Pulsed high-power laser apparatus and methods

A method of operating a laser apparatus comprising (i) first and second seed lasers each emitting an output beam differing in at least one beam characteristic, wherein the first and second seed lasers are (a) both fiber lasers, (b) operated in a complementary fashion, and (c) modulated in accordance with a substantially random frequency, (ii) a coupler for combining the output beams of the seed lasers into a combined beam, the combined beam having a substantially constant power as a function of time, (iii) a first isolator, disposed between the first seed laser and the coupler, positioned to receive the output beam of the first seed laser, (iv) a second isolator, different from the first isolator, disposed between the second seed laser and the coupler, positioned to receive the output beam of the second seed laser, (v) at least one amplifier for increasing a power of the combined beam, thereby forming an amplified beam, (vi) a resonant phase modulator disposed between the coupler and the at least one amplifier, the resonant phase modulator broadening an optical spectrum of the combined beam prior to amplification thereof, (vii) a third isolator, different from the first and second isolators, disposed between the coupler and the at least one amplifier, positioned to receive the combined beam, and (viii) a separator for separating the amplified beam into first and second final output beams based on the at least one beam characteristic, the second final output beam being absorbed by the separator or discarded after separation, wherein (i) the first and second seed lasers, the coupler, the at least one amplifier, the separator, the resonant phase modulator, and the first, second, and third isolators are all fiber-coupled, and (ii) a line width of the at least one amplifier is less than a line width of the combined beam, whereby Brilliouin scattering is suppressed in the at least one amplifier due at least in part to the spectral broadening by the resonant phase modulator, the method comprising:

• operating the first and second seed lasers in a complementary fashion, such that each seed laser emits its output beam only when the other does not;
• combining the output beams of the seed lasers into the combined beam;
• amplifying the combined beam so as to suppress Brilliouin scattering;
• and
• separating the combined beam into the two final output beams differing in the at least one beam characteristic.

A method of printing comprising:

• providing a hydrophilic, ink-receptive lithographic surface having a printing area;
• applying a polar liquid to the printing area for adsorption thereon;
• producing a laser output with an apparatus comprising:
• first and second seed lasers each emitting an output beam differing in at least one beam characteristic, wherein the first and second seed lasers are (i) both fiber lasers, (ii) operated in a complementary fashion, and (iii) modulated in accordance with a substantially random frequency,
• a coupler for combining the output beams of the seed lasers into a combined beam, the combined beam having a substantially constant power as a function of time,
• a first isolator, disposed between the first seed laser and the coupler, positioned to receive the output beam of the first seed laser,
• a second isolator, different from the first isolator, disposed between the second seed laser and the coupler, positioned to receive the output beam of the second seed laser,
• at least one amplifier for increasing a power of the combined beam, thereby forming an amplified beam,
• a resonant phase modulator disposed between the coupler and the at least one amplifier, the resonant phase modulator broadening an optical spectrum of the combined beam prior to amplification thereof,
• a third isolator, different from the first and second isolators, disposed between the coupler and the at least one amplifier, positioned to receive the combined beam, and
• a separator for separating the amplified beam into first and second final output beams based on the at least one beam characteristic, the second final output beam being absorbed by the separator or discarded after separation,
• wherein (i) the first and second seed lasers, the coupler, the at least one amplifier, the separator, the resonant phase modulator, and the first, second, and third isolators are all fiber-coupled, and (ii) a line width of the at least one amplifier is less than a line width of the combined beam, whereby Brilliouin scattering is suppressed in the at least one amplifier due at least in part to the spectral broadening by the resonant phase modulator;
• exposing the liquid-bearing printing area to the laser output in an imagewise fashion, the laser output substantially removing the adsorbed liquid without damaging the printing surface;
• applying ink to the printing area, the ink adhering to the surface only where the polar liquid has been removed by the laser output;
• and
• transferring the ink to a recording medium.

A method of printing comprising:

• providing a hydrophilic, ink-receptive lithographic surface having a printing area;
• applying ink to the printing area for adsorption thereon;
• producing a laser output with an apparatus comprising:
• first and second seed lasers each emitting an output beam differing in at least one beam characteristic, wherein the first and second seed lasers are (i) both fiber lasers, (ii) operated in a complementary fashion, and (iii) modulated in accordance with a substantially random frequency,
• a coupler for combining the output beams of the seed lasers into a combined beam, the combined beam having a substantially constant power as a function of time,
• a first isolator, disposed between the first seed laser and the coupler, positioned to receive the output beam of the first seed laser,
• a second isolator, different from the first isolator, disposed between the second seed laser and the coupler, positioned to receive the output beam of the second seed laser,
• at least one amplifier for increasing a power of the combined beam, thereby forming an amplified beam,
• a resonant phase modulator disposed between the coupler and the at least one amplifier, the resonant phase modulator broadening an optical spectrum of the combined beam prior to amplification thereof,
• a third isolator, different from the first and second isolators, disposed between the coupler and the at least one amplifier, positioned to receive the combined beam, and
• a separator for separating the amplified beam into first and second final output beams based on the at least one beam characteristic, the second final output beam being absorbed by the separator or discarded after separation,
• wherein (i) the first and second seed lasers, the coupler, the at least one amplifier, the separator, the resonant phase modulator, and the first, second, and third isolators are all fiber-coupled, and (ii) a line width of the at least one amplifier is less than a line width of the combined beam, whereby Brilliouin scattering is suppressed in the at least one amplifier due at least in part to the spectral broadening by the resonant phase modulator;
• exposing the ink-bearing printing area to the laser output in an imagewise fashion, the laser output fixing the adsorbed ink on the printing surface;
• applying a polar liquid to the printing area, the polar liquid removing ink that has not received laser exposure;
• and
• transferring the remaining ink to a recording medium.

