US5199038A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor laser noise reduction
Assignee: Individual
•
Filing: 1991-05-14
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Granted: 1993-03-30
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Expires: 2011-05-14
Abstract
Abstract Amplitude or intensity noise in the output of a laser in detuned operation is reduced by application of a frequency dependent transfer function which exploits amplitude-phase coupled noise described by the linewidth enhancement parameter α by applying an inverse of a replica of the amplitude noise recovered from the phase noise to the laser output. The noise canceling amplitude is applied to the laser output by a filter whose frequency dependent transfer function is related to the inverse of the amplitude-phase noise transfer function of the laser producing the output. The appropriate transfer function may be selected and/or adjusted in response to the magnitude of the amplitude noise. The intensity noise may be reduced by the factor 1/(1+α 2 ) which may squeeze the intensity noise below normal quantum limits.
Inventors
- 👤 Kerry J. Vahala
- 👤 Michael A. Newkirk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:40
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/005; H01S5/0085; H01S2301/00; H01S2301/02; H01S5/0064
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
120 words
A laser system for producing reduced amplitude noise output, comprising: a detuned laser for providing detuned laser output, said detuned laser output having amplitude noise and phase noise, said amplitude noise being related to said phase noise by an inherent amplitude-phase coupled noise transfer function; filter means for producing a filter output in response to a filter input, amplitudes of said filter input and said filter output being related to each other by a frequency dependent amplitude transfer function substantially inversely related to said inherent amplitude-phase coupled noise transfer function; and means for coupling said detuned laser output to said filter input, whereby phase noise in said detuned laser output is used to reduce amplitude noise in said filter output.
Claim 2
Dependent Claim
120 words
A laser system for producing reduced amplitude noise output, comprising: a detuned laser for providing detuned laser output, said detuned laser output having amplitude noise and phase noise, said amplitude noise being related to said phase noise by an inherent amplitude-phase coupled noise transfer function; filter means for producing a filter output in response to a filter input, amplitudes of said filter input and said filter output being related to each other by a frequency dependent amplitude transfer function substantially inversely related to said inherent amplitude-phase coupled noise transfer function; and means for coupling said detuned laser output to said filter input, whereby phase noise in said detuned laser output is used to reduce amplitude noise in said filter output.
Claim 3
Dependent Claim
17 words
The laser system claimed in claim 1, wherein said detuned laser further comprises: a detuned semiconductor laser.
Claim 4
Dependent Claim
55 words
The laser system claimed in claim 1, wherein said filter means further comprises: means for canceling a portion of said amplitude noise in said detuned laser output by converting a portion of said phase noise into an inverted replica of the portion of said amplitude noise related thereto by said amplitude-phase coupled noise transfer function.
Claim 5
Dependent Claim
18 words
The laser system claimed in claim 3, further comprising: means for adjusting said frequency dependent amplitude transfer function.
Claim 6
Dependent Claim
40 words
The laser system claimed in claim 3, wherein said filter means further comprises: an interferometer having said frequency dependent amplitude transfer function; and means for adjusting the interferometer transfer function to control the portion of said amplitude noise being canceled.
Claim 7
Dependent Claim
51 words
The laser system claimed in claim 5, wherein said means for adjusting the interferometer transfer function further comprises: means for determining the amplitude noise in the output of said interferometer; and means responsive to said means for determining amplitude noise for adjusting the interferometer transfer function to reduce said amplitude noise.
Claim 8
Dependent Claim
16 words
The laser system claimed in claim 5, wherein said interferometer further comprises: an unbalanced Michelson interferometer.
Claim 9
Dependent Claim
60 words
The laser system claimed in claim 6, wherein said means for adjusting the interferometer transfer function further comprises: means for detecting amplitude noise in the output of the Michelson interferometer; means responsive to the amplitude noise in said detected output; and means response to said detected amplitude noise for changing the optical path length difference in said unbalanced Michelson interferometer.
