Phase conjugation

About: Phase conjugation is a research topic. Over the lifetime, 3694 publications have been published within this topic receiving 49099 citations.

Phase conjugation in an amorphous As(2)S(3) thin film.

Abstract: A phase-conjugate wave is generated by degenerate four-wave mixing in an amorphous chalcogenide As2S3 thin film. The time-dependent behaviors of the phase-conjugate wave, the nonlinear absorption coefficient, and the refractive index are treated analytically, and the results are compared with those of experiment. The analyses are based on the rate equations obtained from a simplified energy-band model of amorphous As2S3.

Turbulent statistics of laser beam intensity on ground-to-satellite optical link

Abstract: Numerical simulation of laser beam propagation on space-to- ground and ground-to-space paths is carried out. The simulation is performed for different Cn2 height profile models in dependence on atmospheric turbulence strength. Atmospheric turbulence severely degrades the performance of ground-to-satellite optical links. Using the wave to be passed from satellite to the optical ground station as the reference wave, it is studied the effectiveness of adaptive correction of laser beam propagating from the ground to satellite. Different schemes of adaptive correction are considered, namely, ideal phase conjugation, correction based on information about reference wave phase restored by mean least square procedure. The effectiveness of the correction by adaptive optics to correct wave front distortions caused by atmospheric turbulence, and possibly improving the link budgets from ground to space and vice versa is discussed. We also analyze and discuss the effect of optical scintillation on signal fade and surge.

SBS mirrors for XeCl lasers with a broad spectrum

Abstract: The stimulated Brillouin scattering threshold of focused broad-band XeCl laser radiation depends on the ratio of the coherence length to the Rayleigh range, which is affected by the transverse beam quality. With reduction of the focal length, the threshold decreases first and then reaches a nearly constant value. In addition, the energy reflectivity is increased. On the other hand, pulse shortening occurs and the phase conjugation fidelity is decreased. Separation of single lines from the structured XeCl laser spectrum improves the SBS efficiency.

Detection of ultrasonic vibrations on rough surfaces through the photorefractive effect

Abstract: We present and describe two techniques used for optical detection of ultrasonic signals based on the photorefractive effect. These techniques used the wavefront adaptation properties of the photorefractive effect. In the photorefractive beam combiner, a local oscillator matched to the signal wavefront is created, leading to an homodyne detection system having a large etendue. In the double phase conjugate heterodyne detection system the signal beam wavefront is cleaned by a double phase conjugate mirror and transformed in a plane wave that is sent on a classical heterodyne detection system. Both systems are characterized and used to detect ultrasound.

Mutually pumped phase conjugator for remote identification

Abstract: A universal IFF technique and system utilizes a real-time communication l established between both parties allowing the approximate immediate transferral of digital information with positive direction and identification of both parties achieved. A pump laser emits a first signal at a first position and a remote laser beacon emits a second signal at a second position, both signals at nominally the same wavelength. A MPPCM receives the first signal which establishes a beam fan. The MPPCM and first signal scans about a region of interest to intercept the second signal. The second signal provides a second input signal into the MPPCM so that a two-way phase conjugation signal builds up and lock-on is established.