjusting the power applied to the pseudo thin film heater. In addition, the number of pseudo thin film heaters can be made plural, and the applied power to the pseudo thin film heater for keeping the total applied power constant can be dispersed to suppress the deterioration of the pseudo thin film heater with time. Moreover, since the heat generated by the application of electric power to the pseudo thin film heater does not affect the optical characteristics of the thermo-optic light functional element, the power applied to the thermo-optic light functional element and the pseudo thin film heater can be easily determined. . Further, since it is made of a waveguide made of a quartz glass material formed on a silicon substrate, it is excellent in low loss, long-term reliability, connectivity with an optical fiber, temperature stability, and the like. Therefore, the present invention provides a thermo-optic optical functional component that has stable optical characteristics regardless of the driving state of the thermo-optic element, is small in size, is low in cost, and has low loss and long-term reliability. It is extremely effective for practical use.

It is a top view which shows schematic structure of the thermo-optic optical functional component which concerns on 1st Example of this invention. It is a measurement result of applied electric power, a wavelength fluctuation amount, and an output light intensity fluctuation amount of the thermo-optic optical functional component according to the first embodiment of the present invention. (A) represents the applied power, (b) represents the measurement result of the wavelength variation, (c) represents the measurement result of the output light intensity variation, and the solid line in (a) is a 16 × 1 optical switch. The broken line represents the sum of the power applied to the pseudo thin film heaters 5a to 5d. It is a measurement result of applied power, wavelength fluctuation amount, and output light intensity fluctuation amount of a conventional wavelength channel selector. (A) represents the applied power, (b) represents the measurement result of the wavelength variation, and (c) represents the measurement result of the output light intensity variation. It is a top view which shows schematic structure of the thermo-optic optical functional component which concerns on the 2nd Example of this invention. It is a top view which shows schematic structure of the thermo-optic optical functional component which concerns on the 3rd Example of this invention. It is a top view which shows schematic structure of the conventional wavelength channel selector. It is a top view which shows schematic structure of an array waveguide diffraction grating (AWG). It is a top view which shows schematic structure of an asymmetric Mach-Zehnder interferometer (MZI) type | mold optical wavelength filter. It is a schematic block diagram of a Mach-Zehnder interferometer (MZI) type optical switch and a variable optical attenuator. (A) is a plan view, (b) is a cross-sectional view taken along line AA ′ in (a), (c) is a schematic view when used as a 2 × 1 optical switch element, and (d) is variable light. It is a schematic diagram in the case of using as an attenuator. It is process drawing which shows an example of the manufacturing method of a quartz-type planar lightwave circuit (PLC).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Cladding 2a Lower cladding 2b Upper cladding 3 Core 4 Thin film heater 5 Pseudo thin film heater 5a-5h 1st-8th pseudo thin film heater 6 2 * 1 optical switch 6a-6o 1st-15th 2 * 1 Optical switch 7 Variable optical attenuator (VOA)
7a-7h 1st-8th variable optical attenuator (VOA)
8 Arrayed waveguide diffraction grating (AWG)
DESCRIPTION OF SYMBOLS 9 Semiconductor laser 9a-9q 1st-9th semiconductor laser 9q Monitoring semiconductor laser 10 16 * 1 optical switch 11 16 channel array light source 31 Input channel waveguide 31a-31h 1st-8th input channel waveguide 32 Output Channel waveguides 32a to 32j first to tenth output channel waveguides 33 couplers 33a and 33b first and second couplers 34 arm waveguides 34a and 34b first and second arm waveguides 35 slab waveguides 35a, 35b First and second slab waveguides 36 Channel waveguide array 37 Channel waveguides 37a to 37q First to sixteenth channel waveguides 38 Monitor waveguide

Claims (13)

