Fig. 3: Characterization of TO and MO responses of the modulator at cryogenic temperatures.
From: An integrated magneto-optic modulator for cryogenic applications
a, TO shift of the spectral response of the microring between 4 and 77 K when no current is injected in the electromagnet. The spectra for both CW (solid lines) and CCW (dashed lines) propagation spectra are shown. b, TO coefficient of the device extracted from the thermal shift of the spectra. For reference, the TO contribution of silica and silicon are also shown. c, MO split of the microring resonance when a current is injected in the electromagnet. The split between CW and CCW resonances (2 × ΔλMO) increases linearly as a function of current magnitude at all temperatures. d, TO shift of the microring resonance when a current is injected in the electromagnet because of local Joule heating. As a guide for the eye, the experimental results have been fitted with a sub-quadratic curve (~Ib where b < 2).