A printing apparatus comprising:

• a hydrophilic, ink-receptive lithographic surface having a printing area;
• means for applying a polar liquid to the printing area for adsorption thereon;
• means for exposing the liquid-bearing printing area to a laser output in an imagewise fashion, whereby the laser output substantially removes the adsorbed liquid without damaging the printing surface;
• means for applying ink to the printing area such that the ink adheres to the surface only where the polar liquid has been removed by the laser;
• and
• means facilitating transfer of the ink to a recording medium,
• wherein the exposing means comprises:
• first and second seed lasers each emitting an output beam differing in at least one beam characteristic, wherein the first and second seed lasers are (i) both fiber lasers, (ii) operated in a complementary fashion, and (iii) modulated in accordance with a substantially random frequency;
• a coupler for combining the output beams of the seed lasers into a combined beam, the combined beam having a substantially constant power as a function of time;
• a first isolator, disposed between the first seed laser and the coupler, positioned to receive the output beam of the first seed laser;
• a second isolator, different from the first isolator, disposed between the second seed laser and the coupler, positioned to receive the output beam of the second seed laser;
• at least one amplifier for increasing a power of the combined beam, thereby forming an amplified beam;
• a resonant phase modulator disposed between the coupler and the at least one amplifier, the resonant phase modulator broadening an optical spectrum of the combined beam prior to amplification thereof;
• a third isolator, different from the first and second isolators, disposed between the coupler and the at least one amplifier, positioned to receive the combined beam;
• and
• a separator for separating the amplified beam into first and second final output beams based on the at least one beam characteristic, the second final output beam being absorbed by the separator or discarded after separation,
• wherein (i) the first and second seed lasers, the coupler, the at least one amplifier, the separator, the resonant phase modulator, and the first, second, and third isolators are all fiber-coupled, and (ii) a line width of the at least one amplifier is less than a line width of the combined beam, whereby Brilliouin scattering is suppressed in the at least one amplifier due at least in part to the spectral broadening by the resonant phase modulator.

A printing apparatus comprising:

• a hydrophilic, ink-receptive lithographic surface having a printing area;
• means for applying ink to the printing area for adsorption thereon;
• means for exposing the ink-bearing printing area to a laser output in an imagewise fashion, whereby the laser output fixes the adsorbed ink on the printing surface;
• means for applying a polar liquid to the printing area to remove ink that has not received laser exposure;
• and
• means facilitating transfer of the remaining ink to a recording medium,
• wherein the exposing means comprises:
• first and second seed lasers each emitting an output beam differing in at least one beam characteristic, wherein the first and second seed lasers are (i) both fiber lasers, (ii) operated in a complementary fashion, and (iii) modulated in accordance with a substantially random frequency;
• a coupler for combining the output beams of the seed lasers into a combined beam, the combined beam having a substantially constant power as a function of time;
• a first isolator, disposed between the first seed laser and the coupler, positioned to receive the output beam of the first seed laser;
• a second isolator, different from the first isolator, disposed between the second seed laser and the coupler, positioned to receive the output beam of the second seed laser;
• at least one amplifier for increasing a power of the combined beam, thereby forming an amplified beam;
• a resonant phase modulator disposed between the coupler and the at least one amplifier, the resonant phase modulator broadening an optical spectrum of the combined beam prior to amplification thereof;
• a third isolator, different from the first and second isolators, disposed between the coupler and the at least one amplifier, positioned to receive the combined beam;
• and
• a separator for separating the amplified beam into first and second final output beams based on the at least one beam characteristic, the second final output beam being absorbed by the separator or discarded after separation,
• wherein (i) the first and second seed lasers, the coupler, the at least one amplifier, the separator, the resonant phase modulator, and the first, second, and third isolators are all fiber-coupled, and (ii) a line width of the at least one amplifier is less than a line width of the combined beam, whereby Brilliouin scattering is suppressed in the at least one amplifier due at least in part to the spectral broadening by the resonant phase modulator.