Efficient Frequency Conversion in a Degenerate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>?</mml:mi><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:mn>2</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:mrow></mml:msup></mml:math> Microresonator

Microresonators on a photonic chip could enhance nonlinear optics effects and thus are promising for realizing scalable high-efficiency frequency conversion devices. However, fulfilling phase matching conditions among multiple wavelengths remains significant challenge. Here, we present feasible scheme degenerate sum-frequency that only requires the two-mode condition. When drive signal both near resonance to same telecom mode, an on-chip photon-number efficiency up 42% is achieved, showing broad tuning bandwidth over 250 GHz. Furthermore, cascaded Pockels Kerr optical observed, enabling parametric amplification of distinct in single device. The demonstrated this Letter provides alternative approach future studies communications, atom clocks, sensing, imaging.