JPH1152156A - Phase type optical waveguide and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical waveguide device provided with a correctly adjusted specific refractive index difference. SOLUTION: In this optical waveguide, clad glass layers 2d, 2u constituting clad are formed on a substrate 3 and plural lines of cores 1a, 1b whose refractive indexes are higher than that of the clads are embedded in the clad glass layers 2d, 2u and the optical waveguide has at least one input port and one output port. In this case, the phase of a light propergating in between the core and the clad is adjusted by changing the refractive index of the core or the clad while irradiating at least one line of the core 1a or the peripheral clad of the core 1a with X-rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase-type optical waveguide whose phase is accurately adjusted and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the development of optical fiber communication, network complexity and multiplexing of signal wavelengths have been advanced, and the system configuration has been advanced. In such an optical fiber communication system, the importance of an optical circuit element is increasing.

[0003] As one of the general constitutions of the optical circuit element, the optical waveguide device has advantages such as small size, small insertion loss, and easy connection with an optical fiber. As an example of such an optical waveguide device, an arrayed waveguide grating is known (for example, “a channel spacing of 10 GHz arrayed waveguide grating”: 1996 IEICE Electronics Society Conference, C-16).
2).

As shown in FIG. 12, the arrayed waveguide grating 60 has 16 input / output waveguides 62a, 62b,
It is composed of one slab waveguide 63 and 64 array waveguides 64. A phase adjusting film 65 made of an amorphous-silicon film is loaded on each array waveguide so that the phase can be controlled independently. The width of the phase adjustment film 65 is set to 95 μm so that the amount of phase change in each of the TE and TM modes is substantially equal. The phase of light propagating through each array waveguide 64 is adjusted by trimming the phase adjustment film 65 so that the difference in value between adjacent array waveguides is constant.

[0005]

In such an arrayed waveguide grating, it is necessary to strictly control the phase of light determined by the refractive index and the optical path length of the waveguide. If the refractive index or the optical path length of the waveguide deviates from the set values, desired characteristics cannot be obtained, resulting in a defective product, or complicated measures such as trimming of the phase adjustment film must be performed.

An object of the present invention is to solve such a problem and to provide a phase-type optical waveguide whose phase is accurately adjusted and a method of manufacturing the same.

[0007]

In the phase type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, and a plurality of cores having a higher refractive index than the clad are embedded in the clad glass layer. In the phase-type optical waveguide having at least one input port and one output port, the core or the clad is irradiated with X-rays by irradiating at least one core or a clad around the core among a plurality of cores. The phase of light propagating between the core and the clad is adjusted by changing the refractive index.

It is very difficult to form a plurality of optical waveguides having a desired phase amount by depositing glass on a substrate, and it is necessary to correct the phase amount after fabrication. Conventionally, however, it was difficult to form a complicated phase-type optical waveguide because there was no simple adjustment method. According to the phase-type optical waveguide of the present invention, at least one core or the clad around the core among the plurality of optical waveguides formed on the substrate is irradiated with X-rays to change the refractive index of the core or the clad. In other words, the phase of light propagating between the core and the clad is adjusted to a desired value.

When the relative refractive index difference between the core and the clad of the optical waveguide changes, the phase constant of the light propagating through the optical waveguide changes, so that the optical path length of the light or the characteristics of the optical circuit formed by the optical waveguide changes. I do. The method of changing the refractive index can be carried out by irradiating ultraviolet rays, but it is preferable to use X-rays with few restrictions on dopants added to the core.

The method for manufacturing a phase-type optical waveguide according to the present invention comprises forming a clad glass layer to be a clad on a substrate, embedding a plurality of cores having a higher refractive index than the clad in the clad glass layer, A first step of forming a phase-type optical waveguide having one input port and one output port, and irradiating at least one core of the optical waveguide or a clad around the core with X-rays while monitoring characteristics of the optical waveguide. And changing the refractive index of the core or the clad to adjust the phase of light propagating between the core and the clad.

According to the method of manufacturing a phase-type optical waveguide according to the present invention, the core or the clad is irradiated with X-rays while monitoring the characteristics of the optical waveguide, so that an optical waveguide having a desired phase amount can be formed accurately. be able to. By employing this method, it is possible to easily adjust even if a large number of cores are arranged close to each other.

In the phase-type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, and two cores having a higher refractive index than the clad are embedded in the clad glass layer. Has a coupling part in the middle, and one end of the two cores is connected to at least one input port, and the other end is a phase type optical waveguide connected to two output ports. X-rays are applied to at least one core or the clad around the core to change the refractive index of the core or the clad, thereby adjusting the phase of light propagating between the core and the clad. It is characterized by.

