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公开(公告)号：JP2000241239A
公开(公告)日：2000-09-08
申请号：JP21681298
申请日：1998-07-31
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , BELL STEVEN G
Abstract: PROBLEM TO BE SOLVED: To provide a fiber sensor system capable of high resolution measurement of frequency change. SOLUTION: An end injection fiber laser outputting a plurality of laser modes is installed. An optical fiber 14 transferring a laser mode is connected with an active fiber sensor 16. The optical fiber 14 transfers a multiple laser mode to an optical amplifier fiber 22, An optical amplifier fiber 22 amplifies a laser mode signal. The amplified laser mode signal is sent to a phase modulator 34 connected with the optical fiber. An output from the phase modulator is sent to receiving interferometer 36, which has a specified pass in balance, and analyzes the respective frequency changes of the laser mode signal. A demodulation part 46 is connected with the interferometer 36, receives the output of the interferometer and demodulates the output.
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公开(公告)号：NO983281L
公开(公告)日：1999-02-01
申请号：NO983281
申请日：1998-07-16
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , BELL STEVEN G
Abstract: A system (10) for performing high resolution measurement of frequency variations in multimode fiber laser acoustic sensors having an end-pumped active fiber sensor (16) emitting a plurality of lasing modes, wherein precise frequencies of the lasing modes emitted are dependent upon a strain acting on said acoustic sensor. An optical fiber (14) is connected to the active fiber sensor (16) for transmitting the lasing modes. The optical fiber transmits the multiple lasing modes to an optical amplifier fiber (22) where the lasing mode signals are amplified. The amplified lasing modes signals are then fed through a phase modulator (34) connected to the optical fiber for applying a phase generated carrier on the lasing mode signals. The output from the phase modulator (34) is supplied to a receiving interferometer (36) having a predetermined path imbalance for interferometrically analyzing the frequency shifts of each of the lasing mode signals, wherein the predetermined path imbalance is matched with the longitudinal mode spacing between the lasing modes of the active fiber sensor. A demodulation unit (46) is connected to the receiving interferometer (36) for receiving and demodulating the output of the receiving interferometer to determine the frequency shift incurred by the lasing mode signals, wherein the demodulated frequency shift is proportional to the strain acting on the acoustic sensor. In an alternative embodiment, a plurality of active fiber sensors may be pumped by a single laser light source with their outputs multiplexed together and fed through the receiving interferometer for interferometric analysis of all the signals.
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Patent Agency Ranking
公开(公告)号：CA2240572C
公开(公告)日：2001-09-11
申请号：CA2240572
申请日：1998-07-07
Applicant: LITTON SYSTEMS INC
Inventor： BELL STEVEN G , FREDERICK DONALD A
Abstract: A system for performing high resolution measurement of frequency variations in multimode fiber laser acoustic sensors having an end-pumped ac tive fiber sensor emitting a plurality of lasing modes, wherein precise frequencies of the lasing modes emitted are dependent upon a strain acting on said acoustic sensor. An optical fiber is connected to the active fiber sensor for transmitting the lasing mo des. The optical fiber transmits the multiple lasing modes to an optical amplifier fi ber where the lasing mode signals are amplified. The amplified lasing modes signals are th en fed through a phase modulator connected to the optical fiber for applying a phas e generated carrier on the lasing mode signals. The output from the phase modulator is s upplied to a receiving interferometer having a predetermined path imbalance for interfero metrically analyzing the frequency shifts of each of the lasing mode signals, wherein t he predetermined path imbalance is matched with the longitudinal mode spacing b etween the lasing modes of the active fiber sensor. A demodulation unit is connecte d to the receiving interferometer for receiving and demodulating the output of the re ceiving interferometer to determine the frequency shift incurred by the lasing mode signals, wherein the demodulated frequency shift is proportional to the strain acting on the acoustic sensor. In an alternative embodiment,. a plurality of active fiber sensors may be pumped by a single laser light source with their outputs multiplexed toge ther and fed through the receiving interferometer for interferometric analysis of all the signals.
