US3701956A
Expired / Lapsed
US
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Method of an apparatus for generating ultra-short time-duration laser pulses
Assignee: Northrop Grumman Space and Mission Systems Corp
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Filing: 1971-05-14
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Granted: 1972-10-31
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Expires: 1991-05-14
Abstract
Abstract Both a method and an apparatus are disclosed for generating laser pulses having a time duration on the order of subnanoseconds. These light pulses also have a high output power. They are generated by causing a laser to lase and removing the bulk of the radiation contained in the laser cavity. The remaining radiation or light extends over only a short length of the cavity. This light pulse is mode locked, that is it consists of individual Fourier components of the proper phase so that the short light pulse retains its shape while being amplified again in the laser cavity. This short-duration light pulse may then be made to issue from the cavity. Alternatively, the amplified light may be made to issue as a pulse train or set of pulses. Finally, a single pulse may be utilized for mode locking another laser where the ultra-short time-duration pulse may be amplified again. This may be considered priming and subsequent mode locking of the second laser.
Inventors
- 👤 William W Simmons
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:04
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; H01S3/11; H01S3/1123; H01S3/115; H01S3/05; H01S3/08; H01S3/08054; H01S3/106; H01S3/107; H01S3/1106; H01S3/1109
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
114 words
The method of operating a laser to generate a pulse of radiation having an ultra-short time duration, said method comprising the steps of: a. causing a laser having an optical cavity to lase, thereby substantially filling the cavity with radiation; b. removing radiation contained in the cavity for a predetermined time period less than 2 L/c, where L is the length of the optical cavity and c the velocity of the radiation so that radiation remains in the cavity extending only over a short length of the cavity; c. continuing to amplify the radiation remaining in the cavity to develop an amplified short-duration pulse; and d. removing the amplified pulse from the laser cavity.
Claim 2
Independent Claim
114 words
The method of operating a laser to generate a pulse of radiation having an ultra-short time duration, said method comprising the steps of: a. causing a laser having an optical cavity to lase, thereby substantially filling the cavity with radiation; b. removing radiation contained in the cavity for a predetermined time period less than 2 L/c, where L is the length of the optical cavity and c the velocity of the radiation so that radiation remains in the cavity extending only over a short length of the cavity; c. continuing to amplify the radiation remaining in the cavity to develop an amplified short-duration pulse; and d. removing the amplified pulse from the laser cavity.
Claim 3
Dependent Claim
33 words
The method as defined in claim 1 wherein a portion of each of a series of amplified pulses is removed from the laser, each pulse having a duration short compared to 2 L/c.
Claim 4
Dependent Claim
22 words
The method defined in claim 1 wherein the removed amplified pulse is injected into another laser for injection mode-locking and further amplification.
Claim 5
Independent Claim
227 words
The method of operating a laser to generate a stairstep waveform of radiation, said method comprising the steps of: a. causing a laser having an optical cavity to lase, thereby substantially to fill the cavity with radiation; b. causing the radiation to have a first predetermined direction of polarization; c. causing radiation having a second predetermined direction of radiation to be removed from the cavity; d. removing a portion of the radiation contained in the cavity by rotating the first direction of polarization of the radiation into a third direction of polarization for a predetermined period of time less than 2 L/c, where L is the length of the optical cavity and c is the velocity of the radiation, the third direction of polarization being between the first and the second direction of polarization whereby a portion, but not all of the radiation, is removed from the cavity during the predetermined period of time, whereby a low energy level remains in a portion of the length of the cavity and substantially all of the energy of the radiation remains in the cavity for a period of time of 2 L/c less the predetermined period of time; e. amplifying the radiation remaining in the cavity and having a power of the shape of a stairway flowing within the cavity; and f. removing the amplified radiation from the cavity.
Claim 6
Independent Claim
227 words
The method of operating a laser to generate a stairstep waveform of radiation, said method comprising the steps of: a. causing a laser having an optical cavity to lase, thereby substantially to fill the cavity with radiation; b. causing the radiation to have a first predetermined direction of polarization; c. causing radiation having a second predetermined direction of radiation to be removed from the cavity; d. removing a portion of the radiation contained in the cavity by rotating the first direction of polarization of the radiation into a third direction of polarization for a predetermined period of time less than 2 L/c, where L is the length of the optical cavity and c is the velocity of the radiation, the third direction of polarization being between the first and the second direction of polarization whereby a portion, but not all of the radiation, is removed from the cavity during the predetermined period of time, whereby a low energy level remains in a portion of the length of the cavity and substantially all of the energy of the radiation remains in the cavity for a period of time of 2 L/c less the predetermined period of time; e. amplifying the radiation remaining in the cavity and having a power of the shape of a stairway flowing within the cavity; and f. removing the amplified radiation from the cavity.