According to the phase type optical waveguide of the present invention, a coupling portion is provided between the two cores, one end of the two cores is connected to at least one input port, and the other end is connected to the other end. A directional coupler connected to two output ports is formed on a substrate, and at least one core or a clad around the core in the coupling portion is irradiated with X-rays to change the refractive index of the core or the clad. In other words, the phase of light propagating between the core and the clad is adjusted to a desired value. When the relative refractive index difference between the core and the clad of the optical waveguide at the coupling portion changes, the phase constant of the optical waveguide changes,
Since the coupling length changes, the ratio output to the two output ports can be changed.

According to the method of manufacturing a phase type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, and a clad glass layer having a higher refractive index than the clad is formed in the clad glass layer.
Two cores are embedded, the two cores have an intermediate connection and one end of the two cores is connected to at least one input port and the other end is connected to two output ports A first step of forming a phase-type optical waveguide; and a step of inputting light from one input port of the phase-type optical waveguide and monitoring the power of output light from two output ports, while monitoring the power of the output light from the two output ports. Irradiating at least one core or the clad around the core with X-rays to change the refractive index of the core or the clad, and adjusting the phase of light propagating between the core and the clad. It is characterized by the following. The manufacturing method of the present invention has a coupling portion between two cores, and one end of each of the two cores is connected to at least one input port, and the other end is connected to two output ports. This is a manufacturing method that replaces the directional coupler.
While monitoring the power of the output light from the two output ports, at least one of the two cores in the coupling portion or the cladding around the core is irradiated with X-rays, so that the phase amount is accurately adjusted and output. Light can be distributed in a desired ratio.

In the phase-type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, and two cores having a higher refractive index than the clad are embedded in the clad glass layer. Has two coupling portions and one end of each of the two cores is connected to at least one input port, and the other end is connected to two coupling portions in a phase-type optical waveguide connected to two output ports. X-rays are applied to at least one core or the cladding around the core in the middle of the part to change the refractive index of the core or the cladding, so that the phase of light propagating between the core and the cladding is adjusted. It is characterized by.

According to the phase type optical waveguide of the present invention, the two cores have coupling portions at two places, one end of each of the two cores is connected to at least one input port, and the other end is connected to at least one input port. A Mach-Zehnder interferometer connected to two output ports is formed on a substrate, and at least one core or a clad around the core in the middle of two coupling portions is irradiated with X-rays to form a core or a core. By changing the refractive index of the clad, the phase of light propagating between the core and the clad is adjusted to a desired value. The light input from one input port is divided into two by the first coupling unit, and the two divided lights are input to the second coupling unit. The ratio can be changed arbitrarily.

According to a method of manufacturing a phase-type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, and a clad glass layer having a higher refractive index than the clad is formed in the clad glass layer.
Two cores are embedded, the two cores have a coupling portion at two places, and one end of the two cores is connected to at least one input port, and the other end is connected to two output ports. A first step of forming a phase-type optical waveguide, and inputting light from one input port of the phase-type optical waveguide, and monitoring at least output power of two output ports, at least in the middle of the two coupling portions. A second step of irradiating one core or a clad around the core with X-rays to change the refractive index of the core or the clad and adjusting the phase of light propagating between the core and the clad. It is characterized by.

According to the manufacturing method of the present invention, the two cores have coupling portions at two places, one end of each of the two cores is connected to at least one input port, and the other end is connected to two output ports. Is a manufacturing method related to a Mach-Zehnder interferometer connected to at least one of two cores in a coupling portion or a cladding around the core while monitoring the power of output light from two output ports. Therefore, the output light can be distributed to a desired ratio by accurately adjusting the phase amount.

In the phase type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, a plurality of cores having a higher refractive index than the clad are buried in the clad glass layer, and a plurality of cores are formed. One end of the core is connected to at least one input port via a slab waveguide, and the other end is connected to at least two output ports via a slab waveguide. Among them, at least one core or the clad around the core is irradiated with X-rays to change the refractive index of the core or the clad, and that the phase of light propagating between the core and the clad is adjusted. Features.

According to the phase type optical waveguide of the present invention, one end of each of the plurality of cores is at least one end via the slab waveguide.
An arrayed waveguide grating connected to one input port and the other end connected to at least two output ports via a slab waveguide is formed on the substrate, and at least one of the plurality of cores is provided. The core or the clad around the core is irradiated with X-rays to change the refractive index of the core or the clad, thereby adjusting the phase of light propagating between the core and the clad to a desired value. By applying this to each core or clad, the phase of each core can be easily made uniform.

According to a method of manufacturing a phase-type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, and a plurality of cores having a higher refractive index than the clad are embedded in the clad glass layer. One end of the core is connected to at least one input port via a slab waveguide, and the other end forms a phase-type optical waveguide connected to at least two output ports via a slab waveguide. One step, inputting light from one input port of the phase-type optical waveguide, and irradiating at least one core of the optical waveguide or a clad around the core with X-rays while monitoring the output power of the output port. Or a second step of changing the refractive index of the clad to adjust the phase of light propagating between the core and the clad.

