EP0253590A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Synchronously pumped ring fiber raman laser
Assignee: Leland Stanford Junior University
•
Filing: 1987-07-10
•
Granted: —
•
Expires: 2007-07-10
Abstract
Abstract An all-fiber ring laser has a single, uninterrupted length of single-mode optical fiber (100) that is formed into a loop (104) by using an optical coupler (110). Pump signal pulses (114) at a first optical wavelength are introduced into one end (102) of the optical fiber (100). Each pump pulse (114) propagates through the loop (104) formed in the fiber (100) and then exits the fiber (100). The pump signal pulses (114) excite the molecules of the optical fiber (100) to cause them to go to a higher, unstable energy level. When the molecules return to a lower energy level, photons are emitted at a second optical frequency that has a wavelength that is shifted from the wavelength of the pump signal to form laser signal pulses. The coupler (110) is a multiplexing coupler (110) that has a first coupling ratio (η p ) at the wavelength of the pump signal and has a second coupling ratio (η s ) at the wavelength of the emitted optical signal. The first coupling ratio (η p ) is preferably close to zero and the second coupling ratio (η s ) is greater than 0.5. The laser optical signal recirculates in the loop (104) to stimulate further emission of optical energy at the shifted wavelength in phase with the recirculating optical signal. Each pump pulse is timed to enter the optical fiber loop (104) in synchronism with the recirculating laser signal pulse so as to excite the fiber molecules so as to amplify the recirculating signal pulses. The laser signal has a loop transit time related to the time interval (T) between pump pulses such that a multiple of the loop transit time is substantially equal to a multiple of the time interval (T).
Inventors
- 👤 Emmanual Desurvire
- 👤 Herbert J. Shaw
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 17:26
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/09; H01S3/091; H01S3/094; H01S3/094026; H01S3/30; H01S3/302
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
243 words
An apparatus for generating a laser signal characterized by: a source (112) of pump optical energy at a first wavelength for producing plural energy bursts (114) that are spaced apart in time by a selected time interval (T); a length of optical fiber (100) that receives said series of energy bursts, said length of optical fiber (100) forming a loop (104); and a coupler (110) that optically closes said loop (104) and that couples said energy bursts (114) to said loop (104) to propagate in said loop (104) to pump said fiber (100) and cause emission of optical energy in said fiber (100) at a second wavelength that is shifted from said first wavelength, and thereby provide a laser signal at said second wavelength, said coupler (110) having a first coupling ratio (η p ) at said first wavelength such that substantially all of the energy in said energy bursts (114) is coupled into said loop (104), said coupler (110) further causing substantially all of the energy bursts traversing said loop (104) to exit said loop (104), said coupler (110) having a second coupling ratio (η s ) at said second wavelength, said second coupling ratio (η s ) such that said laser signal recirculates in said loop (104), said laser signal having a loop transit time related to said time interval (T) such that a multiple of the loop transit time is substantially equal to a multiple of said time interval (T).
Claim 2
Independent Claim
243 words
An apparatus for generating a laser signal characterized by: a source (112) of pump optical energy at a first wavelength for producing plural energy bursts (114) that are spaced apart in time by a selected time interval (T); a length of optical fiber (100) that receives said series of energy bursts, said length of optical fiber (100) forming a loop (104); and a coupler (110) that optically closes said loop (104) and that couples said energy bursts (114) to said loop (104) to propagate in said loop (104) to pump said fiber (100) and cause emission of optical energy in said fiber (100) at a second wavelength that is shifted from said first wavelength, and thereby provide a laser signal at said second wavelength, said coupler (110) having a first coupling ratio (η p ) at said first wavelength such that substantially all of the energy in said energy bursts (114) is coupled into said loop (104), said coupler (110) further causing substantially all of the energy bursts traversing said loop (104) to exit said loop (104), said coupler (110) having a second coupling ratio (η s ) at said second wavelength, said second coupling ratio (η s ) such that said laser signal recirculates in said loop (104), said laser signal having a loop transit time related to said time interval (T) such that a multiple of the loop transit time is substantially equal to a multiple of said time interval (T).
Claim 3
Dependent Claim
50 words
The apparatus as defined in Claim 1, wherein said source (112) of pump optical energy is characterized by a laser signal source (140) that generates optical energy at said first wavelength and wherein said pump energy bursts (114) are formed by modulating said optical energy to create a modulated waveform.
Claim 4
Dependent Claim
14 words
The apparatus as defined in Claim 2, wherein said modulated waveform is a pulse.
Claim 5
Dependent Claim
25 words
The apparatus as defined in Claim 3, wherein said pulse switches between an energy level substantially equal to zero and a predetermined maximum energy level.
