WO1997047998A1 - Optical waveguide and optical device - Google Patents

Abstract

An optical waveguide of a system in which the diameter of a core is constant in the optical wave propagation direction with the diameter of a mode field at input and output ends increased by reducing Δn toward the input and output ends, a difference Δn between refractive indexes of a core and a clad of the waveguide along the optical wave propagation direction for improving a coupling efficiency and tolerance in a connecting operation having a Δn variation region in which Δn varies from Δn1 to Δn2 (Δn1 > Δn2), a cross-sectional shape of the core not varying in the optical wave propagation direction, characterized in that an X-Y plot in which the X and Y axes represent the coordinates of Δn variation region in the optical wave propagation direction and Δn respectively projects downward, and an optical fiber.

Description

 Specification

 Optical waveguides and optical devices

 The present invention relates to a mode field diameter conversion optical waveguide, an optical fiber, an optical switch, an optical input / output device, and a method of manufacturing an optical waveguide. Background art

 In order to solve the problems related to the connection of optical waveguides, optical fibers, laser diodes, etc., which are the components of an optical communication network, the mode field diameter of the guided light in these devices Research and development to convert is underway. The importance of mode field diameter conversion technology is attracting attention because it has the following effects.

The first effect is to reduce the positioning accuracy in connecting optical waveguides and optical fibers. When connecting a single-mode waveguide or optical fiber, it is necessary to adjust the optical axis in the micron order. If the mode field diameter conversion technology can increase the mode field diameter at the connection part, the tolerance of the connection can be reduced. The second effect is higher connection efficiency of optical elements having different mode field diameters. The connection between the high Δη optical waveguide and the normal Δη optical waveguide, or the connection between the waveguide and the laser diode, is due to the difference in the mode fields at the respective input / output end faces. The problem is that the resulting coupling loss at the connection is large. By matching the mode field diameter at the connection part by the mode field diameter conversion, the connection can be made more efficient. The third effect is that the connection between optical waveguides and optical fibers is This is an increase in the gap between the end faces. If the mode field diameter at the end face can be increased, the diffraction loss can be reduced and the gap between the end faces can be increased, and as a result, the thickness of the optical element that enters between the gaps can be reduced. Restrictions can be relaxed.

Various researches have been conducted on the mode field diameter conversion technology that produces the above effects. Japanese Patent Application Laid-Open No. 6-174980 discloses that a core size at an input / output end is expanded by a double core structure in which two types of tapered cores are superimposed at a waveguide input / output end. I do. Japanese Patent Application Laid-Open No. 6-43330 discloses a mode filter by heating an input / output end face of a quartz waveguide and locally diffusing a dopant in a core at the input / output end face. Disclosed is a mode conversion circuit for increasing the diameter of a node. In this case, the core diameter increases as it approaches the end face, but the refractive index of the core decreases, so that the normalized frequency of the waveguide or optical fiber is constant in the light wave propagation direction. JP-A-1 96 604, the I'm particular irradiation with C 0 ₂ laser quartz waveguides, allowed change the refractive index of the core in the optical wave propagation direction, earthenware pots by the waveguide itself has the function of a lens The disclosed optical device is disclosed.

Also, Journal of Lightwave Technology LT one 5 Certificates No. 9 1 2 4 6 - 1 2 In 5 one page, control the expansion Chiryou to de one Bruno down bets at which T i of L i N b 0 ₃ in Thus, a method of manufacturing a waveguide for converting a mode field is described.

 As described above, various attempts to increase the mode field diameter at the input and output ends of the waveguide have been reported. However, these methods have the following problems.

The method disclosed in Japanese Unexamined Patent Application Publication No. 6-4980, in which two types of tapered cores are superposed at the input and output ends of a waveguide, has a problem that the manufacturing method is complicated. There is.

 Japanese Patent Application Laid-Open No. 6-43330 discloses a method of enlarging the mode diameter by locally diffusing the dopant in the core of the quartz waveguide at the input and output ends. It is necessary to heat the end face of the waveguide to 100 ° C. or higher. There is a limit in controlling the temperature of the waveguide locally at such a high temperature, and therefore, the refractive index distribution is produced as designed. It is very difficult to do. In addition, in this method, the same heat distribution must be applied to two adjacent waveguides in the waveguide array, and the mode diameter of only one of the waveguides needs to be converted. In such cases, application of this method is difficult.

Disclosed in JP-A-1 one 96604 discloses a quartz waveguide obtained I'm particular irradiation with C 0 ₂ laser, the optical Device Lee scan the waveguide itself has the function of a lens, the Hare yo follows Problem. Said expression be one C 0 ₂ laser refractive index of silica I by the irradiation of utilizing the property of increasing, take the following Yo I Do fabrication process. On the lower quartz cladding formed by the flame deposition method, a quartz core containing a dopant and having a higher refractive index than the cladding is formed by the flame deposition method. In here, along the propagation direction of the light irradiating the C 0 ₂ laser, the amount of irradiation and Control This setup roll, to form a refractive index distribution in the light wave propagation direction. A waveguide core is formed by an etching process, and finally an upper clad is formed by a flame deposition method.

Irradiating the core with the laser increases the refractive index of the core.At this time, the lower cladding is also irradiated with light, so the refractive index distribution on the lower cladding along the light wave propagation direction Is formed. Since the refractive index of the upper clad formed after laser beam irradiation is constant in the light wave propagation direction, the difference in the refractive index between the lower clad and the upper clad is different in the light wave propagation direction. As a result, the symmetry of the waveguide is lost and the polarization dependence of the propagating light occurs. There were issues such as living. There are also the following problems. It condenses the C 0 ₂ laser beam Ru long wavelength light der to be small region Ri by the width of the waveguide is very difficult. For irradiation width of C 0 ₂ laser is greater Ri by core width, the width of the refractive index increasing portion of the lower click La head even wider Ri by its core. Therefore, the refractive index contours of the waveguide cross section are not concentric, and a concave curve may be generated as a contour, resulting in a disturbed beam pattern. After the core refractive index profile is formed, the upper cladding is formed by fire deposition, but the waveguide is placed under high temperature conditions to sufficiently sinter the upper cladding. In addition, there is a problem that the refractive index distribution of the core disappears. In order to avoid this, the upper cladding sintering temperature has to be set lower at present, but the sintering of the upper cladding will be insufficient. A method by thermal diffusion of de one pan bets by the heat distribution forming, a method by co ₂ laser irradiation, because it requires more processes in 1 0 0 0, electro - low temperature cormorants good optical hybrid circuits If it is necessary to make it by using it, its application is difficult.

 J ournal of L i ghtwave T echno l ogy LT Vol.5 No.9 I246-1251 says that it is difficult to form the upper cladding after the core is made There's a problem.

 SUMMARY OF THE INVENTION An object of the present invention is to provide a Δη control optical waveguide and a method of manufacturing the same that can solve the problems of the above-described conventional mode diameter enlarging method. An object of the present invention is to provide an optical waveguide and an optical fiber with optimized η distribution conditions. Disclosure of the invention

The present invention is achieved by the following description. The gist is 1. In an optical waveguide whose mode field diameter increases or decreases at the input / output end, the optical waveguide is made of a polymer, and the core of the core in the optical waveguide cross-section perpendicular to the light wave propagation direction. An optical waveguide, wherein the size is constant irrespective of the position of the optical waveguide, and a difference in refractive index between the core and the clad changes along the light wave propagation direction.

 2. In an optical waveguide where the mode field diameter increases or decreases at the input / output end,

 The optical waveguide is made of a polymer,

 The size of the core in the cross section of the optical waveguide perpendicular to the light wave propagation direction is constant irrespective of the position of the optical waveguide,

 The refractive index of the cladding is constant,

 The refractive index of the core changes along the light wave propagation direction

An optical waveguide characterized by this.

 3. The optical waveguide according to claim 1 or claim 2,

 The core is composed of a polymer in which a pigment that increases the refractive index of the core when mixed with the polymer is dispersed or bonded,

 An optical waveguide, wherein the dye content of the core changes along a light wave propagation direction.

 4. In the method for manufacturing an optical waveguide according to item 3,

 Controlling the amount of light irradiation on the core to form a refractive index distribution in the light wave propagation direction of the core;

A method for manufacturing an optical waveguide, comprising:

 5. In an optical waveguide where the mode field is enlarged or reduced at the input and output ends,

The optical waveguide is made of a fluorinated polymer, The fluorine content of the light wave propagation portion of the optical waveguide changes along the light wave propagation direction

An optical waveguide characterized in that:

 6. The optical waveguide according to item 5, wherein a size of a core at a cross section of the optical waveguide perpendicular to a light wave propagation direction is constant regardless of a position of the optical waveguide.

 7. In the optical waveguide described in item 5 or 6,

The fluorinated polymer is a polymer represented by the above chemical formula, and a polymer obtained by introducing 1 C „F _{2in + 1} (m = l to 5) into the polymer as an anonymous group. An optical waveguide, comprising:

 8. In the method for manufacturing an optical waveguide described in Paragraph 5 or 6 or 7,

 The electron irradiation increases the refractive index of the fluorinated polymer,

 By changing the amount of irradiated electrons in the light wave propagation direction,

 The refractive index of the electron beam irradiated part changes in the light wave propagation direction

A method for manufacturing an optical waveguide, comprising:

9. The method for manufacturing an optical waveguide according to item 8, comprising: A method for manufacturing an optical waveguide, characterized in that the laser beam and the electron beam irradiation width are constant in the light wave propagation direction of the optical waveguide.

 10. In the method of manufacturing an optical waveguide according to item 8 or 9, the electron beam is irradiated so that the electron beam irradiation density inside the polyimide thin film is higher than the surface of the polyimide thin film. Irradiate,

 Guide light inside the polyimide film

A method for manufacturing an optical waveguide, comprising:

 11 1. In the optical waveguide according to any one of Items 1, 2, 3, 5, 6, 6 and 7,

 An optical waveguide characterized in that the contours of the refractive index distribution in the cross section of the optical waveguide consist only of convex curves.

 1 2. There is a Δη change region in which the refractive index difference m n between the waveguide core and the clad changes from Δη ΐ to m n2 (m nl> A n 2) along the light wave propagation direction. The purpose of this is to change the mode diameter of the propagating light in the Δη change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. In the optical waveguide for

 An optical waveguide characterized in that an X-Υ plot, in which the coordinates of the Δη change region along the light wave propagation direction are the X-axis and Δη is the Υ-axis, is convex downward.

 1 3. Along the light wave propagation direction, the Δη change region where the refractive index difference Δη between the waveguide core and the clad changes from Δηΐ to Δη2 (Δη1> Δη2) Single mode in which the cross-sectional shape of the core does not change along the light wave propagation direction, with the purpose of changing the mode diameter of the propagating light in the Δη change region by having In an optical waveguide for guiding,

The beam diameter in the region where Δ η is Δ η 1 (double the beam radius at which the electric field intensity becomes e when the maximum electric field intensity at the beam center is 1) is d,, The beam diameter in the region where Δη is m n 2 is defined as d ₂ , and the beam expansion ratio dz / d is defined as «. When the two waveguides are connected at the end faces where m η = Δ η 2 When the coupling efficiency is defined as, the coupling efficiency and the beam expansion rate are

 7?>-0.05 X (/-1) + 1 and〉 1.2

An optical waveguide characterized by satisfying the following.

 1 4. A refractive index difference Δη between the waveguide core and the cladding Δη changes from Δηΐ to Δη2 (Δη1> 2η2) along the light wave propagation direction. The purpose of this is to change the mode diameter of the propagating light in the Δη change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. In the optical waveguide for

The X-Υ plot, where the X-axis is the coordinate of the Δη change region along the light wave propagation direction (Χ = 0 to) and the Δ-axis is the Υ-axis, is Δη (Χ) = Δη1 — (A n 1 — A n 2) x (X / L) ^{0 1} and Δ η (Χ) = Δ η 1 one (Δ η 1 one Δ η 2) X (X / L) ° · ⁷⁶ An optical waveguide characterized by being in a region surrounded by a curved line represented by the curve.