Claim 10
Independent Claim
84 words
A method of producing laser output, comprising: providing detuned laser output having amplitude noise and phase noise, a portion of said phase noise being related to a portion of said amplitude noise by an amplitude-phase coupled noise transfer function; producing a reduced amplitude noise output in response to said detuned laser output with an optical device having a frequency dependent amplitude transfer function inversely related to said noise transfer function, said reduced amplitude noise output having less amplitude noise than said detuned laser output.
Claim 11
Independent Claim
84 words
A method of producing laser output, comprising: providing detuned laser output having amplitude noise and phase noise, a portion of said phase noise being related to a portion of said amplitude noise by an amplitude-phase coupled noise transfer function; producing a reduced amplitude noise output in response to said detuned laser output with an optical device having a frequency dependent amplitude transfer function inversely related to said noise transfer function, said reduced amplitude noise output having less amplitude noise than said detuned laser output.
Claim 12
Dependent Claim
33 words
The method of producing laser output claimed in claim 9, further comprising the step of: adjusting said frequency dependent amplitude transfer function to minimize said amplitude noise in said reduced amplitude noise output.
Claim 13
Dependent Claim
60 words
The method of producing laser output claimed in claim 9, wherein said optical device is an interferometer having a frequency dependent interferometer amplitude transfer function inversely related to said reduced amplitude noise transfer function, the method further comprising the step of: adjusting said frequency dependent interferometer amplitude transfer function to minimize said amplitude noise in said reduced amplitude noise output.
Claim 14
Dependent Claim
59 words
The method claimed in claim 11, wherein said step of adjusting said frequency dependent interferometer amplitude transfer function further comprises the steps of: detecting amplitude noise in said reduced amplitude noise output; and adjusting said frequency dependent interferometer amplitude transfer function in response to said detected amplitude noise to minimize said amplitude noise in said reduced amplitude noise output.
Claim 15
Dependent Claim
50 words
The method claimed in claim 12, wherein said interferometer is an unbalanced Michelson interferometer having first and second optical path lengths, and said step of adjusting said frequency dependent interferometer amplitude transfer function further comprises: adjusting said second optical path length with respect to said first an optical path length.
Claim 16
Dependent Claim
95 words
A laser system, comprising: detuned laser means for producing laser output having unwanted amplitude noise and phase noise, a portion of said phase noise in said laser output varying as a function of amplitude noise in said laser output; and means for receiving said laser output as an input and for producing a modified output whose amplitude is related to said input by a frequency dependent amplitude transfer function substantially inversely related to said function of amplitude noise, whereby phase noise in said laser output is used to reduce amplitude noise in said modified output.
Claim 17
Dependent Claim
95 words
A laser system, comprising: detuned laser means for producing laser output having unwanted amplitude noise and phase noise, a portion of said phase noise in said laser output varying as a function of amplitude noise in said laser output; and means for receiving said laser output as an input and for producing a modified output whose amplitude is related to said input by a frequency dependent amplitude transfer function substantially inversely related to said function of amplitude noise, whereby phase noise in said laser output is used to reduce amplitude noise in said modified output.
Claim 18
Dependent Claim
18 words
The laser system claimed in claim 14, wherein said detuned laser means further comprises: a detuned semiconductor laser.
Claim 19
Dependent Claim
35 words
The laser system claimed in claim 14, wherein said means for receiving and producing further comprises: means for varying said amplitude of said modified output as a function of the frequency of the phase noise.
Claim 20
Dependent Claim
38 words
The laser system claimed in claim 16, wherein said means for varying said amplitude further comprises: unbalanced interferometer means; and means for adjusting the variation of said amplitude as a function of frequency to minimize said amplitude noise.
Claim 21
Dependent Claim
25 words
The laser system claimed in claim 17, wherein said unbalanced interferometer means further comprises: an unbalanced Michelson interferometer having a difference in optical path lengths.
Claim 22
Dependent Claim
35 words
The laser system claimed in claim 18, wherein said means for adjusting further comprises: means response to amplitude noise in said modified output for changing the optical path length difference in said unbalanced Michelson interferometer.
References Cited (Backward Citations)
US4464759A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-03-29 | 1996-09-28 | 1997-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-03-29 | 2000-09-28 | 2001-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-03-29 | 2004-09-28 | 2005-03-30 | $7700.00 | Window Closed / Lapsed |