Claim 6
Dependent Claim
23 words
The apparatus as defined in Claim 1, wherein said emission of optical energy at said second wavelength is the result of Raman scattering.
Claim 7
Dependent Claim
28 words
The laser as defined in Claim 1, wherein said second coupling ratio (η s ) is greater than 0.5 and said first coupling ratio is close to zero.
Claim 8
Independent Claim
248 words
An apparatus for generating a laser output signal (118), characterized by: a loop (104) of optical fiber (100) for propagating light, said loop (104) having a loop propagation time that is a function of the wavelength of light propagating therein; a generator (112) that generates a pump signal (114) comprising a series of at least first and second adjacent optical energy bursts spaced apart in time by a time interval (T), and at least third and fourth adjacent optical energy bursts spaced apart in time by said time interval (T), said pump signal (114) being at a first optical wavelength; and a coupler (110) that couples said pump signal (114) into said optical fiber loop (104) so that said pump signal (114) propagates in said loop (104), said pump signal (114) causing emission of optical energy in said fiber (100) at a second optical wavelength, shifted from said first optical wavelength, to provide a laser signal at said second wavelength, said coupler (110) closing the loop such that said laser signal at said second wavelength recirculates in said loop (104) and such that a fraction of said laser signal is output from said loop on each circulation to provide said laser output signal (118), said third and fourth energy bursts being spaced apart in time such that they arrive at said loop (104) subsequent to said first and second energy bursts, respectively, by a time equal to a multiple of the loop propagation time for said second wavelength.
Claim 9
Independent Claim
248 words
An apparatus for generating a laser output signal (118), characterized by: a loop (104) of optical fiber (100) for propagating light, said loop (104) having a loop propagation time that is a function of the wavelength of light propagating therein; a generator (112) that generates a pump signal (114) comprising a series of at least first and second adjacent optical energy bursts spaced apart in time by a time interval (T), and at least third and fourth adjacent optical energy bursts spaced apart in time by said time interval (T), said pump signal (114) being at a first optical wavelength; and a coupler (110) that couples said pump signal (114) into said optical fiber loop (104) so that said pump signal (114) propagates in said loop (104), said pump signal (114) causing emission of optical energy in said fiber (100) at a second optical wavelength, shifted from said first optical wavelength, to provide a laser signal at said second wavelength, said coupler (110) closing the loop such that said laser signal at said second wavelength recirculates in said loop (104) and such that a fraction of said laser signal is output from said loop on each circulation to provide said laser output signal (118), said third and fourth energy bursts being spaced apart in time such that they arrive at said loop (104) subsequent to said first and second energy bursts, respectively, by a time equal to a multiple of the loop propagation time for said second wavelength.
Claim 10
Independent Claim
329 words
A method of generating a laser signal in a fiber optic system having an input end portion (102), a loop portion (104) and an output end portion (106) of said optical fiber (100), said method characterized by the steps of: generating an optical pump singal (114) at a pump frequency, said pump signal (114) comprising bursts of optical energy spaced apart in time by a selectable time interval (T); providing said optical pump signal (114) as an input pump signal to said input end portion of said optical fiber (100); coupling substantially all of said input pump signal to said loop portion (104) of said optical fiber (100) to propagate in said loop portion (104) so that said loop portion (104) of said optical fiber (100) emits optical energy in response to said pump optical energy at a laser frequency that is shifted in frequency from said pump frequency by a frequency that is characteristic of said optical fiber (100); coupling substantially all of said pump signal in said loop portion (104) of said optical fiber (100) to said output end portion (106) of said optical fiber (100) so that said pump signal does not recirculate in said loop portion (104) of said optical fiber (100); propagating said emitted optical energy to said coupler (110) and coupling a first portion of said emitted optical energy to said output end portion (106) of said optical fiber (100) as an output signal (118) at said laser frequency, and coupling a second portion of said emitted optical energy back to said loop portion (104) of said optical fiber (100) to recirculate therein, said recirculating emitted optical signal traversing said loop portion (104) in a transit time determined by the length of said loop portion (104) of optical fiber (100) and the wavelength of said emitted optical signal; and selecting said time interval (T) between said bursts of optical energy to be substantially equal to the transit time of said emitted optical energy.
