Optical pulse source with increased peak power

Abstract

In at least one embodiment time separated pulse pairs are generated, followed by amplification to increase the available peak and/or average power. The pulses are characterized by a time separation that exceeds the input pulse width and with distinct polarization states. The time and polarization discrimination allows easy extraction of the pulses after amplification. In some embodiments polarization maintaining (PM) fibers and/or amplifiers are utilized which provides a compact arrangement. At least one implementation provides for seeding of a solid state amplifier or large core fiber amplifier with time delayed, polarization split pulses, with capability for recombining the time separated pulses at an amplifier output. In various implementations suitable combinations of bulk optics and fibers may be utilized. In some implementations wavelength converted pulse trains are generated. A method and system of the present invention can be used in time domain applications utilizing multiple beam paths, for example spectroscopy.

What is claimed is: 
     
         1 . A pulsed laser system, comprising:
 an input providing time separated pulses having a temporal delay therebetween, each pulse having a different polarization state; and   a single medium in which said time separated pulses propagates, wherein a peak power and energy of each pulse is sufficiently low to avoid substantial distortion of a pulse output from said medium, wherein the power of the time separated pulses, if combined in said medium without said temporal delay, would exceed a non-linear threshold of said medium,   wherein said system is configured such that the time separated pulses output from said medium propagate in separate optical paths providing for synchronization of time separated pulses.   
     
     
         2 . The pulsed laser system of  claim 1 , comprising a wavelength converter disposed in a first optical path and receiving a first pulse from said medium, and converting the wavelength of said first pulse from said medium to a first converted wavelength. 
     
     
         3 . The pulsed laser system  claim 2 , wherein said system comprises a second wavelength converter in a second optical path and receiving a second pulse from said medium, and converting the wavelength of said second pulse from said medium to a second converted wavelength. 
     
     
         4 . The pulsed laser system of  claim 1 , wherein said input comprises a gain medium comprising substantially all-fiber and no bulk optical components in said gain medium. 
     
     
         5 . The pulsed laser system of  claim 4 , wherein said input comprises a delay generator, and at least a portion of said delay generator comprises bulk optics. 
     
     
         6 . A pulsed laser system, comprising:
 a seed source generating a pulse;   a polarization splitter to split said pulse into different polarization states, thereby forming polarization split pulses;   a delay generator which receives said polarization split pulses and generates time separated pulses, said delay generator configured to control a temporal relationship between said polarization split pulses and to provide a temporal delay therebetween, each pulse having a different polarization state;   a single medium in which said time separated pulses having said different polarization states propagate, wherein a peak power and energy of each of said time separated pulses is sufficiently low to avoid substantial distortion of a pulse output from said medium, wherein the power of the time separated pulses, if combined in said medium without said temporal delay, would exceed a non-linear threshold of said medium; and   a combiner that receives said time separated pulses from said medium and substantially re-combines the time separated pulses and compensates said temporal delay to form an output pulse having increased peak power,   wherein said polarization splitter and said delay generator introduce delay larger than duration of said pulse generated by said seed source.   
     
     
         7 . The pulse laser system of  claim 6 , wherein said polarization splitter comprises PM fiber operably arranged such that an input beam to said PM fiber is coupled into both the fast and slow axes of said PM fiber, via fiber splicing, and said polarization splitting is controlled by angular offset in splicing. 
     
     
         8 . A pulse laser system, comprising,
 a seed source generating an optical pulse;   an input providing polarization split optical pulses, each polarization split pulse having a different polarization state; and   one, or a series, of optical fibers at least one of which comprises a gain fiber having a gain medium, said time separated pulses propagating in said one or series of optical fibers and exhibiting variable and increasing temporal separation in at least one portion therein, said time separated pulses having said different polarization states, wherein a peak power and energy of each of said time separated pulses is sufficiently low to avoid substantial distortion of a pulse output from said one or series of optical fibers, wherein the power of the time separated pulses, if combined in said gain medium without said temporal separation, would produce substantial degradation of output pulse quality; and   a combiner that receives said time separated pulses from said one or series of optical fibers and substantially re-combines the time separated pulses and compensates said temporal delay to form an output pulse having increased peak power.   
     
