CO2 laser

Abstract

Efficient laser diode excited Thulium (Tm) doped solid state systems, directly matched to a combination band pump transition of Carbon Dioxide (CO 2 ), have matured to the point that utilization of such in combination with CO 2 admits effectively a laser diode pumped CO 2 laser. The laser diode excited Tm solid state pump permits Continuous Wave (CW) or pulsed energy application. Appropriate optical pumping admits catalyzer free near indefinite gas lifetime courtesy of the absence of significant discharge driven dissociation and contamination. As a direct consequence of the preceding arbitrary multi isotopologue CO 2 , symmetric and asymmetric, gas mixes may be utilized without significant degradation or departure from initial mix specifications. This would admit, at raised pressure, a system continuously tunable from ˜9 μm to ˜11.5 μm, or sub picosecond amplification. This methodology offers advantages in regards scalability, pulse energy and power over alternative non linear conversion techniques in access to this spectral region.

1 . An optically pumped CO 2  laser comprising, at least, a laser diode excited Tm solid state laser tuned to the 00 0 0→20 0 1 combination band transition(s) of the CO 2  isotopologue(s) to be optically pumped for lasing purposes; gas cell with desired CO 2  gas mix and pressure internal to a resonant cavity and pump field and CO 2  cavity axis combination methodology;
 CO 2  lases in atmospherically transmissive window within spectral region from ˜9 μm to ˜11.5 μm. 
 
     
     
         2 . An optically pumped CO 2  laser, according to  claim 1 , wherein if the optically pumped CO 2  is at pressure, laser diode pumped solid state system efficiency is not limited by molecular line widths and more relaxed conditions apply;
 at reduced pressure where molecular lines resolve individually multiple rotational vibrational transitions may be pumped thus broadening solid state system interaction bandwidth sufficiently for efficient extraction, achievable with single or multi isotopologue gas mix.   
     
     
         3 . An optically pumped CO 2  laser, according to  claim 1 , wherein the optically pumped CO 2  metastable levels accessible for defined ˜9 μm to ˜11.5 μm lasing include the 00 0 1 and 01 1 1 levels. 
     
     
         4 . An optically pumped CO 2  laser, according to  claim 1 , wherein the Tm solid state pump laser may be CW or pulsed and thus the optically pumped CO 2  lasing may be CW or pulsed. 
     
     
         5 . An optically pumped CO 2  laser, according to  claim 1 , wherein the CO 2  component is optically pumped and thus, above atmosphere to significantly above atmosphere operation is straightforward other than for pressure containment considerations. 
     
     
         6 . An optically pumped CO 2  laser, according to  claim 1 , wherein the CO 2  component admits utilization of atmospheric, or higher, pressure non pumped low gain gas cells intra cavity to suppress ˜4.2 μm to 4.3 μm and ˜15.26 μm transitions if desired or required. 
     
     
         7 . An optically pumped CO 2  laser, according to  claim 1 , wherein the CO 2  component, which absent dissociation and discharge related gas contamination under appropriate optical pump conditions, results in near indefinite gas lifetimes. 
     
     
         8 . An optically pumped CO 2  laser, according to  claim 1 , wherein in the absence of dissociation a catalyzer is not a system requirement. 
     
     
         9 . An optically pumped CO 2  laser, according to  claim 1 , wherein given a laser diode excited Tm solid state pump, then fact that ceramic Tm:YAG has been formed and thus in principle arbitrarily large and shaped Tm:YAG structures can be fabricated in conjunction with a demonstrated ˜4 kJ/liter extraction, coupled with the inherent volume scalability of the optically pumped gas component allows for high energy pulsed applications with output in the ˜9 μm to ˜11.5 μm band; YAG is referenced, but any other suitable solid state host is acceptable. 
     
     
         10 . An optically pumped CO 2  laser, according to  claim 1 , wherein the CO 2  component isotopologue(s) may be admixed with one, or more buffer gases selected from the group consisting of Helium, Argon and Nitrogen. 
     
     
         11 . An optically pumped CO 2  laser, according to  claim 1 , wherein the laser diode excited Tm doped solid state optically pumped molecular CO 2  approach is absent chemical reaction sourced optical pumping, and thus is absent related precursor or product gas handling issues plus any efficiency shortfall attributable to line mismatches 
     
     
         12 . An optically pumped CO 2  laser comprising sustained and preserved multi-CO 2  isotopologue, symmetric and asymmetric, mix capability courtesy of absence of significant optical pump driven dissociation under appropriate conditions. 
     
     
         13 . An optically pumped CO 2  laser according to  claim 12 , wherein the CO 2  component ,which absent dissociation, admits utilization of an arbitrarily proportioned multi isotopologue CO 2  gas mix offering optimal line tunability from ˜9 μm through ˜11.5 μm at moderate pressure and continuous tunability from ˜9 μm through ˜11.5 μm at high pressure. 
     
     
         14 . An optically pumped CO 2  laser, according to  claim 12 , wherein the CO 2  component admits utilization of atmospheric, or higher, pressure non pumped low gain gas cells intra cavity to suppress ˜4.2 μm to 4.3 μm and ˜15.26 μm transitions if desired or required. 
     
     
         15 . An optically pumped CO 2  laser, according to  claim 12 , wherein given spectral tunability a system well suited to remote sensing of agents of interest is enabled. 
     
     
         16 . An optically pumped CO 2  laser, according to  claim 12 , wherein at pressure a system is enabled which is suitable for use for short pulse amplification of ˜10 μm CO 2  laser events into the sub picosecond timescale ( FIG. 3 ), or for compact high energy pulsed extraction. 
     
     
         17 . An optically pumped CO 2  laser, according to  claim 12 , wherein as a result of the feasibility of utilization of asymmetric isotopologues and/or the 01 1 1 excited level the system pressure required for continuous tunability will be 50% or less than that required for the purely symmetric isotopologues. 
     
     
         18 . An optically pumped CO 2  laser, according to  claim 12 , wherein absent dissociation, a catalyzer is not a system requirement. 
     
     
         19 . An optically pumped CO 2  laser comprising a laser diode excited Tm doped solid state optical pump wherein the approach to CO 2  is absent the high voltage switching, discharge electrode erosion and EMI issues of traditional pulse discharge (significantly gain switched) CO 2  lasers. 
     
     
         20 . An optically pumped CO 2  laser, according to  claim 19 , wherein absent high voltage high energy switching and high discharge current related electrode erosion, system mean time between required services will be extended.