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公开(公告)号：BR9802829A
公开(公告)日：1999-11-23
申请号：BR9802829
申请日：1998-07-31
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , BELL STEVEN G
Abstract: A system (10) for performing high resolution measurement of frequency variations in multimode fiber laser acoustic sensors having an end-pumped active fiber sensor (16) emitting a plurality of lasing modes, wherein precise frequencies of the lasing modes emitted are dependent upon a strain acting on said acoustic sensor. An optical fiber (14) is connected to the active fiber sensor (16) for transmitting the lasing modes. The optical fiber transmits the multiple lasing modes to an optical amplifier fiber (22) where the lasing mode signals are amplified. The amplified lasing modes signals are then fed through a phase modulator (34) connected to the optical fiber for applying a phase generated carrier on the lasing mode signals. The output from the phase modulator (34) is supplied to a receiving interferometer (36) having a predetermined path imbalance for interferometrically analyzing the frequency shifts of each of the lasing mode signals, wherein the predetermined path imbalance is matched with the longitudinal mode spacing between the lasing modes of the active fiber sensor. A demodulation unit (46) is connected to the receiving interferometer (36) for receiving and demodulating the output of the receiving interferometer to determine the frequency shift incurred by the lasing mode signals, wherein the demodulated frequency shift is proportional to the strain acting on the acoustic sensor. In an alternative embodiment, a plurality of active fiber sensors may be pumped by a single laser light source with their outputs multiplexed together and fed through the receiving interferometer for interferometric analysis of all the signals.
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公开(公告)号：NO983281A
公开(公告)日：1999-02-01
申请号：NO983281
申请日：1998-07-16
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , BELL STEVEN G
CPC classification number: G01H9/004
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公开(公告)号：CA2240572A1
公开(公告)日：1999-01-31
申请号：CA2240572
申请日：1998-07-07
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , BELL STEVEN G
Abstract: A system for performing high resolution measurement of frequency variations in multimode fiber laser acoustic sensors having an end-pumped active fiber sensor emitting a plurality of lasing modes, wherein precise frequencies of the lasing modes emitted are dependent upon a strain acting on said acoustic sensor. An opt ical fiber is connected to the active fiber sensor for transmitting the lasing modes. The optical fiber transmits the multiple lasing modes to an optical amplifier fiber where the lasing mode signals are amplified. The amplified lasing modes signals are then f ed through a phase modulator connected to the optical fiber for applying a phase ge nerated carrier on the lasing mode signals. The output from the phase modulator is suppl ied to a receiving interferometer having a predetermined path imbalance for interferometr ically analyzing the frequency shifts of each of the lasing mode signals, wherein the predetermined path imbalance is matched with the longitudinal mode spacing betwe en the lasing modes of the active fiber sensor. A demodulation unit is connected to the receiving interferometer for receiving and demodulating the output of the receiv ing interferometer to determine the frequency shift incurred by the lasing mode sign als, wherein the demodulated frequency shift is proportional to the strain acting on the acoustic sensor. In an alternative embodiment,. a plurality of active fiber sens ors may be pumped by a single laser light source with their outputs multiplexed together and fed through the receiving interferometer for interferometric analysis of all the sig nals.
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公开(公告)号：NO983281D0
公开(公告)日：1998-07-16
申请号：NO983281
申请日：1998-07-16
Applicant: LITTON SYSTEMS INC
Inventor： FREDERICK DONALD A , BELL STEVEN G
Abstract: A system (10) for performing high resolution measurement of frequency variations in multimode fiber laser acoustic sensors having an end-pumped active fiber sensor (16) emitting a plurality of lasing modes, wherein precise frequencies of the lasing modes emitted are dependent upon a strain acting on said acoustic sensor. An optical fiber (14) is connected to the active fiber sensor (16) for transmitting the lasing modes. The optical fiber transmits the multiple lasing modes to an optical amplifier fiber (22) where the lasing mode signals are amplified. The amplified lasing modes signals are then fed through a phase modulator (34) connected to the optical fiber for applying a phase generated carrier on the lasing mode signals. The output from the phase modulator (34) is supplied to a receiving interferometer (36) having a predetermined path imbalance for interferometrically analyzing the frequency shifts of each of the lasing mode signals, wherein the predetermined path imbalance is matched with the longitudinal mode spacing between the lasing modes of the active fiber sensor. A demodulation unit (46) is connected to the receiving interferometer (36) for receiving and demodulating the output of the receiving interferometer to determine the frequency shift incurred by the lasing mode signals, wherein the demodulated frequency shift is proportional to the strain acting on the acoustic sensor. In an alternative embodiment, a plurality of active fiber sensors may be pumped by a single laser light source with their outputs multiplexed together and fed through the receiving interferometer for interferometric analysis of all the signals.
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