Parametric oscillation and mixing

Lasers and Coherent Light Sources

Parametric four-photon generation of picosecond light at high conversion efficiency

A singly resonant parametric oscillator based on proustite has been operated for the first time. The device was pumped by a Q‐switched neodymium (1.065 μm) laser in a noncollinear phase‐matching geometry. The output has been tuned over the wavelength range 1.22–8.5 μm. The idler power was typically ∼100 W in a bandwidth of ∼1 cm−1.

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Singly resonant proustite parametric oscillator tuned from 1.22 to 8.5 μm

We report a very compact, laser diode end-pumped THz laser source, which utilizes two resonators to generate frequency-tunable radiation across the range 1.53-2.82 THz via stimulated polariton scattering (SPS) in a Mg:LiNbO3 crystal. To the best of our knowledge, this THz system operates with the lowest pump power threshold (2.4 W), and highest conversion efficiency (6.45tW average output power at 1.82 THz for 5 W input diode pump power) ever reported for a THz source based on SPS.

Frequency-Tunable THz Source Based on Stimulated Polariton Scattering in ${\rm Mg{:}LiNbO}_{3}$

General relations are derived that describe the rise time of the output power of parametric oscillators driven by a time-dependent pump. Both singly resonant and doubly resonant oscillators are discussed. Results of computer calculations using a Gaussian time envelope for the pump pulse are presented and, in the case of the doubly resonant oscillator, are compared to predictions of a steady-state analysis. Agreement between calculated rise times and published values is good.

/pdf/rise-time-of-pulsed-parametric-oscillators-4qo8gje92p.pdf

Rise time of pulsed parametric oscillators

The finite coherence time of the driving field plays an important role in the rates of energy exchange taking place in nonlinear processes. As a typical example, the problems of the quantum parametric amplifier and frequency converter driven by a fluctuating pump are considered. A closed hierarchy of equations for the moments of the fields is given, which in turn is used for evaluating the average number of photons per mode and the relative variance as functions of time. Significant deviations from the case where the pump field is coherent are found.

/pdf/some-consequences-of-pump-coherence-on-energy-exchange-in-3pmk53k5t2.pdf

Some Consequences of Pump Coherence on Energy Exchange in Nonlinear Optical Processes

The consequences of the deviation from ideal coherence of the driving (pump) field in nonlinear processes are examined. A detailed treatment of the processes of parametric amplification and frequency upconversion is presented. The treatment utilizes two different approximation methods to suit the two different physical situations considered. For slow phase variations of the pump field an adiabatic approach is useful, whereas in the treatment of fast phase variations (the nonadiabatic case) an equation describing the time evolution of the P representation is found to be a good starting point. In this latter case, a closed hierarchy of equations for the moments of the photon number distribution in the signal (or idler) mode is found. In particular, we find that the efficiencies of both the amplification and the upconversion processes are reduced as a result of pump incoherence, the reduction becoming more severe in the highly incoherent case. For the frequency converter, the very nature of the process is modified as compared to the ideal case, and this modification is again of particular significance for the highly incoherent pump. Second-order moments are explicitly calculated and some of the statistical properties of the output signals are examined.

/pdf/the-effect-of-pump-coherence-on-frequency-conversion-and-3ukw7ti4iy.pdf

The effect of pump coherence on frequency conversion and parametric amplification

A new equation of motion, which describes the time evolution of the $P$ representation in the Schr\"odinger picture, is derived. The equation applies to a very general class of Hamiltonians, and thus should be useful in many problems. As a demonstration of the usefulness of this equation, some known results are recovered by its direct application.

Equation of Motion for the P Representation

Measurements of total emitted parametric fluorescence power are presented and used to fix one point on the predicted tuning curve of a parametric oscillator. The method is particularly useful for predicting the tuning curve of infrared pumped parametric oscillators. Experimental results, which verify the usefulness of the technique in a 1.06-μ-pumped oscillator, are presented.

/pdf/parametric-oscillator-tuning-curve-from-observations-of-4j3iipo1xz.pdf

U. Ganiel

Papers

Rise time of pulsed parametric oscillators

Some Consequences of Pump Coherence on Energy Exchange in Nonlinear Optical Processes

The effect of pump coherence on frequency conversion and parametric amplification

Equation of Motion for the P Representation

Parametric oscillator tuning curve from observations of total parametric fluorescence