 1 5. There is a mu η change region where the refractive index difference Δ η between the waveguide core and the cladding changes from mu nl to Δ η 2 (Δ η 1〉 Α η 2) along the light wave propagation direction. The purpose of this is to change the mode diameter of the propagating light in the mu η change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. In the optical waveguide for

 The Χ-Υ plot, with the coordinates of the Δη change area along the light wave propagation direction as the X axis (X = 0 to L) and Δη as the Υ axis, is Δη (Χ) = Δη1 — (Δ η 1 — An 2) x (XZ L) "(0.1 <ω <0.75). An optical waveguide characterized by a curve represented by the following equation.

1 6. For optical waveguides cut in any of paragraphs 12, 13, 14, and 15 An optical waveguide, wherein the optical waveguide is made of a polymer.

 17. The optical waveguide according to item 16, wherein the core of the optical waveguide is composed of a polymer in which a pigment that increases the refractive index of the core when mixed with the polymer is dispersed or bonded, 3. The optical waveguide according to claim 1, wherein the dye content varies along a light wave propagation direction.

 1 8. In the method for manufacturing an optical waveguide according to item 17

 A method of manufacturing an optical waveguide, comprising: controlling a light irradiation amount on the core to form a refractive index distribution in a light wave propagation direction of the core.

 19. The optical waveguide according to item 18, wherein the waveguide is made of a fluorinated polymer, and the fluorine content of the light wave propagating portion of the waveguide changes along the light propagation direction. An optical waveguide characterized in that Δη changes according to and.

20. In the optical waveguide according to item 19,

And Po Li Lee Mi de of the full Tsu fluorinated poly Ma is denoted by the chemical formula (0 ^ 1), the poly Ma _{- C m F 2m + 1 (} m = l ~ 5) introduced as a substituent An optical waveguide characterized by comprising a modified polyimide.

21. In the optical waveguide according to item 20,

Increase the refractive index of the fluorinated polymer by electron beam irradiation, and increase the amount of irradiated electrons A method of manufacturing an optical waveguide, characterized in that the refractive index of an electron beam irradiated portion changes in the light wave propagation direction by changing the refractive index along the light wave propagation direction.

 2 2. Along the light wave propagation direction, the Δη change region where the refractive index difference Δη between the core and the cladding of the optical path changes from Δη1 to Δη2 (Δη1> Δη2) In the optical waveguide or optical fiber having

 An optical waveguide or an optical fiber characterized in that a Χ-Υ plot with the coordinate of the Δη change region along the light wave propagation direction as the X axis and Δη as the Υ axis is convex downward. .

 23. The Δη change region where the refractive index difference η between the core and the cladding of the optical transmission path changes from Δη1 to Δη2 (Δη1> Δη2) along the lightwave propagation direction. In an optical waveguide or an optical fiber having

An X-Υ plot with the X axis (Χ = 0) as the coordinate of the Δη change region along the light wave propagation direction and the ΔΥ as the Υ axis is given as Δη (Χ) = Δη1-( Δ n 1 — Δ η 2) X (X / L) ° · 'and the curve Δ η (Χ) = Δ η 1-(Δ η 1 one Δ η 2) X (XZ L) °' ⁷⁶ An optical waveguide or an optical fiber characterized by being located in a region surrounded by a curve represented by:

 2 4. Along the optical wave propagation direction, the Δη change region where the refractive index difference Δη between the core and the cladding of the optical path changes from Δη1 to An2 (An1> Δn2) In the optical waveguide or fiber that has

 An X-Y plot with the coordinates of the Δη change region along the light wave propagation direction as the X axis (X = 0 to L) and Δn as the Y axis gives Δη (Χ) = mu η 1 — (mu η 1 —m η 2) X (XZ L) ”(0.1 <ω <0.75). An optical waveguide or an optical fiber characterized by having a curve represented by the following equation.

2 5. In an optical fiber array including an optical waveguide whose mode field diameter at the human output end expands or contracts, terms 1 to 3, 5 to 7, 11 to 17, 19, and 20. An optical fiber array comprising the optical waveguide or the optical fiber described in any one of 20 to 22 to 24.

 26. In an optical fiber array that includes an optical waveguide whose mode field diameter at the input / output end expands or contracts,

 An optical waveguide whose mode field diameter does not change, and any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20, 22 to 24. Optical waveguide or optical fiber is placed adjacent to

An optical fiber array, characterized in that:

 27. Mode field diameter at the input / output end described in any one of items 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24 An optical input / output device that includes an optical waveguide that expands or contracts.

 2 8. In the connection mode of an optical waveguide and an optical waveguide or an optical fiber having a core diameter larger than the core diameter of the waveguide,

 The optical waveguide on the side with the smaller core diameter is the Δη control waveguide described in any one of Items 1-3, 5-7, 11-17, 19, 20 and 22-24. A connection form characterized by:

 2 9. Includes a 基板 -shaped polymer waveguide and a heating means for locally heating the waveguide, and an optical path switching switch substrate for switching the optical path of the waveguide by a local temperature change of the polymer. An optical path switching device including an optical fiber or an optical waveguide for introducing input light into the optical path switching switch substrate or deriving output light from the optical path switching switch substrate. , A light path switching device comprising the η control waveguide according to any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20, 22 to 24. .

3 0 .—One or more transmitting optical waveguides or fibers and two or more receiving optical waveguides Select only one receiving optical waveguide or optical fiber to be connected to the emitting end of the transmitting optical waveguide or optical fiber, and to select only one receiving optical waveguide or optical fiber. Alternatively, by connecting an optical fiber to a transmitting waveguide or an optical fiber, a specific receiving optical waveguide or an optical fiber to another receiving optical fiber. In an optical switch that switches an optical path of an optical signal to an optical waveguide or an optical fiber,

 Item 1 to 3, 5 to 7, 11 to 17, 19, 20, 22 to 24, including the optical waveguide or the optical fiber described in any one of the above. Light path switching switch.

 3 1 .—Includes one or more outgoing optical waveguides or optical fibers and two or more receiving optical waveguides or optical fibers, with the outgoing end of the outgoing optical waveguide or optical fiber. By selecting only one receiving optical waveguide or optical fiber to be connected, and connecting the selected waveguide or optical fiber to the transmitting optical waveguide or optical fiber, In an optical switch that switches the optical path of an optical signal from a specific receiving optical waveguide or optical fiber to another receiving optical waveguide or optical fiber,

 Item 12 to 17, 19, 20, 22 to 24, including two or more optical waveguides or optical fibers according to any one of the above, and two optical waveguides or optical fibers. An optical path switching switch characterized in that an optical waveguide or an optical fiber is connected by abutting an end face having a diameter n of Δη2.

3 2 .—Including one or more transmitting optical waveguides or fibers and two or more receiving optical waveguides or fibers, the emitting end of the transmitting optical waveguide or fiber. By selecting only one receiving optical waveguide or optical fiber to be connected to the transmitter and connecting the selected waveguide or optical fiber to the transmitting waveguide or the optical fiber. Separate from the specific receiving optical waveguide or fiber. In the optical switch that switches the optical path of the optical signal to the receiving optical waveguide or optical fiber of

 A plurality of parallel cantilevered beams formed on a silicon substrate and connected by a connecting member; an optical waveguide formed on at least one cantilever; A plurality of optical waveguides fixed to face the waveguide, and switch driving means for deforming the cantilever; and an optical waveguide formed on the cantilever and the fixed optical waveguide. An optical switch characterized in that both are optical waveguides according to any one of Items 1 to 3, 5 to 7, 11 to 17, 19, 20, and 22 to 24.

 3 3. In an optical input / output device including a laser diode, an optical waveguide in which the laser oscillation wavelength light is guided in a single mode in a fiber, and an optical fiber,

 The optical waveguide is the optical waveguide according to any one of Items 12 to 17, 19 and 20, and the optical fiber is the optical waveguide according to any one of Items 22 to 24. The optical fiber described above, characterized in that the optical waveguide and the optical fiber are connected by abutting an end face where Δη of the optical fiber and Δη are Δη2. I / O device to perform.

 3 4. In an optical waveguide with an optical element or an optical fiber in which an optical element such as a wavelength selection filter or a polarizing element is pushed between optical fibers or optical fibers, an optical waveguide sandwiching the optical element. Is the region including the end face of the optical fiber on the optical element side, as described in any one of the items 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24. An optical waveguide with an optical element or an optical fiber, which is an optical waveguide or an optical fiber.

3 5. An optical input / output device including a laser diode, an optical waveguide in which the laser oscillation wavelength light is guided in a single mode in a fiber, and an optical fiber. And the optical waveguide or optical fiber described in the items 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24. Optical input / output device.

36. The laser diode and the laser oscillation wavelength light are guided in a single mode in the fiber, and the mode diameter of the mode is different from the mode diameter of the laser beam at the emission end of the laser diode. In an optical input / output device including an optical fiber and

 Between the laser diode and the optical fiber, the refractive index difference Δη between the waveguide core and the cladding along the light wave propagation direction is Δη1 from Δη1 to Δη2 (μη1 >〉 η2). The purpose is to change the mode diameter of the propagating light in the Δη change region by having the An change region that changes in There is an optical waveguide for single mode waveguide that does not exist, and the mode of the waveguide on the laser diode side end face of the optical waveguide is set so that the coupling efficiency between the laser diode and the optical waveguide is 90% or more. The mode on the optical fiber side end face of the optical waveguide should be such that the diameter matches the mode diameter of the laser diode and the coupling efficiency between the optical waveguide and the optical fiber is 90% or more. Light whose diameter is equal to the mode diameter of the optical fiber Person output device.

Further, according to the present invention, the refractive index difference Δη between the core and the cladding of the waveguide changes from Δηΐ to μη2 (Δη1>Δη2>) along the lightwave propagation direction. The purpose is to change the mode diameter of propagating light in the Δη change region by having the η change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. In the optical waveguide for mode guiding, the beam diameter in the region where Δ η is △ η 1 (two times the beam radius at which the electric field intensity becomes e− ² when the maximum electric field intensity at the beam center is 1) is When the beam diameter in the region where d,, Δ η is Δ η 2 is defined as d ₂ , and the beam expansion rate is defined as d ₂ Z d, The plots of coupling efficiency and beam expansion ratio when end faces where n is 2

Effect

rate

 1.0 1.5 2.0 2.5 3.0

 Beam expansion ratio We propose an optical waveguide characterized by being in the hatched area in the above figure.

Hereinafter, the present invention will be described more specifically. Along the light wave propagation direction, there is a refractive index difference Δη between the core and the cladding of the waveguide, and a Δη changing region that changes from 'Δη1 to mu η2 (Δη1> Δη2). In an optical waveguide in which the cross-sectional shape of the core does not change along the light wave propagation direction, parameters such as Δη Δ, Δη 2, the length L of the refractive index change region, and the light wave propagation direction It is necessary to set a distribution function form Δη (Χ) of Δη when the coordinates of the Δη change area are X coordinates. Here, Δηΐ is an amount determined from the single-mode waveguide condition of the waveguide. For example, the refractive index of the clad is 1.5, and the cross-sectional shape of the waveguide is 8 が 8. When examining the waveguide of 1.3 tm light with μ πι ² , Δ η 1 = 0.045 from the condition of single mode waveguide. In order to improve the coupling efficiency in the connection of waveguides and to increase the tolerance, we set Δη from Δη1 to Δη2 (Δη1) 112 along the light wave propagation direction. ) Change to 11) change The following results were obtained as a result of fabricating and examining an optical waveguide having a region and the cross-sectional shape of the core not changing along the light wave propagation direction.

 First, the dependence of the coupling efficiency and the tolerance on the length L of the refractive index change region was investigated. When the distribution function Δη (Χ) of the nl, Δη2, and Δη is fixed and only the refractive index change region length L is used as a parameter, the refractive index change region length L becomes longer. Therefore, it was found that the characteristics of both the coupling efficiency and the allowable deviation were improved. Here, the deviation tolerance is a quantity representing the degree of tolerance and is defined as follows. The end faces of the two waveguides are attached to each other, light is propagated from one waveguide to the other waveguide, and the intensity of the propagated light is measured. When the output light intensity is measured while displacing one waveguide in the vertical direction with respect to the waveguide, the difference between the position where the maximum output light intensity is given and the position where the lZe output intensity is given is the deviation tolerance. Define. The coupling efficiency is defined as the maximum propagating light intensity when the waveguides are connected to each other with a constant Δn of Δn 1 and an intensity ratio therewith.

