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Proceedings Paper

Simple measurement of the coherence function of cw lasers by a photorefractive grating method
Author(s): Peter Pogany; Hans Joachim Eichler
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Paper Abstract

We demonstrate an adjustment-insensitive technique for measuring the squared temporal coherence function of cw, longitudinally multi- and monomode semiconductor lasers, using codirectional two-beam coupling in photorefractive InP:Fe and CdTe:V crystals. The emission spectra of the diodes are measured independently and the coherence functions are also calculated by Fourier transform from the spectra. The photorefractive measurements are in good agreement with these calculations. The coupling of two partially coherent waves in low-speed absorptive photorefractive media is studied. We give an exact explicit solution of the 1D linear coupled wave equation for the beam intensities and for the degree of mutual coherence, which changes during the wave mixing. This change is significant for large input beam intensity ratios but only in second order in the coupling strength for equal input beam intensities. In this latter case for moderate coupling strength the energy transfer between the beams is proportional to the square of the input coherence degree, providing a simple determination of the squared coherence function due to measurement of the signal intensity enhancement as function of the time delay between the beams. The possibility to determine some important characteristic of the emission spectrum from the measured squared coherence function is discussed.

Paper Details

Date Published: 26 May 1999
PDF: 8 pages
Proc. SPIE 3610, Laser Material Crystal Growth and Nonlinear Materials and Devices, (26 May 1999); doi: 10.1117/12.349223
Show Author Affiliations
Peter Pogany, Technische Univ. Berlin (Germany)
Hans Joachim Eichler, Technische Univ. Berlin (Germany)


Published in SPIE Proceedings Vol. 3610:
Laser Material Crystal Growth and Nonlinear Materials and Devices
Kathleen I. Schaffers; Lawrence E. Myers, Editor(s)

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