According to the manufacturing method of the present invention, one end of each of the plurality of cores is connected to at least one input port via a slab waveguide, and the other end is connected to at least two output ports via a slab waveguide. This is a manufacturing method related to the connected arrayed waveguide grating. At least one core of the optical waveguide or the clad around the core is irradiated with X-rays while monitoring the output power of the output port. Can be formed uniformly.

In the phase-type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, one core having a higher refractive index than the clad is embedded in the clad glass layer, and one clad. The core has one input port and one output port, and is provided with a gap between the core and an intermediate portion of the core, and a ring-shaped core is optically coupled to the single core and arranged. In an optical waveguide, X-rays are applied to a ring-shaped core or a clad around the core to change the refractive index of the core or the clad, and light that propagates and resonates between the ring-shaped core and the clad around the core is resonated. The phase is adjusted.

According to the phase-type optical waveguide of the present invention, one core has one input port and one output port, and a ring-shaped core is provided by providing a gap with the core at an intermediate portion of the core. Is formed on a substrate, and a ring resonator optically coupled to a single core is formed on a substrate. The ring-shaped core or a clad around the core is irradiated with X-rays to refract the core or the clad. By changing the ratio, the phase of the light that propagates between the ring-shaped core and the clad around the core and resonates can be adjusted, and the resonance wavelength can be adjusted.

In the method for manufacturing a phase-type optical waveguide according to the present invention, a clad glass layer to be a clad is formed on a substrate, and a clad glass layer having a higher refractive index than the clad is formed in the clad glass layer.
In addition to embedding the core, one core has one input port and one output port, and a ring-shaped core is optically connected to the single core by providing a gap with the core at an intermediate portion of the core. Forming a phase-type optical waveguide disposed in combination with the first
Process, input light from the input port of the phase-type optical waveguide,
While monitoring the output power of the output port, the ring-shaped core or the clad around the core is irradiated with X-rays to change the refractive index of the core or the clad, and the gap between the ring-shaped core and the clad around the core is changed. A second step of adjusting the phase of light that propagates and resonates.

According to the manufacturing method of the present invention, one core has one input port and one output port, and a ring-shaped core is formed by providing a gap with the core at an intermediate portion of the core. This method involves a ring resonator that is optically coupled to the core and irradiates the ring-shaped core or the cladding around the core with X-rays while monitoring the output power of the output port. The resonance wavelength can be changed by adjusting the amount.

[0027]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

(Embodiment 1) FIG. 1 is a view showing a configuration of a phase-type optical waveguide according to the present embodiment. FIG. 1 (a) is a plan view of the phase-type optical waveguide, and FIG. It is a side view. In FIG. 1, on a substrate 3, a lower clad glass layer 2d mainly composed of quartz serving as a clad and an upper clad glass layer 2u are formed.
Two cores 1a and 1b having a higher refractive index than the cladding glass are embedded in 2u, and light input ports 4a and 4b and output ports 4c and 4d are provided at both ends.

Next, when one core 1a is irradiated with X-rays, the refractive index changes and two types of phase-type optical waveguides having different characteristics are formed.

In these two systems of phase type optical waveguides, the cladding glass layers 2d and 2u are common, but the two cores 1a and 1u are used.
Since the refractive index of b is different, the phase constants of light propagating through these optical waveguides are different. Since the phase constant is related to the speed of light propagating through the optical waveguide, the optical path length will be different. When the two cores 1a and 1b are optically coupled, the coupling state changes and the ratio of the power output to the output ports 4c and 4d changes.

The method of changing the refractive index of the core can be carried out by irradiating ultraviolet rays. However, it is preferable to use X-rays with few restrictions on the dopants added to the core. In addition, since the refractive index tends to be proportional to the amount of X-ray irradiation, continuous adjustment is possible and accurate adjustment is possible. By employing this method, it is possible to easily adjust an optical waveguide in which a large number of cores are arranged close to each other.

FIG. 2 is a diagram showing the configuration of another phase-type optical waveguide according to the present embodiment. FIG. 2 (a) is a plan view of the phase-type optical waveguide, and FIG. 2 (b) is a side view thereof. is there. In FIG. 2, a lower clad glass layer 2d mainly composed of quartz serving as a clad and an upper clad glass layer 2u are formed on a substrate 3, and the clad glass layers 2d and 2u have a refractive index higher than that of the clad glass. Cores 1a, 1
b are buried, and light input ports 4 are provided at both ends.
a, 4b and output ports 4c, 4d. Next, when the clad 2b around one of the cores 1b is irradiated with X-rays, the relative refractive index difference between the core 1b and the clad 2b is smaller than the relative refractive index difference between the core 1a and the clad 2d, 2u. An optical waveguide is formed.

FIG. 1 shows two types of optical waveguides having different phase characteristics by changing the refractive index of the core 1a, and FIG. 2 shows changing the refractive index of the cladding 2b around the core 1b. Show.