However, in an actual device, the length L of the refractive index change region cannot be unlimited due to the size limitation. Therefore, next, the dependence of the coupling efficiency and deviation tolerance on Δη 2 and the refractive index distribution function form Δη (Χ) when the refractive index change region length L is fixed was examined. As a result, the following findings were obtained. When the length L of the refractive index change region is sufficiently long, for example, 3 mm or more, the coordinates of the Δη change region along the light wave propagation direction are defined along the X-axis ( X = 0 to L), and the X-Y plot with Δη as the Y axis is expressed as Δη (Χ) mm η1 — (Δη1 — Δη2) χ (XZL) ” In this case, when 0.1 <ω <0.75, excellent characteristics can be obtained with respect to the coupling efficiency of the connection and the tolerance for deviation.In particular, ω = 0.2 to 0.33 is optimal It is not always necessary to take the above function form, and these functions are approximated. With the number form, it is possible to obtain excellent coupling efficiency and tolerance of deviation. In addition, if the X-Υ plot, in which the coordinates of the Δη change region along the light wave propagation direction are the X axis and Δη is the Υ axis, is convex downward, characteristics close to these optimal conditions should be obtained. Can be. Even if the projection is not convex downward, the X—Υ plot, where the coordinates of the Δη change area along the light wave propagation direction are the X axis (X = 0 to L) and Δη is the Y axis, is Δη (Χ) = Δ η 1 — (Δ η 1-Δ η 2) x (X / L) ° · ¹ and the curve expressed by Δ η (Χ) = Δ η 1 one (Δ η 1 — Δ η 2 ) X ((/ L) °) It was found that in the region surrounded by the curve represented by ⁷⁶ , excellent characteristics can be obtained in connection coupling efficiency and deviation tolerance.

The coupling efficiency and the allowable deviation value in the optimal Δη distribution function form Δη (求 め) obtained as described above depend on the set value of η2. For example, class Tsu refractive index of the soil 1.5 5 0, core cross-section is ^{8 χ 8 μ ηι 2, Δ} η 1 = 0. 0 0 4 5, L = 5.4 mm, Δ η (Χ) = Δ η 1-(Δ η 1-Δ η 2) Χ (XZ L). Under the condition of ^2, the coupling efficiency is 98% when Δη 2 = 0.012, the coupling is 10 μπι when the allowable deviation is 10 μ, and the coupling is when Δη 2 = 0.009. When the efficiency is 97% and the allowable deviation is 13 μιη, Δη2 = 0.006, the coupling efficiency is 90% and the allowable deviation is as follows. For a constant waveguide, the allowable deviation is 6 μιη. There is a trade-off between the coupling efficiency when Δη 2 is a parameter and the allowable deviation.The higher the coupling efficiency, the lower the tolerance, and the higher the tolerance, the higher the coupling. Efficiency decreases. Since such a trade-off relationship exists, it is necessary to set the value of η 2 according to the use or purpose of the optical waveguide.

The optical waveguide can be manufactured, for example, by the following method. The same type of polymer or a polymer with almost the same refractive index is used for the core and the cladding of the optical waveguide, and the core is made of a dispersive thread 1 (DR 1). By mixing with the polymer, the refractive index of the polymer is increased, and at the same time, a dye is added that causes bleaching (bleaching) by light irradiation and lowers the refractive index. The incorporation of this dye makes the refractive index of the core higher than that of the clad and forms a waveguide. The dye may be dispersed in the polymer or may be in a state of being bound to the polymer.

 Next, the core is irradiated with light absorbed by the dye in the core, thereby locally reducing the refractive index of the core. Here, since the width of decrease in the refractive index can be controlled by the amount of light irradiation, by changing the irradiation time along the propagation direction of light in the waveguide, The refractive index distribution in the light wave propagation direction can be formed on the core. At this time, light irradiation may be performed before patterning the core on a straight line, a curve, or the like, or light irradiation may be performed after patterning. If the irradiated light is sufficiently transmitted through the cladding, the core is patterned, the upper cladding is formed, and then the light is irradiated to form the core refractive index distribution in the light wave propagation direction. You can do it. When the irradiation light is not absorbed by the cladding substrate, light irradiation can be performed from both above and below the core, so that there is no unevenness in the waveguide cross section.

It is desirable that the irradiation light is not absorbed by the cladding and the substrate, because it can generate bl each inng.

 In the above description, an example was given in which DR 1 was used as a dye for increasing the refractive index. However, the dye is such that when mixed with a polymer, the refractive index of the molecule increases, and However, any molecule whose refractive index is reduced by light irradiation, electron beam irradiation, ion beam irradiation, or the like can be used as a dye molecule mixed into a polymer.

The optical waveguide of the present invention can be manufactured even with a polymer whose refractive index changes by light irradiation, electron beam irradiation, or ion beam irradiation. As a polymer having such properties, for example, a fluorinated polyimide is used. Fluorinated polyimides are described in Applied Optics, Volume 34, page 104.

 As shown in (1995), it has the characteristic that the refractive index increases by electron beam irradiation. Since the refractive index of the part irradiated with the electron beam changes according to the irradiation amount of the electron beam, an appropriate dose is applied to the region where the core of the waveguide is to be formed.

 By irradiating a (Dose) amount of electron beam, it is possible to draw a waveguide. The width of the core can be controlled by the irradiation area of the electron beam. In addition, since the core depth can be controlled by the energy of electrons, a core of a desired size can be formed. Here, by controlling the irradiation amount of the electron beam along the light wave propagation direction of the waveguide, it is possible to produce an optical waveguide whose refractive index changes along the same direction. it can. At the time of drawing, the electron beam source may be fixed and the polymer film may be destroyed, or the polymer may be fixed and the electron beam source may be moved.

By forming a polyimide layer with the same or similar structure on the drawn film by spin coating and imidization, the lower cladding, core, and upper cladding can be used. Can be manufactured. At this time, the refractive index distribution of the core does not change even after the upper clad is imidized. The Chi Scenery, a quartz optical waveguide is irradiated Ri by the C 0 ₂ laser, in JP-1- 96604 JP method of forming a refractive index distribution, in order to save the refractive index profile of the core, upper click La Although the sintering of the head may be insufficient, such a problem does not occur in the method of the present invention.

The shape of the optical waveguide manufactured in this manner in a cross section perpendicular to the light wave propagation direction, that is, the shape of the portion where the refractive index is changed by the electron beam, depends on the irradiation width of the electron beam and the energy of the electron. In addition, since the refractive index of the portion not irradiated with the electron beam is constant, the optical waveguide can be controlled. It is symmetrical and has little polarization dependence.

 The polyimide used in the present invention covers all polyimides whose refractive index can be controlled by electron beam irradiation. For example, a polyimide alone or a polymer which can be produced from the following tetracarboxylic acid or a derivative thereof and a compound in which some or all of the hydrogen atoms in diamine are substituted with fluorine atoms. Examples include mid copolymers, polyimide mixtures, and those to which additives are added as necessary.

 Tetracarboxylic acid is composed of pyromellitic acid, methylpyromellitic acid, dimethylpyromellitic acid, dibutyl pyrpyromellitic acid, ethylpyromellitic acid, bis {3,5-dimethylphenic acid. Nonoxy} pyromellitic acid.

 In addition, 2,3,3 ', 4'-biphenyltetracarboxylic acid, 5,5'-dimethyl-3,3', 4,4'-tetraphenylpropoxybiphenyl, 2,2 ', 5, 5'-tetramethyl-3-, 3 ', 4,4'-tetracarboxybiphenyl, 1,4-bis (3,4-dicarboxyphenoxy) biphenyl, bis {(methyl) dicaroxyphenoxy } Biphenyl, bis {(methyl) dicarboxyphenyl} (dimethyl) biphenyl and bis (dicarboxyphenyl) (dimethyl) biphenyl.

In addition, 3,3 ', 4,4'-tetracarbodidiene ether, 2,3,3', 4'tetracarboxylicdiene ether, 5,5'-dimethyl 3,3 ', 4,4'-Tetracarboxydiphenyl, bis {(methyl) dicarboxyphenoxy} diphenyl, 3,3', 4,4'-Benzofu Nontetracarboxylic acid, 5,5'-Dimethyl-3,3 ', 4,4'-Tetracarboxybenzophenone. Also, 2,3,6,7-tetracarboxinaphthalene, 1,4,5,7—tetracarboxinaphthalene, 1,4,5,6—tetracarboxy Naphthalene, 3,3 ', 4,4'-tetraphenyldimethoxyphenyl, 2,2-bis (3,4-dicarboxyphenyl) pronone, 2,2-bis {4 3,4 dicarboxyphenyl) propane.

 Butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, 1,4-bis (3,4-dicarboxyphenoxy) benzene, bis {(methyl) dicarboxyphenoxy} benzene, bis {(methyl) Dicarboxyphenoxy} (methyl) benzene, bis (dicarboxyphenoxy) (methyl) benzene, bis (dicarboxyphenoxy) (dimethyl) benzene, bis (dicarboxyphenoxy) (tetramethyl) benzene There is.

 Also, 3,3 ', 4,4'-tetracarboxydiphenylsulfone, 3,4,9,10-tetracarboxyperylene, bis (3,4-dicarboxyphenyl) dimethylsilane, 1, 3-bis (3, 4-dicarboxy phenyl) tetramethyldisiloxane and the like.

Examples of Jimin include the following. 1,3-Diaminobenzene, 1,4-Diaminobenzene, 2,4-Diaminotoluene, 2,5-Diaminotoluene, 2,4-Diaminoxylene, Dimethylphenylenediamine, 2,4 diaminodulene, 2,3,5,6—tetramethyl-1-p—phenylenediamine, diamino-1-tetramethylbenzene, diaminoethylbenzene, 2,5— Diaminohexyl benzene, 2,5 diamino monobutyl benzene, 4 decanoloxy 1,3,3-diamino benzene, 4-butanoloxy 1,3,3-diamino benzene, 4 —Heptanoxyl 1,3—Diaminobenzene, 4-octanoloxy 1,3—Diamino benzene, 4-Phenoxy 1,3,3-Diaminobenzene, 4-Hexane 1,3-diaminobenzene and 4-dodecanoxy 1,3-diaminobenzene. 1,4-bis (p-aminophenyl) benzene, p-bis (4-amino-2-methylphenoxy) benzene, bis (aminophenol) (dimethyl) benzene, bis (Aminophenoxy) (tetramethyl) benzene, bis {2 — [(Aminophenoxy) phenyl] isopropyl} benzene, 1,4-bis (3-aminopro There is benzene.

 Also, 2,2'-dimethyl-4,4'-diaminobiphenyl,

3'-Dimethyl-4,4'-diaminobiphenyl, 4,4'diaminophoxybiphenyl, bis {(methyl) aminophenoxy} biphenyl, 4,4 ' -Diamino diphenyl ether, 3,3'-dimethyl-4,

4'-Diaminodiethyl, 2,2'-Dimethyl-4,4'-Diaminodiethyl, 3,3 ', 5,5' Tetramethyl-4, Diazimi There is no diphenyl ether.

Also, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,2-bis (anilino) ethane, 2,2 — Bis (p-aminophenyl) propane, 1,3—Bis (a2rino) propane, 2,2—Bis {4-1 (2—aminophenoxy) phenyl} propane , 2,2—bis {4-1- (3—aminophenol) phenyl}, 2,2—bis {4-1- (4—aminophenol) phenyl } Propane, 2,2—bis {4— (4-aminophenol) -1,3,5—dimethylphenyl} 2,2,2-bis {4-1- (4-amino) No 3 —methyl phenyl) propane, 1,4-bis (anilino) butane, 1,5-bis (anilino) pentane, 1,7—bi (Anilino) heptane. In addition, 4,4'-diaminodiphenylsulfone, 4,4'-bis (3-aminophenylphenyl) diphenylsulfone, 4,4'-bis (4-aminophenyl) —Methylphenoxy) diphenylsulfone and 4,4'-bis (3-amino-5-methylphenoxy) diphenylsulfone.

 Also, 3,3'-dimethyl-4,4'-diaminobenzophenone, 4,4 "-diamino-p-terphenyl, 4,4 '' ''-diamino 1-p-quaterphenyl, diaminoanthraquinone, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, benzidine, 2,2'- Dimethylbenzidine, 3,3'-Dimethylpentidine, 3,3 'Dimethoxidine, 2,2'-Dimethoxybenzidine, 3,3', 5,5 'Tetramethylbenzidine, 3,3' Diacetylpentizidine, bis (4-aminophenyl) sulfide, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, bis (4-aminophenyl) Getylsilane and the like.

