Abstract

Fiber Raman lasers¹ require various intracavity elements such as wavelength selectors, isolators and output couplers. These introduce losses, not only from absorption and reflection, but also from wavefront distortions which can severely reduce coupling into single-mode fibers. We describe here a fiber Faraday rotator which circumvents these loss problems by using the same birefringent single-mode fiber² as the oscillator. The birefringence is essential for maintaining linear polarization and is responsible for the wavelength selectivity of the Faraday rotator. The present device is a 90° rotator which increases the efficiency of pump coupling and feedback and permits continuous variation of the output coupling. Similar devices could be used for tuning, isolators or unidirectional elements.

© 1980 Optical Society of America