When an optical waveguide having two cores is formed while depositing glass on a substrate, there is a limit to the accuracy of the obtained refractive index. Therefore, the higher the required refractive index is, the more difficult it is to manufacture. In such a case, when one core or the clad around the core is irradiated with X-rays, the refractive index tends to change in proportion to the amount of X-ray irradiation. An optical waveguide device that is equal to or different from the relative refractive index difference between the core and the clad by a desired amount can be easily formed.

The various optical waveguide devices described above have two
Although the case where three cores are arranged has been described, the same effect can be obtained with an optical waveguide device in which three or more cores are arranged.

Next, a method of manufacturing the optical waveguide device according to the present embodiment will be described with reference to FIGS. FIG. 3 is a cross-sectional view for explaining the first step in this manufacturing method, and shows an example of a method of forming a core and a clad having a substantially uniform refractive index on a substrate.

In FIG. 3A, a silica glass substrate 1
Core layer 1 of silica glass doped with germanium on 1
2 are formed. The core layer 12 is obtained, for example, by depositing glass fine particles generated by flame hydrolysis of silicon tetrachloride and germanium tetrachloride, and heating the fine particle layer to a high temperature to convert it to a transparent glass layer.

In FIG. 3B, 2
Resist patterns 13a and 13b having patterns corresponding to the optical waveguides are formed using photolithography.

In FIG. 3C, the resist pattern 1
The core layer 12 is etched using reactive ion etching with the masks 3a and 13b as masks, and core ridges 12a and 12b corresponding to the optical waveguide pattern are formed.

In FIG. 3D, silica glass fine particles formed by a flame hydrolysis method are deposited so as to cover the core ridges 12a and 12b having a pattern corresponding to the optical waveguide, and an upper clad layer 14 is formed. . As a result, an optical circuit having a core and a clad having a uniform refractive index is completed.

Next, the second method of the manufacturing method according to this embodiment will be described.
The steps will be described. At present, it is known that the refractive index of silica glass is efficiently increased by irradiating X-rays having a wavelength of 1.2 to 7.0 angstroms (for example, JP-A-8-169731). FIG. 4 is a graph showing the relationship between the X-ray irradiation amount and the refractive index change amount. That is, the horizontal axis represents the irradiation amount (mA · h), and the vertical axis represents the refractive index change amount (Δn). A mark indicates a change in the refractive index of silica glass to which Ge was added, and a mark indicates a change in the refractive index of high-purity silica glass. Here, mA · h represents the product of the accumulated current in the X-ray generator and the irradiation time.

From the graph of FIG. 4, it can be seen that the refractive index of silica glass to which Ge is added changes more efficiently than that of high-purity silica glass. Further, it can be seen that in both the silica glass to which Ge is added and the high-purity silica glass, the change amount Δn of the refractive index is proportional to the n-th power of the X-ray irradiation amount (0 <n <1). Therefore,
By using the results of FIG. 4, it is possible to set the irradiation amount necessary to obtain a desired refractive index change amount Δn in the silica glass.

FIG. 5 is a cross-sectional view in which the optical waveguide formed in the first step is irradiated with X-rays to form a refractive index distribution.

Referring to FIG. 5, a synchrotron radiation light generator (not shown) has a wavelength of 0.12 nm to 0.7 nm.
X-ray is emitted, and the optical waveguide device 30 formed by the above-described first step through the X-ray intensity modulation mask 31
Is irradiated. The X-ray mask 31 includes a support film 31a that transmits X-rays, and an X-ray shield layer 31b formed thereon by patterning so as to cover a portion other than the one core 12b of the optical waveguide.

The synchrotron radiation (SR light) is transmitted from the synchrotron radiation device through the SR light introducing pipe 33 to the S
It is led into the R light irradiation chamber 32. Since the irradiation chamber 32 contains helium at atmospheric pressure, the synchrotron radiation device side of the introduction tube 33 is maintained in an ultra-high vacuum.
A diaphragm 34 is provided in the introduction pipe 33.

The X-ray intensity modulation mask 31 has an X-ray shield layer 31b formed by patterning so as to cover a portion other than one of the core and a support film 31a that transmits X-rays.
Is provided. For the support film 31a, silicon nitride, silicon carbide, diamond, or the like having mechanical strength and X-ray transmissivity is used. As the X-ray shield layer 31b, a tungsten layer, a tantalum layer, or the like having an X-ray shielding ability is used.

By irradiating the core of the optical waveguide with X-rays through such an X-ray mask 31, the refractive index of the core increases in accordance with the pattern. As a result, the refractive index of one core of the optical waveguide can be formed higher than the refractive index of the other core.

Here, the case where the core portion of the optical waveguide is irradiated with X-rays to form a refractive index distribution has been described. However, the cladding around one of the cores is irradiated with X-rays, and the refractive index distribution is applied to the clad. May be formed.