It comprises at least one thermo-optic optical functional element that applies power to the thin film heater to change the temperature of the optical waveguide, and controls the optical function using the refractive index change induced by the temperature change, and has optical characteristics. And at least one optical functional element having temperature dependence, and the thermo-optical optical functional element and the optical functional element having temperature dependence on the optical characteristics are the same substrate, or a plurality of constituent substrates In a thermo-optic optical functional component formed on one composite substrate joined together,
In addition to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element, at least one pseudo thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element, the substrate, or the A thermo-optic optical functional component formed on a composite substrate.   Even if the electric power applied to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element changes in order to control the optical function, the pseudo thin film heater does not change the temperature in the optical characteristics. 2. The thermo-optic optical functional component according to claim 1, wherein a predetermined power is applied so that the temperature of the optical functional element having dependency is substantially constant.   For the control of the optical function, the electric power applied to the thin film heater contributing to the optical phase control of the thermo-optic optical functional element and the simulation not contributing to the optical phase control of the thermo-optical optical functional element 2. The thermo-optic optical functional component according to claim 1, wherein the power is applied so that a total sum with the power applied to the thin film heater is constant.   The thermo-optic optical functional component according to any one of claims 1 to 3, wherein the number of the pseudo thin film heaters is plural.   The pseudo thin film heater is arranged at a position where heat generated by applying electric power to the pseudo thin film heater does not affect the optical function of the thermo-optic optical functional element. The thermo-optic optical functional component according to any one of claims 1 to 4.   6. The thermo-optic optical functional component according to claim 1, wherein the thermo-optic optical functional element is a thermo-optic optical switch element.   The thermo-optic optical functional component according to any one of claims 1 to 5, wherein the thermo-optic optical functional element is a thermo-optic variable optical attenuator.   8. The optical functional element having temperature dependence in the optical characteristics is an arrayed waveguide diffraction grating or an asymmetric Mach-Zehnder interferometer. Thermo-optic light functional parts.   The optical functional element having temperature dependency in the optical characteristics is a waveguide type laser light source hybrid-integrated in a waveguide so that the emitted light of the semiconductor laser is optically coupled. 8. The thermo-optic optical functional component according to any one of 7 above.   The thermo-optic optical functional component according to any one of claims 1 to 9, wherein the substrate is made of silicon, and a material constituting the waveguide is a glass material mainly composed of quartz. . It comprises at least one thermo-optic optical functional element that applies power to the thin film heater to change the temperature of the optical waveguide, and controls the optical function using the refractive index change induced by the temperature change, and has optical characteristics. And at least one optical functional element having temperature dependence, and the thermo-optical optical functional element and the optical functional element having temperature dependence on the optical characteristics are the same substrate, or a plurality of constituent substrates Formed on one composite substrate joined together,
Further, in addition to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element, at least one pseudo thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element, the substrate, or , A method for controlling a thermo-optic optical functional component formed on the composite substrate,
Even if the electric power applied to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element changes in order to control the optical function, the pseudo thin film heater does not change the temperature in the optical characteristics. A method for controlling a thermo-optic optical functional component, wherein a predetermined power is applied so that the temperature of an optical functional element having dependence is substantially constant. It comprises at least one thermo-optic optical functional element that applies power to the thin film heater to change the temperature of the optical waveguide, and controls the optical function using the refractive index change induced by the temperature change, and has optical characteristics. And at least one optical functional element having temperature dependence, and the thermo-optical optical functional element and the optical functional element having temperature dependence on the optical characteristics are the same substrate, or a plurality of constituent substrates Formed on one composite substrate joined together,
Further, in addition to the thin film heater that contributes to the optical phase control of the thermo-optic optical functional element, at least one pseudo thin film heater that does not contribute to the optical phase control of the thermo-optic optical functional element, the substrate, or , A method for controlling a thermo-optic optical functional component formed on the composite substrate,
The power applied to the thin film heater contributing to the optical phase control of the thermo-optic optical functional element for controlling the optical function, and the pseudo thin film not contributing to the optical phase control of the thermo-optical optical functional element A method for controlling a thermo-optic optical functional component, wherein the power is applied so that a total sum with the power applied to the heater is constant.   The total sum of electric power applied to the thin film heater and the pseudo thin film heater is constant and is set to a maximum value of electric power necessary for controlling an optical function of a thermo-optic optical functional component. Item 13. The method for controlling a thermo-optic optical component according to item 11 or 12.

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