RESUMO
Silicon nitride (SiN) waveguides need to be thick to show low dispersion which is desired for nonlinear applications. However, high quality thick SiN produced by chemical vapour deposition (CVD) contains high internal stress, causing it to crack. Crack-free wafers with thick SiN can be produced by adding crack barriers. We demonstrate the use of dicing trenches as a simple single-step method to produce high quality (loss<0.5 dB/cm) crack-free SiN. We show Kerr-comb generation in a ring resonator to highlight the high quality and low dispersion of the waveguides.
RESUMO
We introduce a new principle that enables separate control of the amplitude and phase of an optical carrier, simply by controlling the power of two stimulated Brillouin scattering (SBS) pumps. This technique is used to implement a microwave photonic phase shifter with record performance, which solves the bandwidth limitation of previous gain-transparent SBS-based phase shifters, while achieving unprecedented minimum power fluctuations, as a function of phase shift. We demonstrate 360° continuously tunable phase shift, with less than 0.25 dB output power fluctuations, over a frequency band from 1.5 to 31 GHz, limited only by the measurement equipment.
