Stress-optical phase modulator and modulation system and method of use
First Claim
1. A method for phase modulation of an optical beam, which method comprises:
- a) providing an optical beam;
b) providing a transparent, stress-optical material having an inlet window and an outlet window, the material chosen so as to change uniformly its index of refraction in response to a homogeneous stress field;
c) introducing the optical beam into the inlet window of the optical material for receiving the beam through the optical material;
d) applying a predetermined force to the optical material to create uniform stress within and throughout the optical material sufficient to form a substantially uniform change in an index of refraction throughout the optical material to a selected index of refraction to effect a change in the velocity of the optical beam through the optical material; and
e) recovering a stress-induced, phase modulated optical beam from an outlet window of an optical material.
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Abstract
A stress-optical phase modulator and modulation system, and method of use of the same is described. The stress-optical phase modulator comprises a source for providing optical beams, a photoelastic optical material, and a means for applying mechanical force to the optical material. The mechanical force so applied creates a uniform stress within the optical material and results in a change in its index of refraction. An optical beam passing through the stressed optical material undergoes a phase change and is recovered as a phase modulated optical beam. Components may be added to the stress-optical phase modulator to produce temperature-compensated and intensity-modulated optical beams.
46 Citations
19 Claims
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1. A method for phase modulation of an optical beam, which method comprises:
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a) providing an optical beam; b) providing a transparent, stress-optical material having an inlet window and an outlet window, the material chosen so as to change uniformly its index of refraction in response to a homogeneous stress field; c) introducing the optical beam into the inlet window of the optical material for receiving the beam through the optical material; d) applying a predetermined force to the optical material to create uniform stress within and throughout the optical material sufficient to form a substantially uniform change in an index of refraction throughout the optical material to a selected index of refraction to effect a change in the velocity of the optical beam through the optical material; and e) recovering a stress-induced, phase modulated optical beam from an outlet window of an optical material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for providing a compensated, phase modulated optical beam, which method comprises:
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a) providing a stress optical material having an inlet window and an outlet window, the material adapted to change its index of refraction uniformly in response to uniform stress; b) passing a first optical beam in a first channel of the material from the inlet to the outlet windows; c) applying to said first section through a first force means secured to a first channel of the optical material a predetermined force sufficient to form a substantially uniform change in the index of refraction of said first channel to recover a first phase modulated optical beam from the outlet window; d) dividing a second optical beam into two equal, coherent beams 2A and 2B; e) passing optical beam 2A in a second channel of the optical material through a tunnel section composed of a material insensitive to the factor to be compensated to recover from the outlet window a phase reference optical beam; f) passing optical beam 2B in a third channel of the optical material to the outlet window, which optical beam 2B is phase modulated by the factor to be compensated; g) combining the factor phase modulated optical beam 2B and the phase reference optical beam 2A to provide a compensated, modulated outlet optical beam; h) detecting the compensated, modulated outlet optical beam to produce a factor-compensating signal; i) feeding the signal to a second force secured to the means to apply a sufficient force to the second channel to change substantially and to change uniformly the index of refraction of the second channel sufficient to compensate for the phase change caused by the factor to be compensated; j) feeding the signal to the first force means to apply sufficient force to uniformly change the index of refraction of the first channel sufficient to compensate for the phase change caused by the factor to be compensated; and k) recovering a factor-compensated, phase-modulated first optical beam from the outlet window. - View Dependent Claims (12, 13, 14)
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15. A temperature-compensating, phase-modulated optical beam system, which system comprises:
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a) a source of a first optical beam; b) a source of a second optical beam; c) a stress optical material having an inlet window to receive the first optical beam and second optical beam, and an outlet window to recover the first and second optical beams, the stress optic material adapted to change uniformly its indexed refraction in response to uniformly applied stress; d) a beam splitter means to divide the second optical beam into at least 2A and 2B optical beams for introduction into the inlet window; e) spaced apart, generally parallel first, second and third channels in the optical material, the second channel having a tunnel composed of a temperature-insensitive material, the first optical beam passing through the first channel, the beam 2A passing through the tunnel as a reference beam, and the beam 2B passing through the third channel; f) first and second force means each comprising strictive plates secured to the first and second channels of the optical material to place in response to electrical signals a predetermined force on the respective channels of the optical material to change substantially uniformly the index of refraction of the optical material throughout the optical material in response to electrical signals and to phase modulate the first and 2B optical beams; g) beam coupler means to recombine the optical beams 2A and 2B to provide a modulated optical beam; h) a photo detector means to receive the modulated optical beam and to produce an electrical signal responsive thereto; i) a feedback means electrically connected to the first force means and the second force means to apply a predetermined force to the first and second channels to temperature compensate the optical beam 2B and the first optical beam to provide a first optical phase-modulated, temperature-compensated optical beam. - View Dependent Claims (16, 17, 18, 19)
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Specification