Optoelectronic mixing with photoconductive switch and semiconductor mode-locked laser

摘要

We demonstrate an optoelectronic mixer based on an ultrafast InGaAs photoconductive switch and a mode-locked semiconductor laser diode. The advantage of the switch is its relatively flat response curve in a wide frequency range of 1–67 GHz. The InP based quantum-dash mode-locked laser emitting in the 1550 nm wavelength range, serves as the source of the local oscillator frequency of 24.5 GHz. The proposed scheme is taking advantage of the low-linewidth of the pulsed laser source and can be used as a heterodyne mixer at the receiver side of a Radio-over-fiber network’s wireless link. We show the mixing performance through I-Q modulated data-stream downconversion and its improvement when the phase noise of the laser is reduced thanks to an optical feedback loop.