QUASI-PHASE-MATCHED STRUCTURES FOR HIGH AVERAGE POWER NONLINEAR OPTICS

QPM involves alternating regions of nonlinear material, such that efficient 3-wave mixing is achieved without conventional phase matching. If a practical implementation of QPM were developed, then harmonic generation (SHG/THG) from CO(2) laser radiation and mid-infrared (mid-IR) pumped optical parametric oscillators and amplifiers (OPOs/OPAs) would be able to produce broadly tunable radiation across the infrared (IR) wavelength spectrum. Previous research programs have demonstrated the feasibility of QPM structures, using crystals with high thermal conductivities and low absorption would be ideal for high average power applications. In addition the structures typically increase the temperature and angular acceptance bandwidths. Cleveland Crystals would explore the development of two different QPM structures:non-monolithic fabricated structures and "twinned" monolithic crystal structures. Both techniques are high risk, high-payoff technologies. HAP CO(2)SHG systems would be studied using numerical/analytic thermo-optical modeling. For both commercial and DOP applications, a CO(2) or mid-IR pump laser combined with a QPM structure could provide a selectable-fixed frequency, limited or broadly tunalbe, HAP IR laser system. HAP CO(2) driven QPM structues could provide the source for various DOD mid-IR systems.