Carl J. Buczek

Laser injection locking

The basic principles of laser injection locking are discussed and the status of recent experimental work is reviewed. The subject is introduced by means of appropriate lower frequency and microwave injection-locking circuits. These are used to explore the basic physical phenomena involved and to illustrate the essential role of gain saturation in laser injection locking. Oscillators and below-threshold regenerative amplifiers are discussed to provide a more complete and cohesive picture. Experimental results with a variety of CW and quasi-CW injection-locked amplifiers including unstable resonator geometries are presented. Preliminary results with a novel injection-locked passively Q-switched CO 2 amplifier are also given.

An experimental study of unstable confocal CO 2 resonators

The results of an experimental study to determine the spatial properties of unstable confocal resonator modes and their influence upon both the fractional output coupling and the far-field angular divergence are presented. The radial intensity distributions of the lowest order circulating mode within CO 2 unstable resonators and the corresponding near- and far-field patterns have been measured. The radial profiles exhibit a significantly nonuniform intensity distribution consistent with the results of recent theoretical analysis. The far-field intensity distribution as well as the fractional output coupling have been investigated for a number of unstable confocal resonator geometries. For modes contained within the uniform-gain region of the laser tube, the experimental results are in excellent agreement with Siegmans unstable resonator analysis.

Asymmetric unstable traveling-wave resonators

Experimental data pertaining to the intracavity propagation characteristics, the mode volume dissimilarity, and the fractional output coupling Characteristics associated with the oppositely traveling waves in CO 2 asymmetric unstable ring resonators are reported. Equivalence relations are derived, extending Siegmans unstable resonator analysis to encompass asymmetric traveling-wave geometries. Optical feedback techniques to suppress the oscillation associated with one of the traveling waves are demonstrated to be an effective means of achieving unidirectional ring laser operation.

Magnetic stabilization of the plasma column in flowing molecular lasers

A technique of magnetically stabilizing the position of the plasma column and the resulting inversion region in lower pressure flowing molecular lasers is described. A transverse magnetic field, mutually perpendicular to the discharge axial electric field and the gas flow velocity, is employed to maintain the electrical discharge column parallel with the optic axis. The magnetic stabilization of the discharge is analyzed in terms of the Lorentz forces and the resulting ambipolar drifts of the plasma. A comparison with magnetically stabilized arcs is presented. Supporting experimental data obtained for pure gases and typical laser gas mixtures are given. The operating characteristics of the cross-field CO 2 laser which employs a premixed gas flow channeled transverse to the stabilized discharge to provide convective gas cooling are discussed. The experimental results of a parametric study on the dependence of gain and power output upon gas flow velocities, magnetic field, gas mixtures, and pressure are presented. The operation of the first premixed CW electrically initiated chemical laser has been achieved using cross-field magnetic discharge stabilization. Preliminary operating characteristics of this chemical laser for the 3-µ rotational-vibrational transitions in HF and the 4-µ transitions in DF are presented.