When the cores 1a and 1b are embedded in the claddings 2u and 2d as shown in FIG. 1, when the cores 1a and 1b are irradiated with X-rays, the cladding 2u above the cores 1a and 1b is also irradiated. Irradiated. As shown in FIG. 4, the refractive index of silica glass to which Ge is added is larger than that of high-purity silica glass, so that the refractive index of the core can be substantially increased. As shown in FIG. 2, when X-rays are irradiated on the claddings 2b on both sides of the core 1b, the claddings 2b on the left and right sides of the core 1b increase in refractive index, but the claddings 2u and 2d on the upper or lower part of the core 1b. Does not change. However, since the refractive indices of the claddings 2b on the left and right sides of the core 1b are large, the refractive index of the peripheral cladding with respect to the refractive index of the core 1b substantially increases, and the relative refractive index difference of the peripheral cladding with respect to the core 1b changes. .

Next, the third method of the manufacturing method according to this embodiment will be described.
The steps will be described. The third step includes the first step and the second step.
This is a step of measuring characteristics of the optical waveguide formed in the step. As described above, the characteristics of the optical waveguide related to the relative refractive index difference include the propagation constant of light propagating through the optical waveguide and the shape of the propagation mode at that time. Since the propagation constant is related to the phase of light propagating through the optical waveguide, there is a method of measuring the phase of light using a low coherent interferometer and Fourier spectroscopy.

Since the propagation mode relates to the spread of the energy propagating through the optical waveguide, when the two cores are optically coupled, the coupling state changes if the shapes of the propagation modes are different. Therefore, the light emitted from the light source is incident on one of the optical waveguides, and the emitted light is received to measure the coupling characteristics. The measuring method is appropriately selected according to the optical circuit formed as described above.

The manufacturing method according to the present embodiment is a method in which the third step of measuring the characteristics of the optical waveguide and the second step of irradiating the core or the clad with X-rays are performed simultaneously.
Since the core or the clad is irradiated with X-rays while measuring the characteristics of the optical waveguide, an optical waveguide having a desired refractive index difference can be accurately formed. (Embodiment 2) Here, a phase type optical waveguide using a directional coupler will be described. FIG. 6 is a plan view showing a phase-type optical waveguide in which a directional coupler is formed on a substrate,
In the directional coupler 40, clad glass layers 2d and 2u to be clad are formed on a substrate 41, and two cores 1a and 1b having a higher refractive index than the clad are embedded in the clad glass layers 2d and 2u. Input ports 42a and 42b and output ports 42c and 4c are provided at both ends of the cores 1a and 1b, respectively.
2d, and a coupling portion C is provided between the cores 1a and 1b. The directional coupler 40 includes an input port 42a,
It has a function of equally dividing the optical power input from either one of the two output ports 42b into the two output ports 42c and 42d.

The distribution ratio has the following relationship. In FIG. 7, the propagation constants of the waveguide modes in the two waveguides are equal, and 0 ≦ z ≦ L is the coupling region. In this coupling region, even and odd symmetric modes exist as normal modes orthogonal to each other, and the respective propagation constants are β _e and β _o . When light is input from the waveguide 1 at the input end z = 0, even / odd symmetric modes having the same electric field amplitude at this point are excited in phase. As these modes propagate through the coupling region, 2
A phase difference (β _e −β _o ) z occurs between the two modes. The propagation distance L at which the phase difference becomes π is L = π / (β _e −β _o ). Since the combined electric field distribution of the even / odd symmetric mode at z = L matches the electric field distribution of the waveguide mode in the waveguide 2 at z> L, all the optical power in the coupling region is guided from the waveguide 1. 100% transition to wave path 2. Therefore, assuming that the coupling length is L / 2, two output ports each have 50
% Power is equally distributed. (Distribution can be performed at a desired ratio by changing the coupling length.) Next, a method for manufacturing a directional coupler will be described. By the manufacturing method described in the first embodiment, the silica glass layers 2d and 2u are formed on the substrate 41, and the two cores 1a and 1b obtained by adding germanium to silica glass are embedded therein. A directional coupler 4 is provided between the cores 1a and 1b.
0 is formed.

The cross-sectional dimension of the core 4 is 8 μm × 8 μm, and the relative refractive index difference Δn ₁ between the core and the clad is 0.4%. At this time, light having a wavelength of 1.55 μm was incident from one input port 42a of the directional coupler 40, and the power of the two output ports 42c and 42d was measured. .

Therefore, the X-ray irradiator shown in FIG. 5 was used to irradiate one core 1a of the joint C with X-rays, and at the same time, the power of the output ports 42c and 42d was measured. As a result, the phase difference between the even and odd symmetric modes changes, and the core 1
Since the amount of coupling to b changed, the power level at the output end could be equalized. Core 1b instead of core 1a
The same effect can be obtained by irradiating the X-rays to the cladding around the. Conventionally, if this difference does not fall within the specified range, it is treated as a defective product, but it can be easily corrected.

