Low-cost and wideband frequency tunable optoelectronic oscillator based on a directly modulated distributed feedback...

A novel scheme to realize a low-cost and wideband frequency tunable optoelectronic oscillator based on a directly modulated distributed feedback (DFB) semiconductor laser is proposed and experimentally demonstrated. In the proposed scheme, neither an external modulator nor an electrical filter is used, and no more than 25 dB of the electrical loop gain is required due to the high modulation efficiency of the relaxation oscillation frequency of the DFB laser. Microwave signals with frequency coarsely tuned from 3.77 to 8.75 GHz are generated by changing the bias current and operation temperature of the DFB laser. The single sideband phase noise of the generated 6.97 GHz microwave signal is measured to be -103.6 dBc/Hz at 10 kHz offset.