Cavity-enhanced harmonic generation in silicon rich nitride photonic crystal microresonators

We report second and third harmonic generation in photonic crystal cavities fabricated in a suspended silicon-rich nitride membrane under resonant continuous-wave excitation at telecom wavelength. Two-dimensional photonic crystal cavities with a far-field optimized line-width modulated design were employed. A quality factor at fundamental wavelength as high as Q = 1.3 × 104 and a coupling efficiency ηc ≈ 30% enabled us to exploit the cavity field enhancement to achieve the generation efficiencies ρSH = (4.7 ± 0.2) × 10−7 W−1 and ρTH = (5.9 ± 0.3) × 10−5 W−2. The absence of saturation effects at high power and the transparency of the device at the second harmonic wavelength suggest the absence of two-photon absorption and related detrimental effects.