Frequency Conversion Laser Head

Abstract

A laser assembly is configured with a frequency conversion laser head operative to shift a fundamental frequency of input light to the desired frequency of an output light. The frequency conversion laser head includes a dump means operative to guide an unconverted output light at the fundamental frequency outside the case of the frequency conversion laser head. The dump means is configured with a guide optics operative to couple the output light at the fundamental frequency to a fiber terminating outside the case of the frequency conversion laser head.

1 . A laser assembly comprising a frequency conversion laser head operative to convert a portion of an input light propagating along a transmission light path at a fundamental frequency to a desired frequency of an output light, the frequency conversion laser head having a case, output and dump fibers partially housed in the case and guiding the converted portion at the desired frequency and an unconverted portion of the input light at the fundamental frequency, respectively, outside the case. 
     
     
         2 . The laser assembly of  claim 1 , wherein the frequency conversion laser head includes a non-linear conversion component housed in the case upstream from the output and dump fibers and operative to transform the portion of the input light at the fundamental frequency to the desired frequency of the light. 
     
     
         3 . The laser assembly of  claim 2 , wherein the frequency conversion laser head further comprises a beam splitter mounted in the case downstream from the nonlinear conversion component along and impinged upon by the converted and unconverted portions of the input light, the beam splitter being substantially transparent to the converted portion at the desired frequency propagating further along the transmission path but reflecting the unconverted portion of the light at the fundamental frequency along a dump light path, which extends transversely to the transmission path, towards the dump fiber. 
     
     
         4 . The laser assembly of  claim 3 , wherein the frequency conversion laser head further comprises:
 a mirror located downstream from the beam splitter along the dump light path and configured to reflect the unconverted portion at the fundamental frequency towards the dump fiber, and   a dump focusing optics downstream from the mirror and operative to couple the reflected unconverted portion at the fundamental frequency into the dump fiber.   
     
     
         5 . The laser assembly of  claim 4 , wherein the beam splitter and mirror each are covered with a layer of dielectric material, the beam splitter being configured to tap off a fraction of the converted portion of light at the desired frequency along the light dump path, the minor being transparent to the tapped fraction. 
     
     
         6 . The laser assembly of  claim 5  further comprising a power monitoring unit housed in the case downstream from the mirror along a measuring light path, which deviates from the light dump path, and operative to measure the tapped fraction of the converted portion of light at the desired frequency so as to determine a power of the converted portion. 
     
     
         7 . The laser assembly of  claim 1 , the output fiber is a single mode fiber receiving and launching the converted portion of the output light at the desired frequency at an object to be treated outside the ease. 
     
     
         8 . The laser assembly of  claim 1  further comprising a laser system operative to generate the light at the fundamental frequency which is coupled into the frequency conversion laser head. 
     
     
         9 . The laser assembly of  claim 8 , wherein the laser system and frequency conversion laser head are displaceably fixed to one another. 
     
     
         10 . The laser assembly of  claim 8 , wherein the laser system and frequency conversion laser head are displaceable relative to one another. 
     
     
         11 . The laser assembly of  claim 8 , wherein the laser system is configured as a solid-state laser. 
     
     
         12 . The laser assembly of  claim 8 , wherein the laser system is configured as an all fiber laser. 
     
     
         13 . The laser assembly of  claim 12 , wherein the fiber laser includes at least one fiber block configured with:
 an active multimode (MM) fiber capable of laser action with an emission at a wavelength having the fundamental frequency; and   a single mode (SM) passive fiber butt-spliced to an output end of the MM fiber and extending towards the laser head, the SM fiber being configured so that the light at the fundamental frequency is coupled into the SM passive fiber substantially without distortion and delivered to the frequency conversion laser head.   
     
     
         14 . The laser system of  claim 13  further comprising an optical cavity defined between multiple reflectors and including at least parts of the respective MM and SM fibers. 
     
     
         15 . The laser system of  claim 13 , wherein the SM fiber is directly or indirectly coupled to the frequency conversion laser head. 
     
     
         16 . A frequency conversion laser head operative to convert a portion of light propagating along a transmission light path at a fundamental frequency to a desired frequency, the frequency conversion head comprising a case, output and dump fibers partially housed in the case and guiding the converted portion at the desired frequency and an unconverted portion of the input light at the fundamental frequency, respectively, outside the case. 
     
     
         17 . The nonlinear conversion laser head of  claim 16  further comprising:
 a non-linear conversion component housed in the case and operative to convert the portion of the input light at the fundamental frequency to the desired frequency of the output light, 
 a beam splitter mounted in the case downstream from the nonlinear conversion component along the transmission light path and impinged upon by the light at fundamental and desired frequencies, respectively, the beam splitter being substantially transparent to the light at the desired frequency propagating further along the transmission path but reflecting the light at the fundamental frequency along a dump light path towards the dump fiber. 
 
     
     
         18 . The laser assembly of  claim 17 , wherein the frequency conversion laser head further comprises:
 a mirror located downstream from the beam splitter along the dump light path and configured to reflect the output light at the fundamental frequency towards the dump fiber, and   a dump focusing optics downstream from the mirror and operative to couple the output light at the fundamental frequency into the dump fiber, wherein the beam splitter and mirror each are covered with a layer of dielectric material, the beam splitter being configured to tap off a fraction of the converted portion of light at the desired frequency along the light dump path, the mirror being transparent to the tapped off portion.   
     
     
         19 . The laser assembly of  claim 18  further comprising a power monitoring unit housed in the case downstream from the mirror along a measuring light path, which deviates from the light dump path, and operative to measure the tapped off portion of the output light at the desired frequency so as to determine a power of the output light at the desired frequency. 
     
     
         20 . A method for operating a laser head comprising:
 coupling light at a fundamental frequency into a non-linear element operative to output light at desired and fundamental frequencies, respectively, which are different from one another;   training the output light at a frequency selective element configured to transmit the output light at the desired frequency along a transmission path, and to reflect the output light at the fundamental frequency along a dump path extending transversely to the transmission path;   coupling the transmitted light at the desired frequency into a one fiber located in a case of the laser head and the reflected light at the fundamental frequency into a dump fiber spaced from the one fiber within the case, thereby guiding the light at the desired and fundamental frequencies outside the case.