Tunable microwave source based on dual-wavelength lasing of single optical whispering gallery microcavity

A tunable microwave source based on dual-wavelength lasing of a single optical whispering gallery microcavity, the tunable microwave source comprising:

• a dual-wavelength laser having the single optical whispering gallery microcavity for generating dual-wavelength lasing with adjustable spacing, narrow linewidth and low threshold;
• an optical fiber or waveguide amplifier for optical signal amplification, wherein an input end of the optical fiber or waveguide amplifier is connected with an output end of the dual-wavelength laser;
• an optical filter for optical signal and noise filtration, wherein an input end of the optical filter is connected with an output end of the optical fiber or waveguide amplifier;
• and
• a high-speed detector for generating a tunable microwave signal with narrow bandwidth, wherein an input end of the high-speed detector is connected with an output end of the optical filter, wherein:
• the dual-wavelength laser comprises:
• a pump source;
• the single optical whispering gallery microcavity;
• an optical waveguide or a tapered optical fiber which is directly connected, laterally or vertically coupled with the single optical whispering gallery microcavity through evanescent waves for inputting pump light, outputting lasing, and simultaneously introducing mode weak perturbation, wherein the mode weak perturbation is also able to be achieved by removing an arched boundary of the microcavity corresponding to at most a central angle of 18-degree through linearly cutting, or depositing an arched medium or semiconductor material on an upper surface of the boundary of the microcavity, so as to recombine WGMs (whispering gallery modes) with approximate geometric characteristics and intrinsic frequency to generate quasi-degenerate polygon modes with similar spatial distribution characteristics along a periphery of the microcavity in pump and laser wavelengths but with a π phase difference to suppress mode competition respectively, one of the quasi-degenerate polygon modes comprises at least two quasi-degenerate multi-localized periodic orbits;
• a microcavity substrate;
• and
• a gold electrode pair, wherein a positive electrode and a negative electrode of the gold electrode pair are disposed on an upper surface or a periphery of a cavity body of the single optical whispering gallery microcavity;
• while pumping a quasi-degenerate multi-localized periodic orbit in a wavelength of the pump source, the single optical whispering gallery microcavity generates a dual-wavelength laser which resonates with two quasi-degenerate multi-localized periodic orbits in the laser wavelength and a π-phase difference;
• a spatial overlap of any quasi-degenerate multi-localized periodic orbit in the wavelength of the pump source and the two quasi-degenerate multi-localized periodic orbits with π-phase difference in the laser wavelength is close to 5:5, which is almost exactly overlapping, thereby obtaining a stable dual-wavelength laser and a stable microwave source due to suppression of the mode competition.