 Here, the method of irradiating an electron beam using a fluorinated polyimide is described. In this method, the refractive index changes due to light irradiation, electron beam irradiation, and ion beam irradiation. It can be carried out using another polymer that satisfies the conditions.

 The refractive index contour of the cross section of the optical waveguide formed by this method consists of only a convex curve, and the beam pattern has little disturbance.

In the present invention, a method that does not require the formation of the upper clad after the electron beam drawing can be realized. At the time of electron beam irradiation, the electron beam is forcibly forced to increase the electron beam irradiation density inside the film compared to the surface of the polyimide film, and the inside of the polyimide film is refracted. By increasing the efficiency, the propagating light will be guided through the inside of the polyimide film, and a new upper cladding must be formed. Disappears.

The above shows the Δn change region where the refractive index difference Δη between the waveguide core and the clad changes from Δη1 to Δη2 (Δηl> Δn2) along the light wave propagation direction. The present invention relates to an optical waveguide having a core whose cross-sectional shape does not change along the light wave propagation direction. In this case, the normalized frequency of the waveguide changes along the light wave propagation direction. On the other hand, as in the mode field diameter conversion circuit disclosed in the above-mentioned JP-A-6-43330, the refractive index of the core decreases and the core diameter increases as the distance from the end face increases. In this case, the normalized frequency of the waveguide or the optical fin is constant. As a result of preparing and examining various optical fibers having a constant normalized frequency, the above description regarding the optimal Δη distribution function form when the normalized frequency changes is based on the case where the normalized frequency is constant. I found that it was true. That is, if the length L of the refractive index change region is sufficiently long, for example, 3 mm or more, the coordinate of the Δη change region along the light wave propagation direction is defined as the X-axis under a constant condition. (X = 0 to L), X-Υ plot with Δη as the Y axis is expressed as Δη (Χ) = Δη1-(Δη1 one An2) x (XZL) In this case, excellent characteristics can be obtained in the kneading bond efficiency and deviation tolerance when 0.1 and ω <0.75, especially when ω = 0.2 to 0.33. It is not always necessary to take the above function form, and if these function forms are approximately obtained, it was possible to obtain a coupling efficiency and an allowable deviation value of excellent characteristics. X-Υ plot force with the X-axis as the coordinate of the Δη change area along the light wave propagation direction and the Υ-axis as Δη, and if convex downward, it is possible to obtain characteristics close to these optimal conditions. did it Even if it is not convex downward, the X-Υ plot with the X-axis (Χ = 0 ~) as the coordinates of the Δη change area along the light wave propagation direction and the Δ- (Χ) = Δ η 1 — (Δ η 1-Δ η 2) X (X / L) ° · ¹ and Δ η (Χ) = Δ η 1 - (Δ n 1 - Δ η 2) if X in a region surrounded by the curve represented by (XZL) ° ^{7 6,} excellent properties in binding efficiency and misalignment tolerance of the connection is obtained. The above-described optical waveguide or optical fiber can be manufactured, for example, based on the following description. The core of the quartz fiber is formed by a Ge dopant that increases the refractive index. By heating the quartz fiber, the dopant Ge is diffused, and the refractive index distribution changes. Since the diffusion coefficient of G e depends on the temperature, a temperature gradient is set so that the temperature of the fiber increases as it approaches the tip of the fiber, so that it approaches the end face of the fiber. An optical waveguide with a larger mode field diameter is fabricated. In order to set a desired refractive index distribution in quartz, it is necessary to appropriately set the temperature distribution of the fiber when heating the fiber. The temperature distribution of the fiber is controlled by a combination of a local cooling device or a heating device of the fiber. For example, in an electric furnace equipped with a cooling gas blowing nozzle, the fiber is locally cooled by the cooling gas from the blowing nozzle while heating the fiber with the electric furnace. By increasing the number of blower nozzles installed, finer local control of the refractive index becomes possible. The amount of air blown and the angle at which the gas is blown onto the fiber are also parameters for forming the refractive index distribution.

 By applying the mode-field diameter conversion optical waveguide fabricated as described above to an optical switch that switches the optical path of an input optical signal, it is possible to utilize its effectiveness. it can. By including two or more optical waveguides of the present invention, and by using the end face portion where the two optical waveguides abut against each other as the waveguide of the present invention, it is possible to improve the tolerance while suppressing a decrease in coupling efficiency and to improve the conductivity. The positioning accuracy of the wave path can be reduced.

The optical path switching switch is, for example, as follows. Light path switching 構成 The components of the switch are mounted on a plurality of cantilever beams, at least one cantilever beam, which are formed on a silicon substrate and are parallel to each other and connected by connecting members. An optical waveguide formed, a plurality of optical waveguides fixed to face the optical waveguide, and switch driving means for deforming the cantilever, comprising: an optical waveguide formed on the cantilever; Both of the fixed optical waveguides are the optical waveguides.

 As a switch driving means for deforming the cantilever, an actuator using a combination of a permanent magnet, a coil and a magnetic material is generally considered to be a force, which can be used for driving an optical switch. Other suitable actuators include an actuator combining a magnetic material on a cantilever and a movable permanent magnet disposed outside the optical switch, and an actuator utilizing electrostatic force. , Actuators that use the piezo effect, or actuators that use deformation of the shape memory alloy bimetal due to temperature changes, etc., as long as they can generate the necessary force to switch the optical switch. Can be used.

The optical waveguide or optical fiber of the present invention can be used as follows. When connecting the optical fiber and the optical waveguide of the present invention, the gap between the end faces in the connecting city can be increased. For example, when comparing under the same diffraction loss, if the mode field diameter is doubled, the gap between the end faces can be expanded four times. Optical waveguide circuits often include a polarizing element or a wavelength selection filter in the circuit. In such a case, the thickness of the optical element to be inserted is restricted by the ordinary waveguide, but this restriction can be alleviated by using the mode field diameter conversion waveguide. . Optical elements to be inserted include a polarizing element and a wavelength selection filter, but are not particularly limited thereto. The optical waveguide or optical fiber of the present invention may be used as follows. Since the mode diameter at the emission end of the laser diode, which is a light source for 1.3 m wavelength light, and the mode diameter of the single-mode waveguide optical fiber for 1.3 zm light are different, the laser diode When optical fibers are directly connected, radiation loss occurs due to the difference in their core diameters. Here, the mode diameter conversion optical waveguide of the present invention is inserted between the laser diode and the optical fiber, and the mode diameter of the waveguide at the laser diode side end face of the optical waveguide is the same as that of the laser diode. Radiation loss can be greatly reduced if the mode diameter is the same as the mode diameter and the mode diameter at the optical fiber side end face of the optical waveguide matches the mode diameter of the optical fiber. .

 By controlling the refractive index distribution near the exit end of the optical waveguide, it is possible to control not only the mode field diameter but also the width of the exit light exiting from the optical waveguide and the re-angle. Conventional optical devices including optical waveguides require lenses to control the beam divergence angle. On the other hand, the optical waveguide of the present invention can control the divergence angle of the outgoing beam, eliminating the need to mount a lens and simplifying the manufacturing process. It also has the advantage of eliminating reflection losses from the lens surface. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a distribution function of a refractive index difference m n between a core and a cladding of an optical waveguide according to the present invention. The horizontal axis is the coordinates (unit: mm) of the waveguide along the light wave traveling direction. Δn at the end of the waveguide (X = 10 mm) is Δn2 = 0.0006.

 FIG. 2 is a layout diagram of the deviation tolerance measurement.

FIG. 3 is a plot of the coupling efficiency deviation tolerance of the waveguide according to the present invention. It is. Δη at the coupling surface of the waveguide is equal to 0.02. FIG. 4 is a plot of the coupling efficiency deviation tolerance of the waveguide according to the present invention. Δη at the coupling surface of the waveguide is Δη 2 = 0.009. FIG. 5 is a plot of the coupling efficiency deviation allowable value of the waveguide according to the present invention. Δ η at the coupling surface of the waveguide is m η 2 = 0.0012. FIG. 6 is a plot of the coupling efficiency and the beam diameter expansion rate of the waveguide according to the present invention.

 FIG. 7 is a schematic diagram of a refractive index distribution forming device.

 FIG. 8 is a schematic view of an apparatus for forming a refractive index distribution optical fiber.

 FIG. 9 is a perspective view of one embodiment of a waveguide type two-circuit one-two optical switch according to the present invention.

 FIG. 10 is a top view of the waveguide-type two-circuit 1 × 2 optical switch shown in FIG.

 FIG. 11 is a detailed view of the waveguide-type two-circuit 1 × 2 optical switch shown in FIG.

 FIG. 12 is a schematic view of one embodiment of the optical input / output device according to the present invention. FIG. 13 is a schematic view of an embodiment of an optical waveguide with an optical element according to the present invention.

 FIG. 14 is a schematic view of one embodiment of the optical input / output device according to the present invention. FIG. 15 is a schematic diagram of one embodiment of a waveguide connection mode according to the present invention. FIG. 16 is a schematic diagram of one embodiment of a 1-shaped optical switch according to the present invention. is there.

 Hereinafter, reference numerals used in FIGS. 1 to 14 will be described.

1, 1 '·' · Δη = Δη2 end face, 2, 2 '... Δη = Δη1 end face, 3, 3' ... core, 4, 4 '... mode field, 5 … Axis shift amount, 1 1 ··· Al Gonion laser, 12… laser beam, 13… beam splitter, 14, 15, 16, 17… mirror, 18… moving stage, 19… sample support, 20, 2 1… Lens, 2 2… Sample, 3 1… Electric furnace, 3 2… Blast nozzle, 3 3… Optical fiber, 3 4… Fibre insertion length, 4 1… Optical fiber, 4 2… Movable optical waveguide, 4 3… cantilever, 4 4… silicon substrate, 4 5… magnetic film, 4 6… coil electrode, 4 7… thin-film electromagnet, 4 8… fixed optical waveguide, 4 9 ... connecting member, 50 ... light input end, 51, 5 ... positioned cantilever, 53 ... end face of movable optical waveguide 42 a, 54 ... end face of fixed optical waveguide 48 a , 55: Mode field for propagating light, 61: Quartz substrate, 62: Laser diode, 63: Hole for installing laser diode, 64: Photo diode, 6 5… Photo diode installation 6 6… Waveguide Δ η-constant area, 6 7… Waveguide Δ η change area, 6 8… Waveguide end face, 6 9… Optical fiber fixing groove, 70… Optical fiber , 71: Optical fiber core, 72, 73: Mode field, 81: Silicon substrate, 82: Polymer layer, 83: Width micro Groove, 84, 85 ... waveguide, 86 ... wavelength selection filter, 87 ... mode field, 91 ... quartz substrate, 92 ... laser diode, 93 ... Hole for installing laser diode, 94: Δη-constant region of waveguide, 95: Δη change region of waveguide, 96: waveguide end face, 97: mode field, 98 … Optical fiber fixing groove, 9 9… Optical fiber, 100… Optical fiber core, 101-Δ η control optical waveguide core, 102-Δ η control optical waveguide Δ η-constant region, 103 to Δ η control optical waveguide refractive index change region, 10 4 — Waveguide end face of Δ η control optical waveguide, 105: Mode field of propagating light, waveguide with constant core diameter of 8 m at 106-Δη = 0.045, A waveguide with a constant core diameter when 1 0 7 ... n = 0.09, a waveguide with a constant core diameter when 1 0 8 '' , 1 1 0… waveguide End face, 1x4 optical switch substrate, 1x4 optical switch substrate, 1x2 ... core of optical waveguide, 1x2 ... mode field, 1x2 ... thickness of 0.2 μππ Chromium electrode pattern, 125: Waveguide for introducing light to optical switch substrate 121, 126: Output optical fiber for guiding output from optical switch substrate 121 Iba. BEST MODE FOR CARRYING OUT THE INVENTION

 Next, an embodiment of an optical waveguide and an optical device according to the present invention will be described with reference to FIGS. 1 to 18.

