The Output Characteristics Of A KTA Optical Vortex Parametric Oscillator

Optical vortices with a helical wavefront carry the orbital angular momentum(OAM),(?),for each photon,characterized by an azimuthal phase,exp(-(?)(?)?),where?refers to the azimuthal coordinate and(?)is an integer,termed a topological charge.The optical vortices with the above mentioned unique properties have been investigated in many applications,including optical manipulation and trapping,space-division multiplexing telecommunications,super-resolution microscopy,and quantum information.Near infrared 1-3?m is in a human eye safety wave section,in which radiation in this spectral area is mainly absorbed in the eye,rather than in the retina,there is a high light transmittance,laser water communication,human eye safety in smoke The ranging and military fields have important applications.Medium infrared3-5?m is located in the air window band of the atmosphere,with strong penetration of smog,dust,etc.,which has little effect on gas molecule absorption and suspended particle scatter,in gas environmental pollution detection,spectral analysis,laser radar and military Infrared confrontation,etc.has a high application value.The photoplastic oscillator is the most effective way to achieve near-infrared-infrared laser and vortex beam beam.Based on KTA crystals,the optical parameter oscillator composed of KTA crystals,using the type II non-critical phase matching method,by using laser and vortexed to pump,the output characteristics have been studied.The contents of this article mainly include the following:(1)The 1064 Nd:YAG nanosecond laser is used to pump the type II non-critical phase matching KTA photointed oscillator simultaneously achieve high energy,narrow spectrum bandwidth near infrared-infrared laser output.When the pump energy was 20 m J,1.44 m J of 1.535?m and 0.95 m J of 3.468?m laser output was obtained,and the corresponding oblique efficiency was 12.2%and 6.3%.Further,the measured output spectral bandwidth is??_s to 1.3 nm(?5.5 cm^-1)and??_?to 3.4 nm(?2.8 cm^-1).(2)We investigated high energy,narrow spectral bandwidth,near and mid-infrared optical vortex lasers formed by a 1?m optical vortex-pumped KTA optical parametric oscillator.The orbital angular momentum OAM of the pump beam can be selectively transferred to the signal or idler output by changing the reflectivity of the output coupler.With this system,2.04 m J of signal at 1.535?m and 1.75 m J of idler at3.468?m vortex outputs were obtained with a maximum pump energy of 21 m J,corresponding to slope efficiencies of 14%and 10%.The spectral bandwidth of the signal and idler vortex outputs were measured to be??_s?1.3 nm(?5.5 cm^-1)and??_i?1.7nm(?1.4 cm^-1),respectively.