Travelling-Wave Optical Parametric Amplification in Gallium Phosphide Integrated Waveguides

We demonstrate integrated optical continuous-travelling-wave parametric amplifiers that significantly surpass the amplification bandwidth of traditional Erbium-Doped Fiber Amplifiers. Using a 5.55-cm-long integrated gallium phosphide waveguide, we achieve up to 35 dB of parametric gain in the small-signal regime, and more than 10 dB of off-chip net gain in the wavelength window spanning approximately 140 nm and centered at 1550 nm, with the maximum value of net gain reaching 25 dB. This is, to our knowledge, the first demonstration of such a large and broadband continuous-wave net gain in a photonic integrated waveguide.