Abstract

Integrated optic frequency shifters which provide wideband electronically tunable frequency shift and output light propagating at a fixed angle, irrespective of the amount of frequency shift, are highly desirable [1,2]. In this paper, a new optical frequency shifting scheme which utilizes noncollinear guided-wave magnetooptic (MO) Bragg diffraction by magnetostatic forward volume waves (MSFVW) in yttrium iron garnet-gadolinium gallium garnet (YIG-GGG) -based optical waveguide structure [3] (Fig. 1) is presented. The constancy of output angle of the frequency-shifted light is facilitated by maintaining a constant wave number for the MSFVW using a dual-tuning mechanism which involves synchronous tuning between the carrier frequency of the RF driving signal (and thus the MSFVW) and the bias magnetic field (Fig.2). In so doing the spatial scan of the frequency-shifted light beam resulting from the tuning of the RF driving frequency is exactly compensated by that resulting from the synchronous tuning of the bias magnetic field. As a result, the Bragg-diffracted light propagates at a constant output angle, irrespective of the RF driving frequency, and thus enables a very large bandwidth be achieved.

© 1993 Optical Society of America