 (Example 1)

 A 3-inch diameter silicon wafer whose surface is a silicon oxide layer is provided on a silicon wafer, which is a precursor of the polyimide represented by the structural formula (1) ((-0.84). A 1% by weight solution of amic acid in dimethyl acetate amide was applied by spin coating, and then applied at 100 ° C for 1 hour and then at 350 ° C for 30 minutes. Then, a lower cladding (film thickness: 20 / rn) was formed. Subsequently, on the surface of the lower cladding, in order to prevent the electron beam from being shaken by the charge-up during the irradiation of the electron beam, the surface of the fluorine-containing polyimide film is formed. Aluminum was deposited to a thickness of about 10 nm. The fluorinated polyimide film was irradiated with an electron beam, the refractive index of the irradiated portion was increased, and a waveguide was drawn. The acceleration energy of the electron beam is 25 keV, the irradiation width is 8 tm, and the length is

 A waveguide with a linear pattern of 100 mm was drawn.

In electron beam lithography, the refractive index increases according to the amount of electron irradiation. Therefore, by changing the electron irradiation amount along the light wave propagation direction, Δn can be modulated along the light wave propagation direction. The electron irradiation electron quantity was controlled as follows. The sample is set on a stage that can move in two axial directions perpendicular to the electron beam and perpendicular to each other. Electron beam current The irradiation time of the electron beam to the fluorinated polyimide film, that is, the amount of electron irradiation, was controlled by setting the constant and changing the moving speed of the stage.

First, the amount of electron irradiation was controlled so as to obtain the Δη distribution shown by f in FIG. The X-axis in Fig. 1 is the coordinates (unit: thigh) of the waveguide along the light wave traveling direction. The range from the starting point of the waveguide (X = Omm) to X = 4.6 mm is Δη—constant domain, and Δη = 0.045. From X = 4.6 mm to the end (χ = 10 mm), it is the Δη reduction region. At Χ = 10 mm, Δη = 0.006. When the difference between the starting point of Δ η decrease (X = 4.6 mm) and the X-coordinate of the waveguide is Δ Χ (= Χ—4.6), the decrease in the refractive index in the Δ η decreasing region is Δ X . · The distribution of mu η in the Δ η change region was set so as to be proportional to ² . That is, for X = 4.6 to l0.0 mm, Δ η (Χ) = 1.50 4 5-(1.5 0 4 5-1.5 0 6) Χ ((Χ-4. 6) /5.4) ⁰ · ² . The moving speed of the sample stage was set so as to obtain such a waveguide having a △ η distribution, and the waveguide was drawn with an electron beam.

 After drawing the waveguide, the aluminum layer on the drawn fluorinated polyimide film is removed with an etching solution, washed with water, and heated on a hot plate of 100 ° C. for 2 minutes. The polyimide film was dried. Next, a polyamic acid, which is a precursor of the polyimide represented by the structural formula (1) (X = 0.84), is applied by a spin coating method, and heated. It was imidized to form the upper cladding. The end face was cut out to form the input / output end, and the waveguide of Example 1f was manufactured.

Similarly, two waveguides each having the Δn distribution shown in a to h of FIG. 1 were produced (Examples 1a to lh, respectively). Table 1 shows the respective refractive index distributions. Table 1

Example 1 The function form (X is the horizontal axis of the waveguide) of the refractive index distribution Δ η (Χ) in a to y is expressed as Δ η = Δ η 1 — (A n 1 -Δ n 2) * [(X- ) / L] "ω

 Also, by changing the length of the refractive index decreasing region, waveguides of the refractive index distribution shown in Tables 1i to y were produced (Examples 1i to ly, respectively).

The deviation tolerance and the coupling efficiency are defined below. End faces of two waveguides In addition, light is propagated from one waveguide to the other waveguide, and the transmitted light intensity is measured. When the output light intensity is measured while displacing one waveguide in the vertical direction with respect to the waveguide, the difference between the position where the maximum output light intensity is given and the position where the lZe output intensity is given is the deviation tolerance. I do. In addition, the maximum propagation light intensity when the waveguides are connected to each other with a constant Δη of Δη1 is set to 1, and an intensity ratio thereof to the coupling efficiency.

As shown in FIG. 2, two waveguides (Example If, If) having a Δη distribution shown by f in FIG. 1 are brought into contact with end faces 1 and 1 ′ having a small Δη as shown in FIG. Then, light was incident from the end face 2 and the waveguides 1 f and 1 f ′ were aligned so that the output from the end face 2 ′ was maximized. As a result, the coupling efficiency was 90%, and the allowable deviation was 17 μm. Similar measurements were performed for waveguides 1a to 1y. Fig. 3 shows a plot of the allowable coupling efficiency deviation for 1a to ly. As can be seen from FIG. 3, when the refractive index distribution function form Δη (X) is the same in the refractive index change region, the coupling efficiency and the deviation tolerance increase as the refractive index change region length L increases. If the length of the refractive index change region is fixed as a sufficiently long value, for example, 3 mm or more, the distribution of Δη becomes Δη (Χ) = 1.50545-(1.50545- 1.5 0 6) x ((X-a) / b) "(a: constant refractive index region length, b: refractive index change region length), and the coupling efficiency and deviation tolerance Ω is 0.1, ω, and 0.75 In particular, when ω = 0.2-0.33, the coupling efficiency is 90%, which is equivalent to that of the conventional waveguide. However, the deviation tolerance is three times as large as that of the conventional waveguide, and if these function forms are approximately obtained, the coupling efficiency and the deviation tolerance close to the above characteristics can be obtained. In addition, if the X-Υ plot with the coordinates of the Δη change area along the light wave propagation direction as the X-axis and Δη as the Υ-axis becomes convex downward, characteristics close to the optimum conditions can be obtained. In addition, the Δ η change along the lightwave propagation direction was obtained. PT / JP97 / 02047

The X—Y plot, where the coordinates of the quaternization region are the X axis (X = 0) and the n axis is the Y axis, yields the following equation: η η (Χ) = Δ η 1 — (Δ η ΐ — A n 2) A curve represented by x (X / L) ^{0 1} and a curve represented by mm η (Χ) = Δ η 1 — (Δ η 1 — A n 2) x (XZ L) ^{0 7 &} If it is in the region enclosed by the symbols, excellent characteristics can be obtained in connection coupling efficiency and deviation tolerance.

 (Example 2)

In the same manner as in Example 1, an optical waveguide in which Δη changes along the light wave propagation direction was manufactured. Table 2 summarizes the refractive index distributions of the fabricated waveguides (Examples 2a to 2y).

Table 2

Example 2 The function form (X is the horizontal axis of the waveguide) of the refractive index distribution Δ η (Χ) in a to y is expressed as Δ η = Δ η 1 — (Δ η 1-An 2) * [(X- ) / L] 'ω

Δ η — In the constant region, Δ η = 0.004 45, and in the Δ η decreasing region, Δ η decreases. At the end of the waveguide (X = 10 mm), Δ η = 0.00 0 9 is obtained. In the same manner as in Example 1, the coupling efficiencies of the waveguides of Examples 2a to 2y and the allowable deviation were measured. Fig. 4 shows a plot of the allowable coupling efficiency deviation for 2a to 2y. As can be seen from FIG. 4, when the refractive index distribution function type Δη (Χ) in the refractive index change region is the same, the longer the refractive index change region length L, the higher the coupling efficiency and the allowable deviation. If the length of the refractive index change region is fixed at a sufficiently long value, for example, 3 mm or more, the distribution of Δη becomes

△ η (Χ) = 1.5 0 4 5 — (1.5 0 4 5-1.5 0 9) x ((X-Μ)

/ L) ^u (M: constant refractive index region length, L: refractive index change region length), ω for optimizing coupling efficiency and deviation tolerance is 0.1 <ω <0.75. It is. In particular, when ω = 0.2, the coupling efficiency is 97% of the conventional waveguide, which is almost the same, but the allowable deviation is improved to 2.5 times that of the conventional waveguide. Moreover, if these function forms were approximately obtained, it was possible to obtain the coupling efficiency and the allowable deviation value close to the above characteristics. Furthermore, along the light wave propagation direction

If the Χ- Υ plot, in which the coordinates of the change area are the X axis and is the Υ axis, are convex downward, characteristics close to the optimal conditions could be obtained. In particular, even if the projection does not become downward, the coordinate of the Δ η change area along the light wave propagation direction is the X axis (Χ = 0 to), and the Δ η is the X axis. η (Χ) = um nl one (Δ η 1-Δ η 2) X (X / L) ° · ¹ and Δ η (Χ) = um η 1-(Δ η 1-Δ η 2 ) if a region surrounded by the X (XZL) curve expressed by ° ^{7 5,} excellent properties in binding efficiency and misalignment tolerance of SeMMitsuru is obtained.

 (Example 3)

In the same manner as in Example 1, an optical waveguide in which Δη changes along the light wave propagation direction was manufactured. Table 3 summarizes the refractive index distributions of the fabricated waveguides (Examples 3a to 3y). Table 3

Example 3 The function form (X is the horizontal axis of the waveguide) of the refractive index distribution Δ η (Χ) in a to y is defined as Δ η = Δ η 1-(Δ n 1 -A n 2) * [(X- M) / L] "where ω is the parameter in each waveguide

Δ η — In the constant region, Δ η = 0.004 45, An decreases in the Δ η decreasing region, and Δ n = 0 · 0 at the end of the waveguide (X = 10 mm). 0 1 2 is obtained. In the same manner as in Example 1, the coupling efficiencies of the waveguides of Examples 3a to 3y and the allowable deviation were measured. Fig. 5 shows a plot of the allowable coupling efficiency deviation for 3a to 3y. As can be seen from FIG. 5, when the refractive index distribution function form Δη (X) in the refractive index change region is the same, the longer the refractive index change region length L, the higher the coupling efficiency and the allowable deviation. If the length of the refractive index change region is fixed at a sufficiently long value, for example, 3 mm or more, the distribution of Δ η is calculated as follows: m η (Χ) = 1.50 4 5 — (1.50 4 5 — 1. 5 0 1 2) X ((X-Μ)

L) "(Μ: constant refractive index region length, L: refractive index change region length), ω for optimizing the coupling efficiency and deviation tolerance is 0.1 <ω <0.75. In particular, when ω = 0.2, the coupling efficiency is 98% of the conventional waveguide, which is almost the same, but the deviation tolerance is improved to twice that of the conventional waveguide. Also, if these function forms were approximately obtained, it was possible to obtain coupling efficiency and deviation tolerance close to the above characteristics, and furthermore, it was possible to obtain the coordinates of the Δη change region along the light wave propagation direction. If the X-Υ plot, where X is the X-axis and Δ η is the Υ-axis, is convex downward, it is possible to obtain characteristics close to the optimal conditions, especially if it is not convex downward. X-Υblot ^, Δη (X) = Δη1 一, where the X-axis (Χ = 0〜) is the coordinate of the Δη change area along the light wave propagation direction, and the Δ-axis is the Υ-axis. Δ η 1-mm n 2) x (XZ L). Is the curve and厶η (Χ) = Δ η 1 - (Δ η 1 one Δ η 2) x (XX L ) 0 - If a region surrounded by the curve represented by ^76, connection coupling efficiency Also, excellent characteristics in tolerance of deviation can be obtained.

FIG. 6 shows the beam diameter in the region where Δ η is Δ η （(where the maximum electric field intensity at the center of the beam is 1 when the electric field intensity is e ^2). twice) radius d,, delta n is your Keru beam diameter delta n 2 area are d _2, the beam magnification in the d ₂ / d]厶to come to defined and n is delta n 2 Coupling efficiency and beam expansion ratio when connecting certain end faces Here is a plot of By optimizing ω in the waveguide of the present invention, it is possible to achieve both a high connection efficiency and an enlarged beam diameter as shown by the hatched area in FIG.

 (Example 4)

Using a mixture of poly (methyl methacrylate) (Ρ デ イ) as the clad and a mixed system of ΡΜΜΑ and disperse red 1 (DR 1) as the core, the core is formed by resist coating and etching. By patterning, an optical waveguide having a length of 100 and a core shape of 8 × 8 m ² was formed. The DR1 content was adjusted so that the refractive index of the core 1 was higher by 0.045 (about 0.3%) than the refractive index of the clad.

 By irradiating the core with a laser beam, the refractive index of the core is reduced. Since the width of decrease in the refractive index depends on the amount of laser beam irradiation, a change in the irradiation time can form a refractive index distribution in the light propagation direction of the waveguide. The waveguide was irradiated with laser light using the laser light irradiation device shown in FIG. 7 to form a refractive index distribution in the light wave propagation direction.

