EP0153124A2
Expired / Lapsed
EP
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Acousto-optic frequency shifter
Assignee: Leland Stanford Junior University
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Filing: 1985-02-11
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Granted: —
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Expires: 2005-02-11
Abstract
Abstract A fiber optic frequency shifter comprises an optical fiber (54) having two propagation modes and an acoustic transducer (50) for generating an acoustic wave. The transducer (50) is positioned relative to the fiber (54) to cause the wave fronts of the acoustic wave to acoustically contact the fiber (54) at an angle of incidence (0) which is less than 90° greater than 0°. Preferably, the wavelength of the acoustic wave is substantially equal to the beat length of the fiber (54) times the sine of the angle of incidence (θ.
Inventors
- 👤 Herbert J. Shaw
- 👤 Robert C. Youngquist
- 👤 Gordon S. Kino
- 👤 William P. Risk
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 12:48
CPC Classifications
G; G02; G02B; G02B26/00; G02F; G02F1/00; G02F1/01; G02F1/0128; G02F1/0131; G02F1/0134; G02B6/00; G02B6/24; G02B6/26; G02B6/28; G02B6/2804; G02B6/2821
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
69 words
A fiber optic frequency shifter, comprising: an optical fiber (54) having first and second modes which propagate light at first and second velocities, respectively; and an acoustic transducer (50) for generating an acoustic wave, said transducer positioned relative to said fiber to cause the wave fronts of said acoustic wave to acoustically contact said fiber at an angle of incidence which is less than 90° but greater than 0°.
Claim 2
Dependent Claim
69 words
A fiber optic frequency shifter, comprising: an optical fiber (54) having first and second modes which propagate light at first and second velocities, respectively; and an acoustic transducer (50) for generating an acoustic wave, said transducer positioned relative to said fiber to cause the wave fronts of said acoustic wave to acoustically contact said fiber at an angle of incidence which is less than 90° but greater than 0°.
Claim 3
Dependent Claim
34 words
A fiber optic frequency shifter, as defined by claim 1, wherein said fiber is a birefringent single mode fiber and said modes are the two orthogonal polarization modes of said birefringent single mode fiber.
Claim 4
Dependent Claim
35 words
A fiber optic frequency shifter, as defined by claim 1, wherein the wavelength of said acoustic wave is substantially equal to the beat length of said fiber times the sine of the angle of incidence.
Claim 5
Dependent Claim
19 words
A fiber optic frequency shifter, as defined by claim 1, wherein said acoustic wave is a bulk acoustic wave.
Claim 6
Dependent Claim
45 words
A fiber optic frequency shifter, as defined by claim 1, additionally comprising: a member (94) having a surface (98), said fiber (92) positioned in acoustic contact with said surface (98) and said acoustic wave comprising a surface acoustic wave which propagates along said surface (98).
Claim 7
Dependent Claim
35 words
A fiber optic frequency shifter, as defined by claim 5, wherein said transducer (102) is movably mounted for positional adjustment relative to said fiber to selectively vary said angle of incidence of said acoustic wave.
Claim 8
Dependent Claim
19 words
A fiber optic frequency shifter, as defined by claim 1, wherein said angle of incidence is less than 30°.
Claim 9
Dependent Claim
33 words
A fiber optic frequency shifter, as defined by claim 1, additionally comprising a substrate (140) for preferentially guiding the acoustic energy of said acoustic wave substantially along the axis of said fiber (142).
Claim 10
Dependent Claim
20 words
A fiber optic frequency shifter, as defined by claim 1, wherein said substrate (140) is formed from an anisotropic material.
Claim 11
Dependent Claim
48 words
A fiber optic frequency shifter, as defined by claim 1, wherein said acoustic wave causes light input in said first mode to be coupled to said second mode such that said coupled light is shifted in frequency by an amount equal to the frequency of said acoustic wave.
Claim 12
Dependent Claim
28 words
A fiber optic frequency shifter, as defined by claim 10, additionally comprising: a modal filter (80) for suppressing output light from said frequency shifter in said first mode.
Claim 13
Independent Claim
98 words
A method of increasing the amount of frequency shift produced by a fiber optic frequency shifter comprising an optical fiber having two modes, said method comprising: generating an acoustic wave; and directing said acoustic wave such that its wave fronts make acoustic contact with said fiber at an angle of incidence which is less than 90° but greater than 0°, so that light .input to said optical fiber in one of said two modes is coupled to the other of said two modes and shifted in frequency by an amount equal to the frequency of said acoustic wave.
Claim 14
Independent Claim
98 words
A method of increasing the amount of frequency shift produced by a fiber optic frequency shifter comprising an optical fiber having two modes, said method comprising: generating an acoustic wave; and directing said acoustic wave such that its wave fronts make acoustic contact with said fiber at an angle of incidence which is less than 90° but greater than 0°, so that light .input to said optical fiber in one of said two modes is coupled to the other of said two modes and shifted in frequency by an amount equal to the frequency of said acoustic wave.
Claim 15
Dependent Claim
32 words
A method as defined by claim 12, wherein the wavelength of said acoustic wave is substantially equal to the beat length of said fiber times the sine of said angle of incidence.
Claim 16
Dependent Claim
16 words
A method as defined by claim 12, wherein said acoustic wave is a bulk acoustic wave.
Claim 17
Dependent Claim
53 words
A method as defined in Claim 12, wherein said acoustic wave is directed to acoustically contact said fiber to cause said frequency shifting, such that the phase propagation direction of said wave is at an angle to said fiber, while the energy propagation direction of said wave is substantially parallel to said fiber.
References Cited (Backward Citations)
No citation records indexed.
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