Realizing 60 GHz narrow-linewidth photonic microwaves with very low RF driving power

In this letter, we realize tunable (up to 60 GHz) microwave signal generation with low phase noise (−82.7 dBc Hz−1 with an offset of 10 kHz at 60 GHz) and low RF driving power (≤2.0 dBm). A monolithically integrated semiconductor dual wavelength laser diode is used, where an enhanced  −3 dB bandwidth of up to 30 GHz is realized with a PP resonance effect. By using an RF signal (ƒmod  =  ƒ/2) to directly modulate the distributed feedback laser section, the dual wavelengths of the laser diode can be locked by the generated sidebands (±2nd order), the beating of which generates a stable microwave signal with high purity.