 The irradiation light is light 12 having a wavelength of 4888 nm of the argon ion laser 11. The laser beam was bisected by the half mirror 13, and the waveguide 22 was irradiated with light from above and below using the mirrors 16 and 17. The waveguide 22 was fixed to a sample holder 19 attached to a sample table 18 driven by a stepping motor. The sample stage moves in one horizontal axis, but the moving direction of the sample stage and the direction of the linear pattern of the core are matched so that the linear pattern of the core does not deviate from within the laser beam when the sample stage moves. It is necessary.

The laser beam irradiation amount was controlled so as to obtain the same Δη distribution as in Example 1f. From the starting point of the waveguide (X = 0mni) to X = 4.6mni, Δη-constant region, and Δη-0.0045. From X = 4.6 mm, the end (X = Up to 10 mm), the area is reduced by n, and when X = 10 mm, A n = 0.006. Assuming that the difference between the starting point of decrease of n (X = 4.6 mm) and the X wing of the waveguide is mu X (= X—4.6), the decrease in the refractive index in the Δη decrease region is mu X. · The distribution of mu η in the Δ η change region was set so as to be proportional to ² . That is, at Χ = 4.6 to 10.0 mm, Δ η (Χ) = 1.5 0 4 5-(1.5 0 4 5-1.500 6) Χ ((Χ-4. 6) / 5.4) ⁰ · ² The moving speed of the sample stage was set so as to obtain such a waveguide having a Δη distribution. An end face was cut out to form an input / output end, and a waveguide was obtained (Example 4). By covering the outer wall of the waveguide except for the input and output end faces with black clay and shielding the light, visible light was absorbed and the refractive index of the core was prevented from changing. Similarly, waveguides having the same Δη distribution as those of Examples 1a to h were produced (Examples 4a to 4h, respectively).

In the same manner as in Example 1f, the allowable deviation and the coupling efficiency of Example 4f were measured. As a result, the deviation tolerance was 16 m, and the coupling efficiency was 90%, which almost coincides with the result of Example 1f. The results of the waveguides of Examples 4a to 4h also substantially agreed with the results of the waveguides of Examples 1a to 1h, respectively. In an optical waveguide in which the color content of the core changes along the light wave propagation direction, the refractive index is the same as in the optical waveguide in which the fluorine content changes along the light wave propagation direction as in Example 1. In the case where the refractive index distribution function form Δ η () in the change region is the same, as the refractive index change region length L becomes longer, the coupling efficiency and the allowable deviation value improve, and the refractive index change region length becomes, for example, When fixed at a sufficiently long value, such as 3 mm or more, the distribution of Δη becomes Δη (Χ) = 1.50545— (1.5054.5-1.5012) X ((X-) / L) ^ω (Μ: constant refractive index region length, L: refractive index change region length), ω that optimizes coupling efficiency and deviation tolerance is 0.1 < ω <0.75. In particular, as described above, ω = 0.2 ~ In the case of 0.33, excellent values are obtained for both the coupling efficiency and the allowable deviation. Also, if these function forms are approximately obtained, it is possible to obtain a coupling efficiency and an allowable deviation value close to the above characteristics. Furthermore, if the X-Y plot with the X-axis as the coordinate of the Δn change area along the light wave propagation direction and the Y-axis as Δη is convex downward, the characteristics close to the optimal conditions will be obtained. I got it. Even if it is not convex downward, the X-— plot with the X-axis (Χ = 0 0) as the coordinates of the Δη change area along the light wave propagation direction and the Δ-axis as η (Χ) = Δ η 1 — (Δ η 1 one Δ η 2) x (X / L) ° · ¹ and a curve Δ η (Χ) = Δ η 1-(Δ η 1 one D n 2) In the region enclosed by the curve represented by x (XZL) ° ⁷⁵ , excellent characteristics can be obtained in connection coupling efficiency and deviation tolerance.

 (Example 5)

Click La head of refractive index 1.4 3 quartz core is a silica glass doped with G e 0 _2, Δ η 0.0 4 3, the light-off § core diameter of 8 mu Iotaita 8 It was inserted into an electric furnace 31 shown in the figure, and a temperature gradient was applied to the tip of the fiber 33. By heating the optical fiber 33, the dopant Ge is diffused, and the refractive index distribution changes. Since the diffusion coefficient of Ge depends on the temperature, an appropriate temperature gradient is applied to the fiber to produce an optical waveguide whose mode field diameter increases as it approaches the end face. The electric furnace 31 is provided with a cooling gas blow nozzle 32. The angle of this nozzle is adjustable, and the angle of air blow to the fiber can be adjusted. Using the temperature of the electric furnace 31, the angle of the blow nozzle 32, the blow volume, and the insertion length 34 of the fiber as setting parameters, a desired temperature distribution can be formed in the fiber, and the refractive index distribution can be designed. it can. In this way, the optical fiber was heated to produce a number of mode-converted optical fibers. From the optical fibers, optical fibers having the same function form of Δη distribution as those in Examples 1a to 1h were selected (Examples 5a to 5h). Example In the same manner as in 1, the deviation tolerance and the coupling efficiency were measured. As a result, the deviation tolerance and the coupling efficiency were almost the same as the result of Example 1. In the present embodiment, not only the Δn becomes smaller but also the core diameter becomes larger as it approaches the fiber end face. As a result, unlike the first embodiment, the normalized frequency of the fiber is kept constant along the light wave propagation direction. However, also in this case, as in the case of Embodiment 1, when the refractive index distribution function form △ n (X) in the refractive index change region is the same, the longer the refractive index change region length L becomes, If the coupling efficiency and deviation tolerance are improved and the length of the refractive index change region is fixed at a sufficiently long value, for example, 3 mm or more, the distribution of m n is expressed as m n (X) = 1. 5 0 4 5 — (1.50 4 5 — 1.500 6) X ((X—M) no L ”(: constant refractive index region length, L: refractive index change region length) In addition, it was found that ω that optimizes the coupling efficiency and deviation tolerance is 0.1 <ω, which is 0.75 In particular, when ω = 0.2, the conventional derivation is obtained. Although the coupling efficiency is 90%, which is almost the same as that of the waveguide, it is found that the tolerance for deviation is improved by three times. Coupling efficiency and The X-Υ plot with the X-axis as the coordinate of the Δ η change region along the light wave propagation direction and the Υ-axis as Δ η is projected downward. In this case, it was possible to obtain characteristics close to the optimum conditions.Especially, the coordinates of the Δη change area along the light wave propagation direction were set on the X axis (Χ = 0−) and Δ The X—Υ plot with η as the Υ axis is defined as Δ η (Χ) = m nl one (Δ η l-An 2) X (X / L) ^0- ' Χ) = Δ η 1-(Δ n 1-Δ n 2) x (XZ L) In the area surrounded by the curve represented by ^{6 '75} , excellent characteristics in connection coupling efficiency and deviation tolerance are obtained. I know what you can get.

(Example 6) FIG. 9 is a perspective view of one embodiment of a waveguide type two-circuit 1 × 2 optical switch according to the present invention. 41 is an optical fiber, 42 is a movable optical waveguide, 43 is a cantilever, 44 is a silicon substrate, 45 is a magnetic film, 46 is a coil electrode, and 47 is a thin-film electromagnet. Reference numeral 48 denotes a fixed optical waveguide. FIG. 10 is a top view of one embodiment of a waveguide type two circuit 1 × 2 optical switch according to the present invention. 42 a and 42 b are destructible optical waveguides, 46 a and 47 a are movable optical waveguides, and the coil electrodes and thin-film electromagnets on the 42 a side, and 46 b and 47 b are Coil electrodes and thin-film electromagnets on the movable optical waveguide 42b side, 48a, 48b, 48c and 49d are fixed optical waveguides, and 49a and 49b are optical input terminals. is there. The figure shows a state before the power is supplied to the optical switch. Light input from the light input terminals 50 a and 50 b is transmitted to the movable optical waveguide 42 formed on the cantilever 43. The ends of the cantilever beams 43 are connected by connecting members 49, and can be displaced in the plane of the silicon substrate while keeping them parallel to each other. A magnetic film 45 is formed on the connecting member 49. On the silicon substrate on both sides of the magnetic film 45, a thin film electromagnet 47 composed of a magnetic film, a permanent magnet and a thin film magnet is formed. Electric power is supplied to the thin electromagnet 47 from a power source (not shown) via the coil electrode 46. Turtle pressure can be set in the range of 3 to 10 volts. The optical waveguide is formed in the same manner as in Example 1 except that the fluorinated polyimide of the structural formula (1) (X = 0.84) is used as an upper clad and a lower clad. Made on a cantilever. The optical waveguide layer was manufactured by electron beam lithography.

When a current flows through the thin-film electromagnet 47 a in the direction in which the magnetic film 45 is strongly attracted, and when a current flows in the thin-film electromagnet 47 b in a direction in which the magnetic film 45 is weakly attracted, the cantilever beam 4 3 Is displaced as shown by the broken line 51, and the movable optical waveguide 42a becomes the fixed optical waveguide 48a and the movable optical waveguide 42b becomes the fixed optical waveguide. 4 Connected to 8c.

 Here, when the direction of the current flowing through the thin film electromagnets 47a and 47b is reversed, the magnitude relationship of the electromagnetic force generated between the thin film electromagnets 47a and 47b and the magnetic film 45 is reversed. Then, the cantilever beam 43 is displaced as shown by a broken line 52, and the movable optical waveguide 42a becomes the fixed optical waveguide 48b, and the movable optical waveguide 42b becomes the fixed optical waveguide 48Δ. Be closely related. This makes it possible to switch the optical path.

 In the state where the movable optical waveguide 42a and the fixed optical waveguide 48a are connected, an enlarged view of the connection portion between the emissive optical waveguide 42a and the fixed optical waveguide 48a is shown in FIG. Shown in the figure. Δη is gradually decreased toward the end face 53 of the annihilation type optical waveguide 4 2a, and the mode field diameter 55 of the propagating light is changed to the end face.

It was gradually expanded toward 53. Similarly, fixed optical waveguides

Δη was gradually decreased toward the end face 54 of 48 a. The length of the Δ η change region was set to 3.6 mm, and the distribution of Δ η in the Δ η change region

Same as 1 f. In this case, the allowable deviation is 17 μιη, and the coupling efficiency is 85%. Since the magnitude of the tolerance is about three times as large as that of the optical waveguide of the conventional method, the movable optical waveguide 42 a and the fixed type are used when the optical path is switched by an actuator. The allowable positioning accuracy of the optical waveguide 48a is approximately

Relaxed three times. It was possible to obtain an optical path switching optical switch whose optical loss characteristics were not easily affected by the deviation of the optical axis.

 (Example 7)

FIG. 12 is a schematic view of one embodiment of the optical input / output device according to the present invention. An optical waveguide was fabricated on a quartz substrate in the same manner as in Example 1f. At the time of electron beam writing, the moving speed of the moving stage in the refractive index change region 67 in the waveguide is increased toward the waveguide end face 68, and the moving stage is moved toward the waveguide end face 68. The waveguide was drawn so that the refractive index gradually decreased. The refractive index distribution function was made the same as in Example 1f so that the mode field diameter of the propagating light gradually increased toward the waveguide end face. A hole 63 for installing a laser diode and a hole 65 for installing a photo diode were provided on the substrate 61, and a laser diode 62 and a photo diode 64 were provided respectively. Further, an optical fiber fixing groove 69 was provided, and an optical fiber 70 having a core diameter of 8 μιη was fixed.

 The fixed optical fiber 70 is the same mode field diameter conversion optical waveguide as that of Example 5f. The coupling efficiency is about 90%, which is almost the same as when using an optical waveguide and an optical fiber with a constant Δη, but the allowable deviation is about three times that of the connection. An optical input / output device with a large tolerance was obtained.

 (Example 8)

FIG. 13 is a schematic view of an embodiment of an optical waveguide with an optical element according to the present invention. A mode-field diameter-converting optical waveguide was fabricated on a silicon substrate in the same manner as in Example 1f. The waveguide 8 of Example 1f is sandwiched between the grooves 83 of the radiation 75 formed by the dicing source so that the end face of the waveguide facing the groove has a low Δη. 4 and 85 were prepared. A wavelength selection filter 86 having a width of 747 microns and transmitting only light having a wavelength of 1.3 m was inserted into the groove 83. When a light with a wavelength of 1.3 μιη was introduced into this optical waveguide with an optical element and the transmission loss was measured, the loss was reduced to about 14 compared to the case of a normal Δη-constant optical waveguide. It turned out to be. As described above, by applying the mode field diameter conversion waveguide of the present invention to an optical device in which an optical element is inserted into a waveguide, transmission loss can be reduced. . (Example 9)

 FIG. 14 is a schematic view of one embodiment of the optical input / output device according to the present invention. An optical waveguide was fabricated on a quartz substrate in the same manner as in Example 2d. At the time of electron beam writing, in the refractive index change region 95 of the waveguide, the moving speed of the destroying stage is increased toward the waveguide end surface 96, and the refractive index gradually increases toward the waveguide end surface 96. The waveguide is drawn so as to be reduced to a lower value, and the mode field diameter 97 of the propagating light is made to gradually expand toward the waveguide end face 96. At this time, a waveguide different from waveguide 2 d in the following three points was manufactured. i) The waveguide width is. ii) Δη of the waveguide 94 is 0.090, Δη decreases in the refractive index change region 95, and Δη is 0.0 at the waveguide end surface 96. 0 1 8 iii) The refractive index modulation region length 95 is 5.4 mm, and the function form of Δη in this region is as follows: The coordinate of the Δη change region 95 along the light wave propagation direction is the X axis (X = 0 to 5.4 mm), and the X—Y plot with Δn as the Y axis is Δ η (Χ) = 0.0 0 9 0—

(0. 0 0 9 0 - 0. 0 0 1 8) X (X / L) ° - 5 in the lower subsidiary in earthenware pots by expressed and.

 A hole 93 for setting a laser diode was provided on the substrate 91, and a laser diode 92 having an oscillation wavelength of 1.3 μιη was set. The output beam diameter of the laser diode is 4 μπι. Further, an optical fiber fixing groove 98 was provided, and an optical fiber 98 having a core diameter of 8 μπι was fixed.

 The intensity of the light emitted from the optical fiber 98 in this apparatus was 85% of the light emitted from the laser diode 92. Laser diode 92 and optical fiber

When 9 and 8 are directly connected, radiation loss occurs due to the difference in their core diameters. In this device, the mode diameters are almost equal between the laser diode 92 and the waveguide 94 and between the optical fiber 99 and the waveguide 95. Radiation loss was significantly reduced.

 (Example 10)

FIG. 15 is a schematic view of one embodiment of a waveguide connection mode according to the present invention. The core 101 of the optical waveguide was manufactured by electron beam lithography in the same manner as in Example 1f. When drawing the refractive index change region 103 in the waveguide, the moving speed of the moving stage is increased toward the waveguide end face 104, and the refractive index is gradually decreased toward the waveguide end face 104. The waveguide core was drawn such that the diameter of the propagation light mode field 105 gradually increased toward the waveguide end face 104. At this time, a waveguide different from the waveguide 1f was fabricated in the following three points. i) The diameter of the core 101 shall be 46 m. ii) Δη of waveguide 101-Δη of constant region 102 is 0.0090, and Δη approaches waveguide end surface 104 in refractive index change region 103 , At the waveguide end face 104, Δη is set to 0.001 12. iii) The length 103 of the refractive index modulation region is 5.4 dragons, and the function type of Δη in this nod region is as follows: The coordinate of the Δη change region 103 along the light wave propagation direction is the X-axis. (X = 0 to 5.4 mm), the X—Y plot with Δη as the Y axis is Δη (Χ) = 0.0090— (0.00.090 — 0.00.01 8) X (X / 5.4 mm) ⁰ · ⁵

 The Δn control optical waveguide was connected to a Δn-constant waveguide 106 in which the core and the cladding were made of polyimide. Δη—In the constant waveguide 106, light having a wavelength of 1.3 μππ is guided in single mode, the core diameter is 8 / xm, and Δη is about 0.0045. is there.

As a comparative example, a waveguide having a core diameter of 4 μπι and a constant Δη of 0.1 μm and a constant waveguide diameter of 107 was produced. Δη—a constant core diameter of 8 μιη With the waveguide 108 of the first embodiment. Δη—In the constant waveguide 108, light with a wavelength of 1.3 μιη Single mode waveguide. The intensity of the light emitted from the waveguide end face 109 was 1.5 times that of the light emitted from the waveguide end face 110. When the high-mm waveguide 107 with a core diameter of 4 mm is directly connected to the waveguide 108 with a normal core diameter of 8 μπι, radiation loss occurs due to the difference in the core diameters. . In the connection mode of the present invention, since the mode diameters at the connection portions are almost equal, the radiation loss can be significantly reduced.

 (Example 11)

 FIG. 16 is a schematic view of one embodiment of the L-shaped 1 × 4 optical switch according to the present invention. The core 122 of the optical waveguide in the optical switch substrate 121 was produced by electron beam lithography in the same manner as in Example 1f. In FIG. 16, the input / output part of the switch where the diameter of the mode field 123 changes is the Δn control area, and Δn becomes smaller toward the end face. . The other part is the Δη-constant region. The waveguide fabricated here differs from waveguide 1f in the following three points. i) The diameter of the core 122 is 4 μηι. ii) Δη of the waveguide 122-Δη of the constant region is 0.090, and in the refractive index change region, the value of μη decreases as approaching the waveguide end face, and at the waveguide end face, Is to make the value of η equal to 0.0012. iii) Refractive index modulation The length of the region is 5.4 mm, and the function type of Δη in this region is as follows: The coordinates of the Δη change region 103 along the light wave propagation direction are represented by the X axis (X-0 to 5.4 mm ), And the X—Y plot with Δ η as the Y axis is Δ η (0) = 0.0 0 9 0—

(0.0 0 9 0 - 0. 0 0 1 8) X (X / 5.4mm) ° - and calluses on earthenware pots by represented by ^6.

A chrome electrode pattern 124 with a thickness of 0.2 μπι was formed on the ephemeral cladding of the optical waveguide by resist processing. An appropriate current is passed through the chrome electrode, and the heat generated at that time causes the refractive index of the waveguide below the chrome electrode to be reduced. Change and perform the switching operation of the optical path. In this way, a Y-shaped IX4 optical switch substrate was obtained.

 The above-mentioned Y-shaped optical switch substrate 121 is used as the output side light for guiding the output from the waveguide 125 that guides light to the optical switch substrate 121 and the optical switch substrate 121. Connected to fin. The optical fiber used here has a core diameter of 8 μιη, in which light with a wavelength of 1.3 βm is guided in single mode.

 By using a high Δη waveguide with a core diameter of 4 μπι as a 1Χ4 optical switch, the radius of curvature of the waveguide can be reduced, and a core diameter of 8 μιη The switch can be made more compact than when using the above waveguide. However, when connecting to an optical fiber with a core diameter of 8 m, radiation loss occurs due to the difference in those core diameters. In the optical switch of the present invention, the radiation loss is maintained by taking advantage of the use of the high Δη waveguide by matching the mode diameter at the connection portion with the optical fiber. Could be reduced.

 According to the present invention, the positioning accuracy in connection of an optical waveguide, an optical fiber, and the like can be relaxed. In addition, the gap between the end faces of the optical fiber and the junction of the optical waveguide could be enlarged. In a high-performance optical device, an optical function element such as a wavelength selection filter or a polarization element may be introduced into an optical transmission line such as an optical waveguide or an optical fiber. The restriction on the thickness of the optical element to be introduced was relaxed. In addition, since the mode field diameter can be converted with low loss, optical elements with different mode field diameters such as laser diodes and optical fibers can be converted to low loss. You can now connect with.

 (Example 12)

Polya, a precursor of fluorinated polyimide with the structure of the following chemical formula A varnish of midic acid was spin-coated on a quartz substrate 101, baked at about 350 ° C, and imidized.

The film thickness of the obtained sample 102 was about 2 Om. It is known that the refractive index of sample 102 increases when irradiated with an electron beam. Therefore, when the electron beam irradiated portion is patterned into the core shape of the optical waveguide, the optical waveguide can be drawn.

 FIG. 17 is a schematic view of a refractive index distribution forming device. The moving stage 107 of the refractive index distribution forming device drives the sample support 106. On the sample support 106, a sample 102 formed on a quartz substrate 101 is placed. The moving direction of the sample stage 106 is two axes (X, Y) directions perpendicular to each other, and can move on the XY plane perpendicular to the electron beam 104 from the electron beam source 103. The current of the electron beam 104 was set constant, the moving speed of the stage was changed, and the irradiation amount of the electron beam to the polymer was changed.

An optical waveguide was drawn by the following procedure. First, the moving stage is driven only in one axis direction (X axis), the electron beam current is 8 nA, and the electron beam scanning area (the electron beam irradiation area in the XY plane when the moving stage is fixed) is 4 times. The optical waveguide 1 13 was drawn as X 4 μm ² . The sample was introduced into the Kameko beam from the end face 108 side, and the stage was driven at a constant speed until the point 110 shown by the broken line in Fig. 4. 0 9 was moved until it passed the electron beam. Next, after moving the stage in the direction perpendicular to the optical waveguides 113 using the Y-axis moving stage, the electron beam scanning area is set to 8 X 8 μιη ^2, and this time the moving stage Was moved rightward in FIG. 4, an optical waveguide was introduced into the electron beam from the end face 109 side, and an optical waveguide 114 was drawn. In this case, the moving speed was kept constant.

 By repeating the above process once again, the optical waveguides 115 and 116 were drawn, and as a result, four optical waveguides were drawn. Polyamide acid, a precursor of the same polyimide, was spin-coated on the drawn film, baked at 350 ° C., and imidized.

 Fig. 18 shows the distribution of the mode field of the optical waveguide observed by cutting out the end faces 108 and 109 and then introducing light into the four optical waveguides from the end face 108. FIG. The optical waveguides 113 and 115 with the mode fields gradually expanded and the optical waveguides I 14 and 116 with a constant mode field could be formed on the same substrate. Industrial applicability

 An accurate optical axis alignment can be achieved without using a lens in the optical coupling system for laser diodes, photo diodes, optical waveguides, optical fibers, etc., so that an optical module can be provided at low cost. There are also applications in gigabit-class high-speed optical communication networks in addition to home optical communication networks.

Claims

The scope of the claims

 1. In an optical waveguide whose mode field diameter increases or decreases at the input / output end, the optical waveguide is made of a polymer, and the core of the core in the optical waveguide cross-section perpendicular to the light wave propagation direction. An optical waveguide, wherein the size is constant irrespective of the position of the optical waveguide, and the difference in refractive index between the core and the clad changes along the light wave propagation direction.

 2. In an optical waveguide where the mode field diameter increases or decreases at the input / output end,

 The optical waveguide is made of a polymer,

 The size of the core in the cross section of the optical waveguide perpendicular to the light wave propagation direction is constant regardless of the location of the optical waveguide,

 The refractive index of the cladding is constant,

 The refractive index of the core changes along the light wave propagation direction

An optical waveguide characterized by this.

 3. In the optical waveguide according to claim 1 or claim 2,

 The core force is composed of a polymer in which a pigment that increases the refractive index of the core when mixed with the polymer is dispersed or bonded,

 An optical waveguide, wherein the dye content of the core changes along a light wave propagation direction.

 4. The method for manufacturing an optical waveguide according to claim 3,

 Controlling the amount of light irradiation on the core to form a refractive index distribution in the light wave propagation direction of the core;

A method for manufacturing an optical waveguide, comprising:

5. In an optical waveguide where the mode field diameter increases or decreases at the input / output end, The optical waveguide is made of a fluorinated polymer,

 The fluorine content of the light wave propagation portion of the optical waveguide changes along the light wave propagation direction

An optical waveguide characterized by this.

 6. The optical waveguide according to claim 5, wherein a size of a core in a cross section of the optical waveguide perpendicular to a light wave propagation direction is constant irrespective of a position of the optical waveguide.

 7. The optical waveguide according to claim 5 or claim 6, wherein

The fluorinated polymer is a _polymer obtained by introducing a polymer represented by the above chemical formula into the _polymer by substituting 1 C „F _{2 mt} (m = 1 to 5) into the polymer. An optical waveguide, comprising:

 8. The method for manufacturing an optical waveguide according to claim 5, claim 6, or claim 7, wherein:

 The electron irradiation increases the refractive index of the fluorinated polymer,

 By changing the amount of irradiated electrons in the light wave propagation direction,

 The refractive index of the electron beam irradiated part changes in the light wave propagation direction

A method for manufacturing an optical waveguide, comprising:

9. The method for manufacturing an optical waveguide according to claim 8, wherein the energy of the irradiated electron beam and the irradiation width of the electron beam are constant in the light wave propagation direction of the optical waveguide.