Claim 7
Dependent Claim
221 words
Apparatus for generating an ultra-short time-duration pulse, said apparatus comprising: a. an optical cavity defined by a pair of substantially completely reflecting mirrors; b. a laser disposed in said cavity; c. means for pumping said laser to cause it to lase; d. an electro-optical element disposed in said cavity, said element being capable of changing the polarization of light passing therethrough in response to an applied voltage; e. a birefringent element disposed in said cavity, said birefringent element being normally arranged for passing light having a first predetermined polarization from one of said mirrors to the other and being capable of refracting light having a second predetermined polarization out of said cavity; f. a signal generator coupled to said electro-optical element for applying thereto a signal having a predetermined time duration of less than 2 L/c, where L is the distance between said mirrors and c is the velocity of light, whereby the polarization of the light passing through said laser is changed from said first to said second predetermined polarization so as to cause said birefringent element to reflect said light out of said cAvity during said predetermined time duration; and g. continuing to maintain said means for pumping energized, thereby to amplify the light pulse remaining in said cavity having a length short compared to that of said cavity.
Claim 8
Dependent Claim
221 words
Apparatus for generating an ultra-short time-duration pulse, said apparatus comprising: a. an optical cavity defined by a pair of substantially completely reflecting mirrors; b. a laser disposed in said cavity; c. means for pumping said laser to cause it to lase; d. an electro-optical element disposed in said cavity, said element being capable of changing the polarization of light passing therethrough in response to an applied voltage; e. a birefringent element disposed in said cavity, said birefringent element being normally arranged for passing light having a first predetermined polarization from one of said mirrors to the other and being capable of refracting light having a second predetermined polarization out of said cavity; f. a signal generator coupled to said electro-optical element for applying thereto a signal having a predetermined time duration of less than 2 L/c, where L is the distance between said mirrors and c is the velocity of light, whereby the polarization of the light passing through said laser is changed from said first to said second predetermined polarization so as to cause said birefringent element to reflect said light out of said cAvity during said predetermined time duration; and g. continuing to maintain said means for pumping energized, thereby to amplify the light pulse remaining in said cavity having a length short compared to that of said cavity.
Claim 9
Dependent Claim
244 words
Apparatus for generating an ultra-short time-duration pulse, said apparatus comprising: a. an optical cavity defined by a pair of substantially completely reflecting mirrors, said mirrors being so positioned as to form two branches forming an angle with each other; b. a laser disposed in one of said branches; c. means for pumping said laser to cause it to lase; d. an electro-optical element disposed in one of said branches, said element being capable of changing the polarization of light passing therethrough in response to an applied voltage; e. a birefringent prism disposed at the intersection of said branches of said cavity, said prism being normally arranged for refracting light having a first predetermined polarization from one of said branches to the other and being capable of refracting light having a second predetermined polarization out of said cavity; f. a voltage generator coupled to said element for applying thereto a pulse having a predetermined time duration of less than 2 L/c, where L is the length of said cavity and c is the velocity of light, whereby the polarization of the light passing through said element is changed from said first to said second predetermined polarization so as to cause said prism to reflect said light out of said cavity for said predetermined time duration; and g. continuing to maintain said means for pumping energized thereby to amplify the light remaining within said cavity and having a length short compared to that of said cavity.
Claim 10
Dependent Claim
244 words
Apparatus for generating an ultra-short time-duration pulse, said apparatus comprising: a. an optical cavity defined by a pair of substantially completely reflecting mirrors, said mirrors being so positioned as to form two branches forming an angle with each other; b. a laser disposed in one of said branches; c. means for pumping said laser to cause it to lase; d. an electro-optical element disposed in one of said branches, said element being capable of changing the polarization of light passing therethrough in response to an applied voltage; e. a birefringent prism disposed at the intersection of said branches of said cavity, said prism being normally arranged for refracting light having a first predetermined polarization from one of said branches to the other and being capable of refracting light having a second predetermined polarization out of said cavity; f. a voltage generator coupled to said element for applying thereto a pulse having a predetermined time duration of less than 2 L/c, where L is the length of said cavity and c is the velocity of light, whereby the polarization of the light passing through said element is changed from said first to said second predetermined polarization so as to cause said prism to reflect said light out of said cavity for said predetermined time duration; and g. continuing to maintain said means for pumping energized thereby to amplify the light remaining within said cavity and having a length short compared to that of said cavity.
Claim 11
Dependent Claim
29 words
Apparatus as defined in claim 6 wherein said voltage generator develops a second short time-duration pulse for permitting the amplified radiation in said cavity to issue from said cavity.
Claim 12
Dependent Claim
74 words
Apparatus as defined in claim 6 wherein said electro-optical element consists of two Kerr cells, each being disposed in one of said branches and wherein said voltage generator is coupled to one of said Kerr cells, and an additional voltage generator coupled to the other one of said Kerr cells, said additional voltage generator developing a second short time-duration pulse for causing the amplified radiation in said cavity to issue out of said cavity.
Claim 13
Dependent Claim
32 words
Apparatus as defined in claim 6 wherein one of said mirrors is partially transparent, thereby to issue a train of amplified pulses after said light has been refracted out of said cavity.
Claim 14
Dependent Claim
89 words
Apparatus as defined in claim 6 wherein said pulse of predetermined duration has such a voltage that the polarization of the light passing through said element is changed to a value between that of said first and said second predetermined polarization, whereby a portion of all of the light in said cavity remains in said laser while all of the light for said predetermined time duration remains in said cavity to form a mode-phased pulse capable of generating an amplified wave within said cavity of generally stairstep power shape.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-31 | 1976-05-01 | 1976-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-31 | 1980-05-01 | 1980-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-31 | 1984-05-01 | 1984-10-31 | $7700.00 | Window Closed / Lapsed |