Q-switched oscillator seed-source for MOPA laser illuminator method and apparatus
First Claim
1. A method comprising:
- providing a first optical gain fiber having a first optical pump source;
generating a seed signal having a Q-switched-pulsed-laser temporal shape using the first optical gain fiber by optically switching using an M-by-N-way optical switch, where M is an integer having a value of at least one, and N is an integer having a value of at least two;
coupling pump light from the first optical pump source into the first optical gain fiber through the optical switch but not coupling laser feedback light through the optical switch when the optical switch is in a first connection state, wherein the generating of the seed signal includes coupling laser feedback light through the optical gain fiber and through the optical switch when the optical switch is in a second connection state;
providing a second optical gain fiber having a second optical pump source; and
amplifying the Q-switched pulsed-laser seed signal in the second optical gain fiber to obtain an output beam having an energy of at least one milliJoule (1 mJ).
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Abstract
An apparatus, method and system that uses a Q-switched laser or a Q-seed source for a seed pulse signal having a controlled high-dynamic-range amplitude that avoids and/or compensates for pulse steepening in high-gain optical-fiber and/or optical-rod amplification of optical pulses. Optionally, the optical output is used for LIDAR or illumination purposes (e.g., for image acquisition). In some embodiments, well-controlled pulse shapes are obtained having a wide dynamic range, long duration, and not-too-narrow linewidth. In some embodiments, upon the opening of a Q-switch in an optical cavity having a gain medium, the amplification builds relatively slowly, wherein each round trip through the gain medium increases the amplitude of the optical pulse. Other embodiments use quasi-Q-switch devices or a plurality of amplitude modulators to obtain Q-seed pulses. These configurations provide optical pulses having wide dynamic ranges that ameliorate problems of pulse steepening, non-linear spectral broadening and the like in very-high-power MOPA devices.
150 Citations
36 Claims
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1. A method comprising:
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providing a first optical gain fiber having a first optical pump source; generating a seed signal having a Q-switched-pulsed-laser temporal shape using the first optical gain fiber by optically switching using an M-by-N-way optical switch, where M is an integer having a value of at least one, and N is an integer having a value of at least two; coupling pump light from the first optical pump source into the first optical gain fiber through the optical switch but not coupling laser feedback light through the optical switch when the optical switch is in a first connection state, wherein the generating of the seed signal includes coupling laser feedback light through the optical gain fiber and through the optical switch when the optical switch is in a second connection state; providing a second optical gain fiber having a second optical pump source; and amplifying the Q-switched pulsed-laser seed signal in the second optical gain fiber to obtain an output beam having an energy of at least one milliJoule (1 mJ). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus comprising:
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a Q-switched seed laser having a first pump source and a first optical gain fiber configured to output a Q-switched pulsed-laser seed signal, wherein the Q-switched seed laser includes a first optical gain fiber and an M-by-N-way optical switch, where M is an integer having a value of at least one, and N is an integer having a value of at least two, wherein the optical switch couples pump light from the first optical pump source into the first optical gain fiber through the optical switch but does not couple laser feedback light through the optical switch when the optical switch is in a first connection state, and wherein the optical switch couples laser feedback light through the first optical gain fiber and through the optical switch when the optical switch is in a second connection state; and a second optical gain fiber having a second optical pump source and operatively coupled to receive light from the Q-switched seed laser and operatively configured to amplify the Q-switched pulsed-laser seed signal in the second optical gain fiber to obtain an output beam having an energy of at least one milliJoule (1 mJ). - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. An apparatus comprising:
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a pulsed Q-seed source having a light source configured to output a Q-seed signal pulse having a temporal shape that, for at least the leading edge of the Q-seed signal pulse, substantially matches a temporal shape of a leading edge of a Q-switched laser pulse, wherein the pulsed Q-seed source includes a Q-switched laser that includes a gain medium within a lasing cavity, a first optical pump source, and a 1×
N electrically controlled optical switch as a Q-switch in the cavity where N is at least two, wherein the optical switch includes a first state that optically couples pump light from the first optical pump source to the gain medium while blocking signal lasing in the cavity and a second state that permits signal lasing in the cavity; andan optical gain fiber having a second pump source and operatively coupled to the pulsed Q-seed source and configured to amplify the Q-seed signal pulse in the optical gain fiber to obtain an output beam having an energy of at least one milliJoule (1 mJ). - View Dependent Claims (19, 20, 21, 22, 23, 24, 27)
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25. An apparatus comprising:
a Q-switched laser that includes a gain medium within a lasing cavity, an optical pump source, and a 1×
N electrically controlled optical switch as a Q-switch in the cavity, wherein the optical switch has a plurality of states including a first state that optically couples light from the optical pump source to the gain medium while blocking signal lasing in the cavity and a second state that permits signal lasing in the cavity while blocking pump light from entering the cavity.- View Dependent Claims (26, 28)
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29. An apparatus comprising:
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an optical gain fiber having an optical pump source; means for generating a seed signal having a Q-switched-pulsed-laser temporal shape by coupling pump light from the pump source to the optical gain fiber when the means for generating is in a first optical-connection state and by coupling laser feedback light through the optical gain fiber when the means for generating is in a second optical-connection state; and means for amplifying the Q-switched pulsed-laser seed signal in the optical gain fiber to obtain an output beam having an energy of at least one milliJoule (1 mJ). - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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Specification