 10. In the method for manufacturing an optical waveguide according to claim 8 or claim 9, the electron beam is irradiated such that the irradiation density of the electron beam inside the film is higher than that on the surface of the polyimide thin film. Irradiate,

 Guides light inside the polyimide film

A method for manufacturing an optical waveguide, comprising:

 11 1. The optical waveguide according to any one of claims 1, 2, 3, 5, 6, and 7,

 An optical waveguide characterized in that the contours of the refractive index distribution in the cross section of the optical waveguide consist only of convex curves.

 1 2. Along the light wave propagation direction, the ηη change region where the refractive index difference Δη between the waveguide core and the clad changes from Δηΐ to Δη2 (Δη1> ηη2) The purpose is to change the mode diameter of the propagating light in the Δη change region by having it, and the cross-sectional shape of the core does not change along the light wave propagation direction. In an optical waveguide for guided wave,

 An optical waveguide characterized in that an X-Υ plot, in which the coordinate of the mu η change region along the light wave propagation direction is the X-axis and Δ η is the Υ-axis, is convex downward.

 13. Along the light wave propagation direction, there is a Δη change region where the refractive index difference μη between the waveguide core and the cladding changes from μ nl to Δη2 (Δη1> Δη2). In this way, the purpose is to change the mode diameter of the propagating light in the Δη change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. In an optical waveguide for waves,

The beam diameter in the region where Δη is Δη1 When the value is 1, the electric field strength becomes e- ² , twice the beam radius). In the region where n is Δη 2, the beam diameter is defined as d ₂ , and the beam expansion ratio dz / d, as κ, and the two waveguides are connected by the end faces where Δ η = Δ η 2. When the coupling efficiency is defined as 7 ?, the coupling efficiency and the beam expansion rate are

 /?> One 0.05 X (K-1) + 1 and / c> 1.2

An optical waveguide characterized by satisfying the following.

 1 4. There is a Δη change region where the refractive index difference Δη between the waveguide core and the cladding changes from Δηΐ to Δη2 (Δη1> Δη2) along the light wave propagation direction. In this way, the purpose is to change the mode diameter of the propagating light in the Δη change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. In an optical waveguide for waves,

The X-Y plot with the X-axis (X = 0 to L) as the coordinates of the Δη change area along the light wave propagation direction and the Y-axis as Δn is given by η η (Χ) = Δ η 1 — (A n 1 one Δ η 2) X (X / L) °- ^! and n (X) = m n 1-(Δ n 1-Δ n 2) x (X / L) ° ^-75 An optical waveguide characterized by being in a region surrounded by a curve represented by:

 15. There is a Δη change region where the refractive index difference Δη between the waveguide core and the cladding changes from Δηΐ to Δη2 (Δη1> Δη2) along the light wave propagation direction. In this way, the purpose is to change the mode diameter of the propagating light in the Δη change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. In an optical waveguide for waves,

The X-Y plot with the coordinates of the Δη change area along the light wave propagation direction as the X axis (X = 0 to L) and Δn as the Y axis is Δη (Χ) = Δη1-(Δ n 1 −Δη 2) An optical waveguide characterized by a curve represented by X (X / L) ^ω (0.1 <ω <0.75).

16. The optical waveguide according to any one of claims 12, 13, 14, and 15, wherein the optical waveguide is made of a polymer.

 17. The optical waveguide according to claim 16, wherein the core of the optical waveguide is composed of a polymer in which a dye that increases the refractive index of the core when mixed with the polymer is dispersed or combined. An optical waveguide, wherein the dye content of the core changes along the light wave propagation direction.

 1 8. The method for manufacturing an optical waveguide according to claim 17,

 A method of manufacturing an optical waveguide, comprising: controlling a light irradiation amount on the core to form a refractive index distribution in a light wave propagation direction of the core.

 19. The optical waveguide according to claim 18, wherein the waveguide is made of a fluorinated polymer, and the fluorine content of the light wave propagating portion of the waveguide changes along the light propagation direction. An optical waveguide characterized in that Δη changes.

 20. The optical waveguide according to claim 19,

The fluorinated polymer is represented by the above-mentioned chemical formula (Ο ^ χ ^ 1), and the _polymer is obtained by substituting _{1 CraF 2m + 1} (m = l to 5) for the polymer. An optical waveguide, comprising an introduced polyimide.

2 1. In the optical waveguide according to claim 20, Increasing the refractive index of the fluorinated polymer by electron beam irradiation and changing the amount of irradiated electrons along the light wave propagation direction causes the refractive index of the electron beam irradiated portion to change in the light wave propagation direction. The manufacturing method of the optical waveguide characterized by the above-mentioned.

22. Along the light wave propagation direction, the Δη change region where the refractive index difference n between the core and the cladding of the optical transmission path changes from Δη 1 to Δη 2 (Δη 1> Δη 2) Optical waveguide or optical fiber

 An optical waveguide or an optical fiber characterized in that a Χ-Υ plot in which the coordinate of the Δη change region along the light wave propagation direction is the X-axis and Δη is the Υ-axis is convex downward. .

 23. Along the optical wave propagation direction, the Δη change region where the refractive index difference μη between the core and the cladding of the optical transmission path changes from Δη1 to μη2 (Δη1> Δη2) Optical waveguide or optical fiber

The X—Υ plot with the coordinates of the Δη change area along the light wave propagation direction as the X axis (X = 0 to L) and Δη as the Υ axis is Δη (Χ) = Δη1-(Δ η 1 — um η 2) x (X / L) ° ^-1 and um n (X) = um n 1 — (um n 1 — A n 2) X (XZ L) ⁷⁵ An optical waveguide or an optical fiber characterized by being in a region surrounded by a curved line.

 2 4. Along the optical wave propagation direction, the Δη change region where the refractive index difference Δη between the core and the cladding of the optical path changes from Δη1 to Δη2 (Δη1> Δη2) Optical waveguide or optical fiber

 The X—Υ plot with the X-axis (Χ = 0) as the coordinates of the Δη change area along the light wave propagation direction and the Δ-axis as the Υ-axis is given by Δη (Χ) = Δη1-(Δ n 1-Δ η 2) x (XZ L) "(0.1 <ω, 0.75). An optical waveguide or an optical fiber characterized by the characteristic curve.

2 5. The optical waveguide whose mode field diameter at the input and output ends expands or contracts An optical fiber array according to any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24, wherein the optical fiber array includes an optical fiber array. An optical fiber array comprising a fiber.

 26. In an optical fiber array including an optical waveguide whose mode field diameter at the input and output ends expands or contracts,

 An optical waveguide whose mode field diameter does not change, and an optical waveguide according to any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24 Optical waveguide or optical fiber is placed adjacent to

An optical fiber array characterized by this.

 27. The mode field diameter at the input / output end described in any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20, and 22 to 24. An optical input / output device that includes an optical waveguide that expands or contracts.

 28. In the connection form of an optical waveguide and an optical waveguide or an optical fiber having a core diameter larger than the core diameter of the waveguide,

 The optical waveguide having a smaller core diameter is a Δη control waveguide according to any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20, and 22 to 24. A connection form characterized by a wave path.

29. Includes a rectangular polymer waveguide and a heating means for locally heating the waveguide, and switches the optical path of the waveguide by changing the temperature of the polymer locally. In a switch substrate and an optical path switching device including an optical fiber or an optical waveguide for introducing input light into the optical path switching switch substrate or deriving output light from the optical path switching switch substrate, It includes a Δη control waveguide according to any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24. Optical path switching device.

30.—Includes one or more outgoing optical waveguides or optical fibers and two or more receiving optical waveguides or optical fibers, with the outgoing end of the outgoing optical waveguide or optical fiber. This is done by selecting only one receiving optical waveguide or optical fiber to be connected and connecting the selected waveguide or optical fiber to the transmitting waveguide or optical fiber. Therefore, in an optical switch for switching the optical path of an optical signal from a specific receiving optical waveguide or optical fiber to another receiving optical waveguide or optical fiber,

 An optical waveguide or an optical fiber according to any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24. An optical path switching switch characterized by the following.

 3 1 .—Includes one or more outgoing optical waveguides or optical fibers and two or more receiving optical waveguides or fibers, with the outgoing end of the outgoing optical waveguide or optical fiber. By selecting only one receiving optical waveguide or optical fiber to be connected, and connecting the selected waveguide or optical fiber to the transmitting waveguide or optical fiber, a specific In an optical switch for switching the optical path of an optical signal from a receiving optical waveguide or fiber to another receiving optical waveguide or fiber,

 An optical waveguide or optical fiber comprising two or more optical waveguides or optical fibers according to any one of claims 12 to 17, 19, 20 and 22 to 24. An optical path switching switch for connecting an optical waveguide or an optical fiber by abutting end faces having Δη of Δiva of Δiva 2.

3 2 .—Includes one or more outgoing optical waveguides or optical fibers and two or more receive optical waveguides or optical fibers, with the outgoing end of the outgoing optical waveguide or optical fiber. Select only one receiving optical waveguide or optical fiber to connect, and connect the selected waveguide or optical fiber to the transmitting optical waveguide or optical fiber. By connecting, in an optical switch that switches the optical path of an optical signal from a specific receiving optical waveguide or optical fiber to another receiving optical waveguide or optical fiber,

 A plurality of cantilever beams formed on a silicon substrate and connected to each other by a connecting member, an optical waveguide formed on at least one cantilever, and the optical waveguide A plurality of optical waveguides fixed to face each other, and switch driving means for deforming the cantilever, and both the optical waveguide formed on the cantilever and the fixed optical waveguide An optical switch according to any one of claims 1 to 3, 5 to 7, 11 to 17, 19, 20 and 22 to 24.

 3 3. In an optical input / output device including a laser diode, an optical waveguide in which the laser oscillation wavelength light is guided in a single mode in a fiber, and an optical fiber,

 The optical waveguide is the optical waveguide according to any one of claims 12 to 17, 19, and 20, and the optical fiber is the optical waveguide according to any one of claims 22 to 24. The optical fiber described in the above section, wherein the optical waveguide is connected to the optical fiber by abutting the end faces of the optical fiber and the optical fiber where Δη is Δη2. An input / output device characterized in that:

 3 4. Wavelength selection filter: In an optical waveguide with an optical element or an optical fiber in which an optical element such as an optical element is inserted between the optical fiber or the optical fiber, the optical element Claims 1 to 3, 5 to 7, 11 to 17, 19, 19, 20, 22 include the nod region including the end face on the optical element side of the optical waveguide or the optical fiber sandwiching the optical waveguide. 25. An optical waveguide or an optical fiber with an optical element, characterized by being the optical waveguide or the optical fiber according to any one of items 24 to 24.

3 5. The laser diode and the laser oscillation wavelength light Claims 1 to 3, 5 to 7, 11 to 17, 19, 20, 20, 22 to 2 in an optical input / output device including an optical waveguide and an optical fiber that perform single-mode waveguide. An optical input / output device comprising the optical waveguide or the optical fiber according to 4.

 36. The laser diode and the laser oscillation wavelength light are guided in a single mode in the fiber, and the mode diameter of the mode is the same as the mode diameter of the laser light at the emission end of the laser diode. In an optical input / output device that includes different optical fibers,

 Between the laser diode and the optical fiber, the refractive index difference n between the waveguide core and the cladding changes along the lightwave propagation direction from Δη1 to μη2 (Δη1> Δη2). The purpose of the present invention is to change the mode diameter of the propagating light in the Δη change region by having a Δη change region, and the cross-sectional shape of the core does not change along the light wave propagation direction. There is an optical waveguide for waves, and the mode diameter of the waveguide at the laser diode side end face is laser diode so that the coupling efficiency between the laser diode and the optical waveguide is 90% or more. The mode diameter at the optical fiber side end face of the optical waveguide is adjusted so that the mode diameter matches the optical fiber and the coupling efficiency between the optical waveguide and the optical fiber is 90% or more. Light input / output characterized by matching the mode diameter of the bar Apparatus.