(Embodiment 3) Here, a phase type optical waveguide using a Mach-Zehnder interferometer will be described. FIG.
FIG. 2 is a plan view showing a phase type optical waveguide in which a Mach-Zehnder interferometer is formed on a substrate.
0 indicates that the clad glass layers 2d, 2u to be clad are formed on the substrate 51, and the clad glass layers 2d, 2u
Two cores 1a and 1b having a higher refractive index than the cladding are embedded therein. Both ends of the cores 1a and 1b have input ports 52a and 52b and output ports 52c and 52d, respectively, and two connecting portions C ₁ and C ₂ are provided between the cores 1a and 1b. A directional coupler is formed.

The Mach-Zehnder interferometer 50 has a function of distributing the optical power input from one of the input ports 52a and 52b to two output ports 52c and 52d. The distribution can be adjusted by adjusting the optical path difference between the two directional couplers 53a and 53b.
By providing a thermal phase shifter or the like, it can function as a switch.

Conventionally, these two directional couplers 53a, 53a,
In order to adjust the optical path difference between the layers 3b, a method of providing an amorphous-silicon film formed by a sputtering method on the waveguide and applying a compressive residual stress to the waveguide has been performed (for example, “laser trimming”). Phase Control of Optical Waveguide Circuits "(1989 IEICE National Convention: C-2)
62)). In this method, the structure for adjusting the optical path difference is complicated, and fine adjustment is difficult. Thus, the present embodiment provides a precisely adjusted Mach-Zehnder interferometer and its method.

Next, a method of manufacturing the Mach-Zehnder interferometer shown in FIG. 8 will be described. The silica glass layers 2d and 2u are formed on the substrate 51 by the manufacturing method described in the first embodiment.
And germanium added to silica glass therein.
The cores 1a and 1b of the book are formed so as to be embedded. Core 1
The two directional couplers 53a and 53b are located between a and 1b.
Is formed. The cross-sectional dimension of the core 4 is 8 μm × 8 μm, and the relative refractive index difference Δn ₁ between the core and the clad is 0.3%. Next, a wavelength of 1.3 μm is input from one input port 52a.
m, and the power of the two output ports 52c and 52d was measured. Most of the power was output to the output port 52d, but some power was also output to the output port 52c.

Therefore, the X-ray irradiator shown in FIG. 5 was used to irradiate the clad around the core 1a between the two coupling portions with X-rays, and at the same time, the power at the output terminals 52c and 52d was measured. As a result, the phase propagating through the core 1a changes and is not output to the output port 52c, but all outputs
Appeared in 2d. The same effect can be obtained by irradiating the core 1b with X-rays instead of the cladding around the core 1a.

(Embodiment 4) Here, a phase-type optical waveguide using an arrayed waveguide grating will be described. FIG. 9 is a plan view showing a phase-type optical waveguide in which an arrayed waveguide grating is formed on a substrate. Light input from an input waveguide 62a has a distribution broadened by a slab waveguide 63a. Is input to the array waveguide 64. Since the optical path lengths of the adjacent arrayed waveguides 64 are different by a fixed amount, when the light reaches the slab waveguide 63b on the emission side, the wavefront (equiphase plane) is inclined. Further, since the inclination of the wavefront varies depending on the wavelength, light is output to the output waveguide 62b which varies depending on the wavelength.

In the conventional method of adjusting the phase of the array waveguide grating, as shown in FIG. 12, a phase adjustment film 65 is provided on the array waveguide 64, and the phase adjustment film 66 is trimmed. . In this method, the configuration for adjusting the phase is complicated, and fine adjustment is difficult. Therefore, the present embodiment provides an arrayed waveguide grating whose phase has been accurately adjusted and a method thereof.

Next, a method of manufacturing the arrayed waveguide grating shown in FIG. 9 will be described. According to the manufacturing method described in Embodiment 1, a silica glass layer is formed on a substrate, and input / output waveguides 62a and 62b each including a core obtained by adding germanium to silica glass therein, and 64 array waveguides 64 are formed. Two slab waveguides 63a and 63b are arranged between them. The cross-sectional dimension of the core is 4 μm × 4 μm,
The relative refractive index difference Δn ₁ between the core and the clad is 1.0%.

The arrayed waveguide grating 60 thus manufactured
, The phase of light propagating through each array waveguide 64 is measured using a low coherent interferometer and Fourier spectroscopy,
The core of each arrayed waveguide 64 was sequentially irradiated with X-rays using the X-ray irradiation apparatus shown in FIG. 5 so that the value became constant. As a result, the phase difference between adjacent array waveguides could be made constant.

(Embodiment 5) Here, a phase type optical waveguide using a ring resonator will be described. FIGS. 10A and 10B are a plan view (FIG. 10A) and a side view (FIG. 10B) showing a phase type optical waveguide in which a ring resonator is formed on a substrate. cladding glass layer 2d to be a cladding above, 2u are formed, together with one core 1 _S of the high refractive index than the cladding in the cladding glass layer is buried, the core 1 _S one input port 72
It has a one output port 72b, and the core 1 _S and the gap G of the core 1 a ring-shaped provided _R are arranged optically coupled to the core 1 _S in the middle portion of the core 1 _S .

