Solid-state optical interferometer

• US 4,708,480 A
• Filed: 10/16/1984
• Issued: 11/24/1987
• Est. Priority Date: 10/17/1983
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shibata, Takanori, Oho, Shigeru, Endo, Akira, Kanke, Atsushi, Sasayama, Takao
• Primary Examiner(s): Willis, Davis L.
• Assistant Examiner(s): Turner, S. A.
• Application Number:
  US06/661,454
• Time in Patent Office: 1,134 Days
• Field of Search: 356/345, 356/350, 350/96.13, 350/96.17
• US Class Current: 356/464
• CPC Class Codes: G01C 19/72 with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
• CPC Class Codes: G02F 1/125 in an optical waveguide structure
• CPC Class Codes: G02F 1/225 in an optical waveguide structure

Abstract

In a solid-state optical interferometer having a light path composed of a loop-shaped optical fiber and a solid-state light wave guide optically coupled to said optical fiber, electrodes for producing a surface acoustic wave (SAW) are formed as a pair on a surface of a substrate on which said solid-state light wave guide is formed, and said surface acoustic wave is used to apply optical modulation to a light beam passing through said solid-state light wave guide.

Claims

1. A solid-state optical interferometer comprising:

a loop-shaped optical fiber having end portions;

a solid-state light wave guide optically coupled to said optical fiber, said solid-state light wave guide forming a light path in conjunction with said optical fiber for enabling mixing of light received from the end portions of said optical fiber;

electrodes for producing a surface acoustic wave (SAW), said surface acoustic wave being used to apply optical modulation to a light beam passing through said solid-state light wave guide, said electrodes being formed as a pair on a surface of a substrate on which said solid-state light wave guide is formed;

said solid-state light wave guide formed on said substrate including two pieces of input light wave guides arranged on said substrate so as to form a predetermined angle therebetween, and at least one piece of output light wave guide coupled to said two pieces of input light wave guides, light beams fed from said two pieces of input light wave guides being recombined into an interference beam by said surface acoustic wave (SAW), said interference beam being sent out through said at least one piece of output light wave guide;

a detector circuit for detecting a direction change of a car by utilizing said interference beam; and

a circuit for correcting a change generated in the output of said detector circuit while the car is not running.

2. A solid-state optical interferometer according to claim 1, wherein said electrodes formed on said substrate are connected to an optical modulation oscillator unit, and the oscillation output of said oscillator unit is so controlled by said interference beam as to cancel a change in phase produced by said recombination of said interference beam.

3. A solid-state optical interferometer according to claim 1, further comprising a laser beam generating circuit for feeding a laser beam to said light path, said laser beam generating circuit comprising a circuit for always changing the wavelength of said laser beam so as to prevent a standing wave from appearing in said light path.

4. A solid-state optical interferometer according to claim 1, wherein the end portions of said loop-shaped optical fiber include first and second end portions respectively coupled to first and second light wave guide portions at confronting end surfaces thereof, said solid-state light wave guide including a holding member having V-shaped grooves formed therein for receiving the end portions of said loop-shaped optical fiber therein, the end portions of said loop-shaped optical fiber being fixedly secured within said grooves.

5. A solid-state optical interferometer according to claim 4, wherein said V-shaped grooves are anisotropic silicon etched grooves, and said solid-state light wave guide includes portions coupled together by electrostatic bonding.

6. A solid-state interferometer comprising:

a loop-shaped optical fiber having end portions;

a solid-state light wave guide optically coupled to said optical fiber, said solid-state light wave guide forming a light path in conjunction with said optical fiber for enabling mixing of light received from the end portions of said optical fiber;

electrodes for producing a surface acoustic wave (SAW), said surface acoustic wave being used to apply optical modulation to a light beam passing through said solid-state light wave guide, said electrodes being formed as a pair on a surface of a substrate on which said solid-state light wave guide is formed;

said solid-state light wave guide formed on said substrate including two pieces of input light wave guides arranged on said substrate so as to form a predetermined angle therebetween; and

at least one piece of output light wave guide coupled to said two pieces of input light wave guides, light beams fed from said two pieces of input light wave guides being recombined into an interference beam by said surface acoustic wave (SAW), said interference beam being sent out through said at least one piece of output light wave guide;

a detector circuit for detecting a direction change of a car by utilizing said interference beam; and

a circuit for averaging a change generated in the output of said detector circuit while the car is not running.

7. A soild-state optical interferometer according to claim 6, wherein said electrodes formed on said substrate are connected to an optical modulation oscillator unit, and the oscillation output of said oscillator unit is so controlled by said interference beam as to cancel a change in phase produced by said recombination of said interference beam.

8. A solid-state optical interferometer according to claim 6, further comprising a laser beam generating circuit for feeding a laser beam to said light path, said laser beam generating circuit comprising a circuit for always changing the wavelength of said laser beam so as to prevent a standing wave from appearing in said light path.

9. A solid-state optical interferometer according to claim 6, wherein the end portions of said loop-shaped optical fiber include first and second end portions respectively coupled to first and second light wave guide portions at confronting end surfaces thereof, said solid-state light wave guide including a holding member having V-shaped grooves formed therein for receiving the end portions of said loop-shaped optical fiber therein, the end portions of said loop-shaped optical fiber being fixedly secured within said grooves.

10. A solid-state optical interferometer according to claim 9, wherein said V-shaped grooves are anisotropic silicon etches grooves, and said solid-state light wave guide includes portions coupled together by electrostatic bonding.