Tunable frequency upconversion based on a directly modulated DFB-LD and FP-LD injection

We show a simple,convenient,and cost-effective scheme for tunable frequency upconversion at millimeterwave band without a local oscillator. By launching a 2.5-Gb/s directly modulated baseband signal into a Fabry–Perot laser diode(FP-LD),the mode of the FP-LD is locked by the high-order sideband of the injected signal. The beating frequency of the injection-locked mode and the injected signal can generate upconversion subcarriers. In our experiment,tunable frequency subcarriers of 28.4,29.3,and 30.5 GHz are obtained without any radio-frequency local oscillator. The single sideband phase noises of-83.88,-76.36,and-78.54 dBc/Hz @ 10 kHz(at 28.4-,29.3-,and 30.5-GHz subcarriers,respectively) are shown. The proposed scheme has potential to generate much higher frequency carriers.