This ring resonator 70 has an input port 72
The light input from a propagates through the core 1 _S to output port 72.
When reaching b, some power is combined with the ring core 1 _R and loss occurs. The transmission characteristic at this time has a steep wavelength dependence as shown in FIG. 11, so that it can be used as a wavelength filter. It is extremely difficult to adjust the resonance wavelength of the ring resonator 70 having such a steep wavelength dependence and to form a filter that blocks a desired wavelength. Characteristics of a single tap ring resonator "(1991 IEICE Spring National Convention: C-244), etc.

Next, a method of manufacturing the ring resonator 70 shown in FIG. 10 will be described. According to the manufacturing method described in the first embodiment, the silica glass layers 2d and 2u
Part 1 of the cores 1 _S and a ring-shaped core 1 _R of the addition of germanium to silica glass in the form embedded by close enough to optically couple. The cross-sectional dimensions of the core 1 _S and the ring core 1 _R are 7 μm × 7 μm, and the relative refractive index difference Δn ₁ between the core and the clad is 0.3%. At this time,
Light having a wavelength of 1.55 μm was incident from one input port 72a constituting the ring resonator, and the power of the output port 72b was measured. As shown in FIG. 11, a sharp wavelength rejection filter characteristic was obtained.

Then, the ring core 1 _R is irradiated with X-rays by using the X-ray irradiator shown in FIG. 5 to increase the refractive index of the ring core 1 _R and adjust the optical path length of the ring, and at the same time, the output port 72 b Output power wavelength characteristics were measured. As a result, the resonance wavelength could be changed to the shorter wavelength side. X on the cladding around the core instead of the ring core
Irradiation with a line can shift to a longer wavelength side.

[0069]

According to the phase type optical waveguide of the present invention, at least one of the cores formed on the substrate or the clad around the core is irradiated with X-rays to change the refractive index of the core or the clad. Therefore, an optical waveguide having an accurate phase constant can be obtained. In the method for manufacturing a phase-type optical waveguide according to the present invention, the core or the clad is irradiated with X-rays while monitoring the characteristics of the optical waveguide, so that an optical waveguide having a desired phase amount can be formed accurately.

[Brief description of the drawings]

FIG. 1 is a plan view (FIG. 1A) and a side view (FIG. 1B) showing the configuration of an optical waveguide device according to the present embodiment.

FIG. 2 is a plan view (FIG. 2A) and a side view (FIG. 2B) showing another configuration of the optical waveguide device according to the present embodiment.

FIG. 3 is a cross-sectional view for explaining the method for manufacturing the optical waveguide device according to the embodiment.

FIG. 4 is a graph showing a relationship between an X-ray irradiation amount and a refractive index change amount.

FIG. 5 is a cross-sectional view illustrating a configuration of an X-ray irradiation device.

FIGS. 6A and 6B are a plan view (FIG. 6A) and a side view (FIG. 6B) showing a configuration of a phase-type optical waveguide having a directional coupler.

FIG. 7 is a diagram illustrating a function of a directional coupler.

FIG. 8 is a plan view (FIG. 8A) and a side view (FIG. 8) showing the configuration of a phase-type optical waveguide including a Mach-Zueda interferometer.
(B)).

FIG. 9 is a plan view showing a configuration of an optical waveguide device having an arrayed waveguide grating.

FIG. 10 is a perspective plan view showing a configuration of a phase-type optical waveguide including a ring resonator.

FIG. 11 is a graph showing wavelength characteristics of a ring resonator.

FIG. 12 is a plan view showing a configuration of a conventional arrayed waveguide grating.

[Explanation of symbols]

1 ... core, 2, 14 ... clad layer, 3, 11, 41,
51, 71: substrate, 12: core layer, 13: resist, 30: optical waveguide, 31: X-ray intensity modulation mask, 3
2 ... irradiation chamber, 33 ... introduction tube, 34 ... diaphragm, 40 ... directional coupler, 4, 42, 52, 72 ... input / output port
50: Mach-Zueda interferometer, 60: Array waveguide grating, 62: Input / output waveguide, 63: Slab waveguide, 64
... array waveguide, 65 ... phase adjustment film, 70 ... ring resonator, C ... coupling part, G ... gap, L ... coupling length, β ...
Phase constant

Claims (10)

