High-resolution optical frequency domain reflectometry using a charge-pump assisted active linearized DFB laser chirp

We present the generation of a broadband, highly linear laser chirp using a DFB laser. A charge-pump assisted optoelectronic phase locked loop (CP-OPLL) effectively suppresses both sweep non-linearity and phase noise during the laser chirp. A high coherence agile frequency-swept DFB laser source with a bandwidth of 50 GHz in 10 ms is achieved. We achieve a 2 mm (3 mm with a Hanning window) transform-limited spatial resolution in optical frequency domain reflectometry (OFDR) range measurement over an entire 500 m fiber link. The demonstrated configuration is adaptable to nearly any semiconductor laser.