We report, we believe for the first time, frequency stabilization of a fiber pigtailed laser diode (λ = 0.83 μm) by using a fiber coupler as the frequency discriminator. The fiber coupler has not been modified in any way, e.g., high reflectivity coating on the fiber ends. It acts as a nearly balanced arm Michelson interferometer, of which the peak transmission signal is used for feedback control of the injection current of the laser diode. Using the same optical arrangement, we were also able to measure the vibrational displacement of a piezomirror located at one of the output ports of the fiber coupler.

© 1990 Optical Society of America

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