     
         9 . The pulse laser system of  claim 8 , wherein said input is integral with said one or series of optical fibers and said polarization split pulses are generated therein. 
     
     
         10 . The pulse laser system of  claim 8 , wherein pulses provided by seed source are linearly polarized. 
     
     
         11 . The pulse laser system of  claim 8 , wherein pulses provided by seed source are circularly polarized, elliptically polarized, or non-polarized, depolarized or partially polarized. 
     
     
         12 . The pulse laser system of  claim 8 , wherein said input comprises a PM fiber pigtail optically connected to said seed source and arranged to receive said pulse, and operably arranged such that power is distributed in each of the fast and slow axes of said one or more fibers disposed downstream from said input. 
     
     
         13 . The pulse laser system of  claim 8 , wherein said input is disposed downstream from said seed source. 
     
     
         14 . The pulse laser system of  claim 8 , wherein said input comprises a polarization splitter and a delay generator. 
     
     
         15 . The pulse laser system of  claim 8 , wherein said input comprises a linearly polarized beam, and wherein at least one fiber is a PM fiber, said input and said one or series of optical fibers operably arranged such power is distributed in each of the fast and slow axes of said PM fiber. 
     
     
         16 . The pulse laser system of  claim 8 , wherein said gain fiber is a PM amplifier fiber. 
     
     
         17 . The pulse laser system of  claim 8 , wherein at least one fiber supports multiple modes. 
     
     
         18 . The pulse laser system of  claim 8 , wherein at least one fiber is single mode. 
     
     
         19 . The pulse laser system of  claim 8 , wherein said one or series of fibers comprises: a large mode multimode amplifier fiber (MMFA) capable of providing substantially fundamental mode output, large core leakage channel amplifier fiber (LCF design), photonic crystal amplifier fiber (PCF design),   
     
     
         20 . The pulse laser system of  claim 8 , wherein if the power of said time separated pulses were combined in said medium without said temporal delay, a non-linear threshold of said medium would be exceeded, and one or more nonlinear effects would substantially degrade output pulse quality. 
     
     
         21 . The pulse laser system of  claim 8 , wherein if the power of said time separated pulses were combined in said medium without said temporal delay, output pulse quality would be substantially degraded by pulse breakup or noise. 
     
     
         22 . The pulse laser system of  claim 8 , wherein one or both of polarization splitting or delay generation are implemented in an all-fiber arrangement, including splices between fibers. 
     
     
         23 . The pulse laser system of  claim 8 , wherein said series of fibers are joined by fiber splices. 
     
     
         24 . A pulse laser system, comprising,
 a seed source generating a linearly polarized optical pulse;   one or more optical fibers, including at least one polarization maintaining (PM) optical fiber optically connected to said seed source and operably arranged to generate polarization split optical pulses having different polarization states and a temporal delay therebetween; and   a combiner that receives said time separated pulses as output from said one or more optical fibers, and substantially re-combines the time separated pulses and compensates said temporal delay to form an output pulse having increased peak power,   wherein a peak power and energy of each of said time separated pulses is sufficiently low to avoid substantial distortion of a pulse output from said one or more optical fibers, wherein the power of the time separated pulses, if combined in said one or more fibers without said temporal delay, would substantially degrade output pulse quality.   
     
     
         25 . The pulse laser system of  claim 24 , wherein said seed source comprises a passively mode locked laser. 
     
     
         26 . The pulse laser system of  claim 25 , wherein said passively mode locked laser includes a fiber gain medium. 
     
     
         27 . The pulse laser system of  claim 24 , wherein passively mode locked fiber laser comprises PM fiber. 
     
     
         28 . The pulse laser system of  claim 24 , wherein said at least one PM fiber comprises a PM fiber amplifier. 
     
     
         29 . The pulse laser system of  claim 24 , wherein at least one of said one or more optical fibers comprises a gain medium.