Claim 11
Independent Claim
329 words
A method of generating a laser signal in a fiber optic system having an input end portion (102), a loop portion (104) and an output end portion (106) of said optical fiber (100), said method characterized by the steps of: generating an optical pump singal (114) at a pump frequency, said pump signal (114) comprising bursts of optical energy spaced apart in time by a selectable time interval (T); providing said optical pump signal (114) as an input pump signal to said input end portion of said optical fiber (100); coupling substantially all of said input pump signal to said loop portion (104) of said optical fiber (100) to propagate in said loop portion (104) so that said loop portion (104) of said optical fiber (100) emits optical energy in response to said pump optical energy at a laser frequency that is shifted in frequency from said pump frequency by a frequency that is characteristic of said optical fiber (100); coupling substantially all of said pump signal in said loop portion (104) of said optical fiber (100) to said output end portion (106) of said optical fiber (100) so that said pump signal does not recirculate in said loop portion (104) of said optical fiber (100); propagating said emitted optical energy to said coupler (110) and coupling a first portion of said emitted optical energy to said output end portion (106) of said optical fiber (100) as an output signal (118) at said laser frequency, and coupling a second portion of said emitted optical energy back to said loop portion (104) of said optical fiber (100) to recirculate therein, said recirculating emitted optical signal traversing said loop portion (104) in a transit time determined by the length of said loop portion (104) of optical fiber (100) and the wavelength of said emitted optical signal; and selecting said time interval (T) between said bursts of optical energy to be substantially equal to the transit time of said emitted optical energy.
Claim 12
Dependent Claim
129 words
The method of generating a laser signal as defined in Claim 8, wherein said input end portion (102), said loop portion (104), and said output end portion (106) of said optical fiber (100) are characterized by a single, uninterrupted length of optical fiber (100) having an inner core and an outer cladding, and wherein said coupler (110) is characterized by a first facing surface formed on said fiber (100) between said input end portion (102) and said loop portion (104) and a second facing surface formed on said fiber between said loop portion (104) and said output end portion (106), said first and second facing surfaces juxtaposed so that optical energy is transferred between said input end portion (102) and said output end portion (106) at said facing surfaces.
Claim 13
Independent Claim
236 words
A method of generating a laser output signal (118), characterized by the steps of: generating a pump signal (114) comprising a series of at least first and second adjacent optical energy bursts spaced apart in time by a time interval (T), and at least third and fourth adjacent energy bursts spaced apart in time by said time interval (T), said pump signal (114) being at a first optical wavelength; inputting said first and second energy bursts into a loop (104) of optical fiber (100), said loop (104) having a loop propagation time for light propagating therethrough, said propagation time being a function of the wavelength of said light; propagating said first and second energy bursts in said optical fiber loop (104) to optically pump said fiber, and cause emission of optical energy in said optical fiber at a second optical wavelength, shifted from said first optical wavelength, to provide a laser signal at said second wavelength; inputting said third and fourth adjacent energy bursts into said loop (104); timing said third and fourth energy bursts to arrive at said loop (104) subsequent to said first and second energy bursts, respectively, by a time equal to a multiple of the loop propagation time for said second wavelength; recirculating said laser signal at said second wavelength in said loop (104); and outputting a fraction of said laser signal from said loop to provide said laser output signal (118).
Claim 14
Independent Claim
236 words
A method of generating a laser output signal (118), characterized by the steps of: generating a pump signal (114) comprising a series of at least first and second adjacent optical energy bursts spaced apart in time by a time interval (T), and at least third and fourth adjacent energy bursts spaced apart in time by said time interval (T), said pump signal (114) being at a first optical wavelength; inputting said first and second energy bursts into a loop (104) of optical fiber (100), said loop (104) having a loop propagation time for light propagating therethrough, said propagation time being a function of the wavelength of said light; propagating said first and second energy bursts in said optical fiber loop (104) to optically pump said fiber, and cause emission of optical energy in said optical fiber at a second optical wavelength, shifted from said first optical wavelength, to provide a laser signal at said second wavelength; inputting said third and fourth adjacent energy bursts into said loop (104); timing said third and fourth energy bursts to arrive at said loop (104) subsequent to said first and second energy bursts, respectively, by a time equal to a multiple of the loop propagation time for said second wavelength; recirculating said laser signal at said second wavelength in said loop (104); and outputting a fraction of said laser signal from said loop to provide said laser output signal (118).
Claim 15
Dependent Claim
22 words
The method of Claim 10, wherein said stimulated emission of optical energy at said second wavelength is the result of Raman scattering.
Claim 16
Dependent Claim
46 words
The method of Claim 10, wherein said propagating step includes the step of outputting substantially all of said pump signal from said loop (104) after said pump signal has traversed said loop (104) one time to avoid recirculation of said pump signal in said loop (104).
Claim 17
Dependent Claim
40 words
The method of Claim 10, wherein said recirculating laser signal has a sufficiently high intensity to pump said optical fiber (100) to cause emission of optical energy in said optical fiber at a third wavelength shifted from said second wavelength.
Claim 18
Dependent Claim
22 words
The method of Claim 10, wherein said stimulated emission of optical energy at said third wavelength is the result of Raman scattering.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.