[Claims] 1. A clad glass layer to be a clad is formed on a substrate, a plurality of cores having a higher refractive index than the clad are embedded in the clad glass layer, and at least one input port and one output port are formed. In the phase-type optical waveguide having, among the plurality of cores, at least one core or a clad around the core is irradiated with X-rays to change a refractive index of the core or the clad, and the core and the clad are changed. A phase-type optical waveguide, wherein the phase of light propagating between the cladding and the cladding is adjusted. 2. A clad glass layer to be a clad is formed on a substrate, a plurality of cores having a higher refractive index than the clad are embedded in the clad glass layer, and at least one input port and one output port are formed. A first step of forming a phase-type optical waveguide having at least one core of the optical waveguide or a clad around the core while monitoring characteristics of the optical waveguide.
A second step of irradiating a line to change the refractive index of the core or the clad to adjust the phase of light propagating between the core and the clad. Manufacturing method. 3. A clad glass layer to be a clad is formed on a substrate, and two cores having a higher refractive index than the clad are buried in the clad glass layer. A phase-type optical waveguide having one end connected to at least one input port and the other end connected to two output ports, wherein the two cores in the coupling portion are By irradiating at least one core or the clad around the core with X-rays to change the refractive index of the core or the clad, the phase of light propagating between the core and the clad was adjusted. A phase type optical waveguide characterized by the above-mentioned. 4. A clad glass layer to be a clad is formed on a substrate, and two cores having a higher refractive index than the clad are buried in the clad glass layer. A first step of forming a phase-type optical waveguide having one end of the two cores connected to at least one input port and the other end connected to two output ports; Light is input from one input port of the waveguide, and at least one of the two cores in the coupling unit is monitored while monitoring the power of the output light from the two output ports.
A second step of irradiating the core of the book or the clad around the core with X-rays to change the refractive index of the core or the clad, and adjusting the phase of light propagating between the core and the clad. A method for manufacturing a phase-type optical waveguide, comprising: 5. A clad glass layer to be a clad is formed on a substrate, and two cores having a higher refractive index than the clad are embedded in the clad glass layer, and the two cores are joined at two locations. And one end of the two cores is connected to at least one input port, and the other end is a phase-type optical waveguide connected to two output ports. By irradiating at least one core or the clad around the core with X-rays to change the refractive index of the core or the clad, the phase of light propagating between the core and the clad was adjusted. A phase type optical waveguide characterized by the above-mentioned. 6. A clad glass layer to be a clad is formed on a substrate, and two cores having a higher refractive index than the clad are embedded in the clad glass layer, and the two cores are joined at two locations. A first step of forming a phase-type optical waveguide in which one end of the two cores is connected to at least one input port and the other end is connected to two output ports; While inputting light from one input port of the optical waveguide and monitoring the output power of two output ports,
At least one core or the clad around the core in the middle of the two coupling portions is irradiated with X-rays to change the refractive index of the core or the clad and propagate between the core and the clad. And a second step of adjusting the phase of the light to be emitted. 7. A clad glass layer to be a clad is formed on a substrate, a plurality of cores having a higher refractive index than the clad are embedded in the clad glass layer, and one end of each of the plurality of cores is A phase-type optical waveguide connected to at least one input port via a slab waveguide and the other end connected to at least two output ports via a slab waveguide; By irradiating the core of the book or the clad around the core with X-rays to change the refractive index of the core or the clad, the phase of light propagating between the core and the clad is adjusted. A phase-type optical waveguide. 8. A clad glass layer to be a clad is formed on a substrate, a plurality of cores having a higher refractive index than the clad are embedded in the clad glass layer, and one end of the plurality of cores is a slab. A first step of forming a phase-type optical waveguide connected to at least one input port via a waveguide and the other end connected to at least two output ports via a slab waveguide; While inputting light from one of the input ports and monitoring the output power of the output port, at least one core of the optical waveguide or a clad around the core is irradiated with X-rays to refract the core or the clad. A second step of adjusting the phase of the light propagating between the core and the clad by changing a rate. 9. A clad glass layer to be a clad is formed on a substrate, one core having a higher refractive index than the clad is embedded in the clad glass layer, and the one core is connected to one input port. And a single output port, and a phase-type optical waveguide in which a ring-shaped core is disposed optically coupled to the one core by providing a gap with the core in an intermediate portion of the core, The ring-shaped core or the cladding around the core is irradiated with X-rays to change the refractive index of the core or the cladding, and propagates between the ring-shaped core and the cladding around the core to resonate. A phase-type optical waveguide, wherein the phase of light is adjusted. 10. A clad glass layer to be a clad is formed on a substrate, one core having a higher refractive index than the clad is embedded in the clad glass layer, and the one core is connected to one input port. Has one output port,
A first step of forming a phase-type optical waveguide in which a ring-shaped core is optically coupled to the one core to form a phase-type optical waveguide by providing a gap with the core in an intermediate portion of the core; While inputting light from the input port of the optical waveguide and monitoring the output power of the output port, the ring-shaped core or the clad around the core is irradiated with X-rays to change the refractive index of the core or the clad. A second step of adjusting the phase of light that propagates and resonates between the ring-shaped core and the clad around the core, thereby producing a phase-type optical waveguide.