T. L. Koch

One-way coherent imaging through a distorting medium using four-wave mixing

A proposal and an analysis are presented for imaging through a distorting medium using field multiplication by four-wave mixing.

Picosecond Carrier Dynamics and Laser Action in Optically Pumped Buried Heterostructure Lasers

We report the observation of picosecond optical pulses and unusual pulse structures from optically pumped buried heterostructure semiconductor lasers. A model which considers the hot electron and hole energy distributions dynamically accounts well for our experimental findings. The results are relevant to the problem of the limiting response time of semiconductor lasers.

Analysis and performance of a picosecond dye laser amplifier chain

A mathematical analysis is presented for dye laser amplifier chains used to amplify cw mode‐locked dye laser pulses up to the gigawatt regime. The model permits a discussion of the important aspects of the problem such as gain saturation, pulse shaping, and the optimization of pumping efficiencies. Experimentally, an amplifier chain has been demonstrated which is simple in design and operation without sacrificing high performance. A frequency doubled Q‐switched Nd:YAG oscillator alone is used to longitudinally pump three identical Brewster cells with the same flowing dye solution in each. The amplifier boosts the output of a synchronously mode‐locked dye laser to obtain ∼0.5 mJ≲1 psec pulses over a ∼400 A bandwidth. These pulses are suitable for efficient Raman shifting, frequency mixing, and continuum generation to vastly extend the spectral range of the system. Some experimental results are presented to support the mathematical model.

Gain saturation of a picosecond dye laser amplifier chain

Abstract A three stage Nd:YAG pumped dye laser amplifier chain has been constructed using longitudinal pumping in all three stages. Contrary to common practice, longitudinal pumping is employed to provide high small signal gains (⪆ 10 5 in a single stage) with better beam homogeneity and easier alignment than transversely pumped systems. A simple mathematical model is described for the gain saturation of picosecond amplifiers which includes the effect of angular hole burning. Experimental results are in good agreement with the model. The theory represents a substantial improvement relative to sampler two level saturation models.

Ultrafast magnetophotoconductivity of semi-insulating gallium arsenide

The speed of opto‐electronic switches is increased or decreased by the application of a magnetic field. This is achieved by inducing a carrier drift toward or away from the semiconductor surface, resulting in the enhancement or suppression of surface recombination. We establish that surface recombination plays a major role in determining the speed of the opto‐electronic switch.

Analysis And Performance Of A Picosecond Dye Laser Amplifier Chain

Design considerations are discussed for a simple, easy to use and relatively efficient high gain dye laser amplifier chain for CW mode-locked dye lasers. The amplifier boosts the output of a synchronously mode-locked dye laser to obtain ≈005 mj, ≤ 1 psec pulses over a ≈ 400 Å bandwidth. These pulses are suitable for efficient Raman Shifting, frequency mixing and continuum generation to vastly extend the spectral range of the system. Our amplifier is pumped by a frequency doubled Nd:YAG oscillator only, which longitudinally pumps three identical brewster cells with the same flowing dye solution in each. Contrary to popular belief, high small signal gains (≥ 105) are easily attained in a single stage with longitudinal pumping, with better beam homogeneity and easier alignment than transverse pumping. Gain saturation measurements are presented which agree well with calculations. Factors which relax the pump timing sensitivity are examined. The importance of gain saturation for both efficient amplification and for amplitude stability is also discussed. The need for isolated amplifier stages is stressed and optimal amplifier cell areas for a given stage are calculated.