Method and apparatus for generating and employing a high density of excited ions in a lasant
First Claim
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1. A method for pumping a lasant including a mode volume having an absorption coefficient, a length along an optic axis, and active ions that are excitable to a metastable excitation state in which excited ions have an effective fluorescence lifetime, the method comprising:
- generating a pumping bean having a high degree of lateral and spatial coherence at a pumping rate ω
p ;
optically pumping with the pumping beam a nonstoichiometric lasant in which the mode volume has an active ion concentration of greater than 1%;
concurrently exciting greater than 1% of the active ions in the mode volume to the metastable excitation state, in which a solitary ion has a fluorescence lifetime τ
f, to induce concentration-dependent depopulation mechanisms corresponding to a parameter B in addition to spontaneous and stimulated emission from the metastable excitation state, such that the inverse of a parameter "a" represents an effective fluorescence lifetime of excited active ions in the metastable excitation state, where parameter "a" is generally expressed as
space="preserve" listing-type="equation">a=(1/τ
.sub.f +ω
.sub.p +B),thereby reducing the effective fluorescence lifetime of excited active ions in the metastable excitation state; and
employing a O-switch to generate from the lasant substantially high peak power pulses having comparable magnitudes over a wide range of pulse repetition frequencies (PRFs) such that a dependence of energy per pulse on a PRF is generally expressed as E1 =E0 (1-e-at), wherein E0 represents the energy per pulse at a PRF that is less than 10 Hz and E1 represents the energy per pulse at a PRF given by the inverse of an interpulse period t.
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Abstract
A laser system uses a broad-area high-power diode laser in cooperation with a nonimaging concentrator, or an unstable resonator semiconductor laser, to end pump a relatively thin, solid-state, highly doped lasant. The laser system generates a very high density of excited ions in the lasant mode volume to produce high peak power pulses having comparable magnitudes over a wide range of pulse repetition frequencies.
48 Citations
24 Claims
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1. A method for pumping a lasant including a mode volume having an absorption coefficient, a length along an optic axis, and active ions that are excitable to a metastable excitation state in which excited ions have an effective fluorescence lifetime, the method comprising:
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generating a pumping bean having a high degree of lateral and spatial coherence at a pumping rate ω
p ;optically pumping with the pumping beam a nonstoichiometric lasant in which the mode volume has an active ion concentration of greater than 1%; concurrently exciting greater than 1% of the active ions in the mode volume to the metastable excitation state, in which a solitary ion has a fluorescence lifetime τ
f, to induce concentration-dependent depopulation mechanisms corresponding to a parameter B in addition to spontaneous and stimulated emission from the metastable excitation state, such that the inverse of a parameter "a" represents an effective fluorescence lifetime of excited active ions in the metastable excitation state, where parameter "a" is generally expressed as
space="preserve" listing-type="equation">a=(1/τ
.sub.f +ω
.sub.p +B),thereby reducing the effective fluorescence lifetime of excited active ions in the metastable excitation state; and employing a O-switch to generate from the lasant substantially high peak power pulses having comparable magnitudes over a wide range of pulse repetition frequencies (PRFs) such that a dependence of energy per pulse on a PRF is generally expressed as E1 =E0 (1-e-at), wherein E0 represents the energy per pulse at a PRF that is less than 10 Hz and E1 represents the energy per pulse at a PRF given by the inverse of an interpulse period t. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A laser system for generating substantially high peak power pulses having comparable magnitudes over a wide range of pulse repetition frequencies, comprising:
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a nonstoichiometric lasant positioned within a resonator cavity and having an absorption coefficient; a substantially high power pumping source that generates light at a wavelength within an absorption bandwidth of the lasant at a pumping rate ω
p ;a greater than 1% concentration in the lasant of active ions excitable to a metastable excitation state in which a solitary excited ion has a fluorescence lifetime of τ
f ;a mode volume within the lasant having a length along an optic axis; an optical coupler that couples the light generated by the pumping source into the mode volume, the mode volume length, active ion concentration, and pumping rate cooperating to excite greater than 1% of the active ions in the mode volume to the metastable excitation state and induce concentration-dependent depopulation mechanisms corresponding to a parameter B in addition to spontaneous and stimulated emission from the metastable excitation state, such that the inverse of a parameter "a" represents an effective fluorescence lifetime of excited active ions in the metastable excitation state, where parameter "a" is generally expressed as
space="preserve" listing-type="equation">"a"=(1/τ
.sub.f +ω
.sub.p +B); anda Q-switch positioned within the resonator cavity for generating high peak power pulses at an energy per pulse E1 at a PRF represented by the inverse of an interpulse period t, in which E1 is generally expressed as E1 =E0 (1-e-at), where E0 represents an energy per pulse at a PRF that is less than 10 Hz. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification