Tunable optoelectronic oscillator with an embedded delay-line oscillator for fine steps

Tunable optoelectronic oscillator (OEO) with an embedded delay-line oscillator (EDO) for fine steps is presented. A delay-line oscillator consisting of an amplifier, phase shifter, and electrical delay line is embedded in the general single loop OEO. The oscillation frequency is controlled by the EDO loop phase, which is adjusted by the phase shifter. Without any narrow radio frequency bandpass filter, about 340 MHz tunable range with a fine step of similar to 100 kHz is realized by directly tuning the direct current voltage of the phase shifter for 8 GHz oscillation. We also experimentally demonstrate kappa-band tunable microwave signal generation within 22.18 to 23.32 GHz. The tunable accuracy and tunable range have a better performance compared to other OEO schemes with a fine frequency tunable step. The phase noise of the generated 22.25 GHz microwave signal is -108.7 dBc/Hz at 10 kHz offset. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)