Parametric oscillation, efficiency

Abstract Optical Parametric Oscillators provide a very efficient source of tunable coherent radiation. The principle of different kinds of OPOs are described. OPOs are used in astronomy for Laser Guide Star systems, and they may be used for other nonlinear optics applications in astrophysics, such as frequency conversion or parametric amplification. 

Enhancement of x2 will lead to improvement (in terms of efficiency per interaction volume) in the following applications up-conversion in the visible or near U.V. of powerful I.R. laser radiation, frequency modulation of a laser carrier beam, optical parametric oscillation and amplification for solid state infrared tunable coherent devices. 

We have described for a number of molecular single crystals the basic principles and techniques which were involved in the optimization of their nonlinear efficiency and crystalline quality. Certainly, other types of molecules or material processing techniques can be used. In particular, it could be worthwile to try and by-pass the difficulty of growing large single crystals for applications which are less demanding in terms of optical quality parametric oscillation. 

D. Artigas and D.T. Reid, Efficient femtosecond optical parametric oscillators based on aperiodically poled nonlinear crystals. Optics Letters 27(10), 851-853 (2002). 

The initial step in the double-resonance scheme is the excitation of a local mode hydrogen stretch vibration localized in a hydrogen halide moiety. In principle, this can be done either at the fundamental or one of the overtones. With presently available Ti sapphire lasers and parametric oscillators (OPOs), it is possible to saturate fundamentals and first overtones, thus ensuring maximum population transfer. Second overtones cannot be pumped as efficiently, but offer enormous discrimination against background and can be used to shift frequencies out of the vacuum ultraviolet and into a more user-friendly part of the ultraviolet. Thus, first and second overtones are very attractive. 

A pulse laser is another excitation source for generating various reactive intermediates efficiently. In the case of pulse lasers, selective excitation of the ground and excited states is easy because laser pulses with various wavelengths can be obtained by harmonic generation with nonlinear crystals. Recent development of a laser utilizing optical parametric oscillation, which emits a variable wavelength, enlarged the scope of study. Thus, two-color two-laser flash photolysis has been adapted to a wide variety of fields [3]. Furthermore, utilization of... 

The one-color experiment was performed with pump and probe pulses of the same photon energy (2.00eV). In this case a synchronously pumped femtosecond optical parametric oscillator was used (see Sect. 2.1.1). At A = 1.3 im the signal wave s maximum output reached more than 400 mW, corresponding to 20% conversion efficiency. The signal wave was frequency-doubled by a BBO crystal (60 mW). By measuring an interferometric autocorrelation... 

We have heretofore had ample discussion of linear optical properties of ZnO and related materials. In this section, the nonlinear processes in ZnO are discussed, a topic that has been investigated in some detail. The research on nonlinear optical properties of semiconductors is motivated by electro-optic devices that can be used in telecommunications and optical computing as efficient harmonic generators, optical mixers, and tunable parametric oscillators, among others. The nonlinear optical properties such as second harmonic generation (SHG), that is, (2(0i, 2(02), and the sum frequency generation (SFG), that is, (materials characterization, particularly surfaces, because the second-order susceptibility coefficient is very sensitive to the change in symmetry (178,179). The crystal should be... 

In a crystalline medium, the parametric gain (2) T2 is propor-tionnal to d2 Ip n-3 and the oscillation condition r2A2>aA where a is the signal residual absorption (dramatically increased by any crystalline defect), d the efficient phase-matched nonlinear susceptibility, n an average refractive index, Ip the pump intensity (limited by the optical damage threshold) and A the effective interaction length (also limited by any source of crystalline disorientation). 

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