Optical waveplate, method of manufacturing the same, and waveguide device using the same

Claim 2

Optical waveplate according to claim 1, wherein said fluorinated polyimide film has a repeating structure of a basic unit represented by the following general formula:

Claim 8

A method according to claim 6, wherein said polyimide film is peeled from said substrate, and a retardation is finely adjusted by further uniaxially drawing said polyimide film at a high temperature of not less than 300°C.

Claim 10

A waveguide device constituted by at least one optical waveguide formed on a substrate and at least one optical waveplate, wherein said at least one waveplate is inserted in at least one groove which is formed at a predetermined angle so as to be substantially perpendicular to at least one of said waveguides and to cross at least one of said waveguides, characterized in that said at least one optical waveplate is formed of a fluorinated, uniaxially drawn polyimide film with a thickness of not more than 20 µm.

Claim 11

A waveguide device according to claim 10, wherein the waveguide device is a polarization convertor comprising a single optical waveguide (1, 2) and a waveplate as defined in claim 10 which is a half waveplate (3) having a product of an in-plane anisotropy of refractive index and a thickness set to one-half of the wavelength of the guided light.

Claim 12

A waveguide device according to claim 10, wherein the waveguide device is a Mach-Zender interferometer comprising two input waveguides (6, 7), a first directional coupler (10) connected to said input waveguides (6, 7), two output waveguides (8, 9), a second directional coupler (13) connected to said output waveguides (8, 9), and first and second waveguides (11, 12) connecting said first and second directional couplers (10, 13), and wherein a polarization convertor having a waveplate as defined in claim 10 which is a half waveplate, is arranged in the middle of an optical path of each of said first and second waveguides (11, 12).

Claim 13

A waveguide device according to claim 10, wherein the waveguide device is a ring resonator comprising a plurality of input/output waveguides (1, 2), and a ring waveguide (15) coupled to said input/output waveguides (1, 2), and wherein at least one polarization convertor having a waveplate as defined in claim 10 which is a half waveplate, is arranged on said ring waveguide (15) in order that an equal optical path length of said ring waveguide (15) is obtained for input horizontal polarization light and vertical polarization light.

Claim 14

A waveguide device according to claim 10, wherein the waveguide device is a waveguide multi/demultiplexer using an arrayed-waveguide grating in which at least one input waveguide (1), a first slab waveguide (17) (input side), an arrayed waveguide (20) constituted by a plurality of channel waveguides (19), a second slab waveguide (18) (output side), and a plurality of output waveguides (2) are arranged in the order named on a waveguide substrate (5), and wherein a polarization convertor having a waveplate as defined in claim 10 which is a half waveplate, is arranged in the middle of each of said channel waveguides (19), which constitute said arrayed waveguide (20).

Claim 15

A waveguide device according to claim 10, wherein the waveguide device is a directional coupler (21) and wherein a polarization convertor having a waveplate as defined in claim 10 which is a half waveplate, is arranged in the middle of said directional coupler (21).

Claim 16

A waveguide device according to claim 10, wherein the waveguide device is a phase modulator comprising a waveguide (25) having an electrooptic effect, and a pair of electrodes (22, 23) arranged near said waveguide (25), and wherein at least one polarization convertor having a waveplate as defined in claim 10 which is a half waveplate, is arranged in the middle of said waveguide (25).

Claim 17

A waveguide device according to anyone of claims 11 to 16. wherein the waveplate constituting said polarization convertor is inserted into said substrate forming the waveguide device at an angle between 80° and 90°.

Claim 18

A waveguide device according to claim 10, wherein the waveguide device is a polarization beam splitter comprising two input waveguides (6, 7), a first directional coupler (10) connected to said input waveguides (6, 7), two output waveguides (8, 9), a second directional coupler (13) connected to said output waveguides (8, 9), and first and second waveguides (11, 12) connecting said first and second directional couplers (10, 13), said first and second waveguides (11, 12) having an optical path length difference which is a quarter of the wavelength of the guided light, and wherein waveplates (36) as defined in claim 10 are arranged in optical paths of said first and second waveguides (11, 12) so that their optical axes are, respectively, perpendicular and parallel to said waveguide substrate, and the product of the in-plane anisotropy of the refractive index and the thickness of each waveplate is set to a quarter of the wavelength of the guided light.

Claim 19

A waveguide device according to claim 10, wherein the waveguide device is a polarization beam splitter comprising two input waveguides (6, 7), a first directional coupler (10) connected to said input waveguides (6, 7), two output waveguides (8, 9), a second directional coupler (13) connected to said output waveguides (8, 9), and first and second waveguides (11, 12) connecting said first and second directional couplers (10, 13), said first and second waveguides (11, 12) having an optical path length difference which is a quarter of the wavelength of the guided light, and wherein a waveplate (3) as defined in claim 10 is arranged in an optical path of said first waveguide (11), wherein the optical principal axis of said waveplate is set so as to be horizontal or perpendicular to said waveguide substrate and wherein the product of the in-plane anisotropy of the refractive index and the thickness of said waveplate is set to a half of the wavelength of the guided light.

Claim 20

A waveguide device accordig to claim 19, wherein said waveplate (3) is inserted into said waveguide substrate (5) such that the optical principal axis of said half waveplate is perpendicular to said waveguide substrate (5), and a thermo-optic phase shifter is arranged in the optical path of said second waveguide (12).

Claim 21

A waveguide device accordig to claim 19, wherein said waveplate (3) is inserted into said waveguide substrate (5) such that the optical principal axis of said half waveplate is parallel to said waveguide substrate (5), and a thermo-optic phase shifter is arranged in the optical path of said second waveguide (12).

Claim 22

A waveguide device according to claim 10, comprising a first 2x2 polarization beam splitter (27) constituted by nonmagnetic waveguides, two nonreciprocal elements (31) constituted by magnetic waveguides, and a second 2x2 polarization beam splitter (32), wherein a waveplate (3) as defined in claim 10 is arranged between said two nonreciprocal elements (31) and said second 2x2 polarization beam splitter (32).

Claim 23

A waveguide device according to claim 22, wherein said waveplate (3) is a half waveplate, said half waveplate being inserted into said waveguide substrate such that the optical principal axis of said half waveplate forms an angle of 22.5° with said waveguide substrate (5).

Claim 24

A waveguide device according to claim 22, wherein said waveplate (3) is a half waveplate, said half waveplate being inserted into said waveguide substrate such that the optical principal axis of said half waveplate forms an angle of 67.5° with said waveguide substrate (5).

Claim 25

A waveguide device comprising an optical waveguide (1, 2) formed on a substrate (5), characterized in that it further contains an optical waveplate formed of a fluoridized, uniaxially drawn polyimide film with a thickness of not more than 20 µm, which is formed in tight contact with an end face of said optical waveguide (1, 2).

Claim 26

A waveguide device according to claim 25, wherein the waveplate being in tight contact with an end face of said waveguide is perpendicular to or inclined from a longitudinal direction of said waveguide and wherein a reflecting coat (35) is formed on the surface of said waveplate away from the end of said waveguide.

Claim 27

A waveguide device according to claim 25 or 26, wherein the waveguide device is a polarization convertor.

Claim 28

A device according to claim 27, wherein said optical waveplate (36) is a quarter waveplate having a product of the in-plane anisotropy of refractive index and the thickness set to a quarter of the wavelength of light propagating through said optical waveguide (1, 2), and the optical principal axis of said quarter waveplate forms an angle of 45° with said waveguide substrate.