Low-loss Stress-Optic Phase Modulator in Standard Optical Fiber

Low-loss, high-speed phase modulators are a key component for future quantum networks. Standard telecom fibers, such as SMF-28, are well suited to long distance quantum communications due to their low propagation and coupling losses, so it is advantageous to implement phase modulators in the same fiber to minimize losses. Current all-fiber modulators are typically based on slow thermo-optic effects, complex optically controlled schemes, or require specialist fibers [1], [2]. An alternative approach to phase modulation uses the stress-optic effect, where refractive index change is induced by applying stress. This has the potential for fast, near lossless phase modulation. Fast rise time polarization rotation has been demonstrated by applying stress using the thermal expansion of Joule heated electrodes within bespoke optical fibers [3]. However, the inclusion of these electrodes induced additional propagation loss.