Compact dynamic optical isolator based on tandem phase modulators.

Abstract

Non-magnetic dynamic optical isolators, constructed from modulators, provide a complementary metal oxide semiconductor (CMOS)-compatible approach to optical isolation in integrated photonics. The size of these isolators is strongly constrained by both the frequency and strength of optical modulation. Recent developments in modulators have indicated that large modulation strength, with a magnitude refractive index modulation up to unity, may be possible at gigahertz modulation frequency. In this Letter, we show that a previously proposed dynamic isolator design, based on tandem modulators, can be modified to take advantage of the possibility of such large modulation strength. Compared with the previously proposed tandem modulator design, our modification can lead to significant reduction of the device length without the need to increase modulation frequency.