Achieving high sensing resolution using a Microwave Photonic Signal generated by a laser diode with a control cavity
Optics and Lasers in Engineering
Laser diodes (LDs) experiencing external optical feedback (OF) are known to demonstrate complex nonlinear dynamics and found various applications. Typical sensing configuration using an LD with OF is called optical feedback interferometry (OFI) that can produce an interferometric-like fringe signal (called OFI fringe) with a fringe resolution as half laser wavelength for displacement measurement. This work uses a dual-cavity OFI and operates the LD at Period-One (P1) state. By optimal configuration for such system, a microwave photonic (MWP) signal can be generated in oscillation form at a very high frequency with its amplitude modulated by an OFI fringe signal. The high frequency component contained in the MWP signal is used for subdivision of an OFI fringe to greatly improve sensing resolution. Both simulation and experiment are conducted to confirm the proposed approach for OFI fringe subdivision.
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