Nonlinear Optical Crystals: A Complete Survey

A broadly tunable femtosecond optical parametric generator includes a cavity having a pumping section in which is located a nonlinear crystal selected from the group CTA and RTA, cut for noncritical phasematching. The plane of the optical x axis and or the optical y axis of the crystal is aligned with the axis of the pumping section. A Ti:S laser pumping beam is directed into the pumping section either collinearly or noncollinearly with the pumping section axis and impinges on the crystal to produce signal and idler beams. The laser is tunable to produce OPO output beams between about 1 and 4 μm.

Tunable optical parametric oscillator

Deviations from stoichiometry occurring during the crystal growth of lithium niobate have been studied by 93Nb NMR and by shifts in the ferroelectric transition temperature. The high‐temperature phase equilibria of nonstoichiometric lithium niobate were accurately determined by these techniques together with DTA and crystal‐growth experiments. The congruently melting composition is located at 48.6 mole% Li2O and the solid‐solution region at room temperature extends from 48% to 50% Li2O. The implications of growth at noncongruently melting compositions on the compositional uniformity of lithium niobate are discussed in detail.

Nonstoichiometry and Crystal Growth of Lithium Niobate

This paper reviews progress on tunable optical parametric oscillators. Topics considered include: parametric amplification of Gaussian beams: threshold; tuning techniques, spectral output, and stability; saturation and power output; spontaneous parametric emission; nonlinear materials; and far infrared generation.

Tunable optical parametric oscillators

Since their introduction two years ago, quasi-phase-matched (QPM) optical parametric oscillators (OPOs) have moved into the mainstream of OPO research. This has been made possible by continuing improvements and availability of the microstructured nonlinear material periodically poled lithium niobate (PPLN). Demonstrations of PPLN OPOs now span the range of pulse formats and power levels. The most significant area of development is low-peak-power devices where operation with conventional materials is difficult. In this paper, we describe the current state of this research, including OPOs pumped by high-repetition-rate (>30 kHz) Q-switched diode-pumped solid state lasers, and CW singly resonant OPOs with >3-W output power in the 3-4-/spl mu/m range.

Periodically poled lithium niobate and quasi-phase-matched optical parametric oscillators

The use of LiNbO3 crystals in nonlinear optical experiments has been limited by the lack of long, high‐quality crystals. We have shown that crystals grown from a congruent composition melt are significantly less susceptible to birefringence variations which in the past have limited the useful phase‐matchable lengths of LiNbO3 crystals. Both a birefringence test which directly measures the spatial birefringence of the crystal and a second harmonic generation test were used to evaluate crystals grown from melts of various compositions. Crystals with less than 10−5 variation in birefringence over a length of 4 cm have been obtained repeatably when grown from congruent melts.

Growth of High‐Quality LiNbO3 Crystals from the Congruent Melt

A tunable optical parametric oscillator using a 5145‐A argon laser as a pump and lithium niobate as the nonlinear material is reported. The oscillator is constructed in a manner such that the total multimode power of the pumping laser is useful for pumping the oscillator. Operation far from degenerate, combined with a relatively long crystal, leads to measured bandwidths of oscillation about ten times less than those previously reported.

Visible cw parametric oscillator

Nonlinear Optical Properties of Ba2NaNb5O15 in the Tetragonal Phase

Tunable optical continuous wave parametric oscillator using 5145 angstrom Ar laser pump and lithium niobate as nonlinear material, noting large oscillation bandwidth

J. F. Young

Papers

Growth of High‐Quality LiNbO3 Crystals from the Congruent Melt

Visible cw parametric oscillator

Nonlinear Optical Properties of Ba2NaNb5O15 in the Tetragonal Phase

Visible CW parametric oscillator