Optical switching at 1.55  μ m in silicon racetrack resonators using phase change materials

An optical switch operating at a wavelength of 1.55 μm and showing a 12 dB modulation depth is introduced. The device is implemented in a silicon racetrack resonator using an overcladding layer of the phase change data storage material Ge2Sb2Te5, which exhibits high contrast in its optical properties upon transitions between its crystalline and amorphous structural phases. These transitions are triggered using a pulsed laser diode at λ = 975 nm and used to tune the resonant frequency of the resonator and the resultant modulation depth of the 1.55 μm transmitted light.