Broad-band (≥20 GHz) laser-diode-based optoelectronic microwave phase shifter

Abstract

We demonstrate a new type of broad-band microwave phase shifter with superior performance at frequencies up to 20 GHz. This is implemented by simply adding an offset voltage prior to the loop filter (LF) in a laser-diode-based digital optoelectronic phase-locked loop (OEPLL). Accurate control of the phase of microwave signals with a continuously tunable range exceeding 640 (3.6) is achieved. The phase fluctuation and long-term drift of any desired phase shift are as small as 60.4 and 0.08 , respectively, at 20 GHz. The relative phase instability can be maintained within 0.09 while operating in a phase-shiftkeying (PSK) scheme. We also demonstrate accurate control of relative phase difference between dual phase-locked microwave sources using the phase shifter. Our results indicate potential application of this broad-band optoelectronic phase shifter in a phased-array antenna system. Index Terms-Microwave, optoelectronic, phase shifter.

Novel delay-time tunable pulsed laser source

“…Note that the anomalous increasing in tuning error of up to 15 ps at smaller delay-time regime is mainly due to the finite operating bandwidth of the PFD in the phase-tracking circuit. [27] This can be further improved by using a high-speed PFD with ultrashort rising time.…”