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

Patent metadata

Field	Value
Publication number	US-12512643-B2
Application number	US-202318107524-A
Country	US
Kind code	B2
Filing date	Feb 9, 2023
Priority date	Aug 18, 2022
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

Abstract

A tunable microwave source based on dual-wavelength lasing of a single optical whispering gallery microcavity includes 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; an optical filter for optical signal and noise filtration; and a high-speed detector for generating a tunable microwave signal with narrow bandwidth. The dual-wavelength laser includes a pump source, the optical whispering gallery microcavity, an optical waveguide or a tapered optical fiber, a microcavity substrate, and a gold electrode pair. The frequency spacing of the dual-wavelength lasing is tuned by adjusting the external voltage of the gold electrode pair.

First claim

What is claimed is:

1 . 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.

2 . The tunable microwave source according to claim 1 , wherein the microcavity substrate is made from lithium niobate, silicon, silicon dioxide, silicon nitride, silicon carbide, group IV semiconductor materials and their compounds, group III-V compounds, group II-VI compounds, group IV-VI compounds, organic semiconductor materials or sapphire.

3 . The tunable microwave source according to claim 1 , wherein gain media of the single optical whispering gallery microcavity are rare earth ions or quantum dots; the single optical whispering gallery microcavity is a microdisk, deformed, microring or racetrack-shaped resonator.

4 . The tunable microwave source according to claim 1 , wherein all the quasi-degenerate polygon modes at pump wavelength and lasing wavelength have characteristics that an intrinsic frequency difference between quasi-degenerate pump and lasing modes is in a range of several GHz to THz magnitude, where a difference between radial quantum number and azimuthal quantum number of the quasi-degenerate polygon modes is fixed and is determined by the intrinsic frequency and a corresponding quantum number, so that mode field geometric distribution of each of the quasi-degenerate lasing and pump modes is close to each other, but with a π phase difference, thereby a spatial overlap factor between the quasi-degenerate pump mode and the quasi-degenerate lasing mode is high and close to each other, leading to a high suppression of mode gain competition and in turn formation of the stable dual-wavelength laser.

5 . The tunable microwave source according to claim 1 , wherein the quasi-degenerate polygon modes with similar spatial distribution characteristics are generated by recombination of the WGMs which is caused by mode weak perturbation of the single optical whispering gallery microcavity, the perturbation has little effect on a quality factor of the WGMs, maintaining the inherent high quality factor of at least 106 in the WGMs; the quasi-degenerate polygon modes with similar spatial distribution characteristics are far away from an edge of the microcavity, encounter a small surface scattering loss, and have quality factors of at least 106, thereby obtaining the laser with narrow linewidth.

6 . The tunable microwave source according to claim 1 , wherein by changing a diameter of the single optical whispering gallery microcavity, a coupling distance between the optical waveguide or tapered optical fiber and the single optical whispering gallery microcavity, and a wavelength of the pump light, a polygon shape of the quasi-degenerate polygon modes with similar spatial distribution characteristics is selectively excited, so as to obtain a different frequency spacing of dual-wavelength laser, thereby controlling a working range of the dual-wavelength laser.

7 . The tunable microwave source according to claim 1 , wherein the quasi-degenerate polygon modes with similar spatial distribution characteristics in the laser wavelength have a small spatial distribution difference, so that a local refractive index is changed by means of electro-optic effect, thermo-optic effect or plasma dispersion physical effect, so as to tune the frequency spacing of dual-wavelength.

Assignees

• Univ East China Normal

Inventors

• Cheng Ya
• Gao Renhong
• Guan Jianglin
• Fu Botao
• Li Chuntao
• Wang Min
• Li Minghui

Classifications

• H01S3/06704

  Housings; Packages · CPC title

• H01S3/107

  using electro-optic devices, e.g. exhibiting Pockels or Kerr effect {(H01S3/1061, H01S3/1063, H01S3/1065 take precedence)} · CPC title

• H01S3/094053

  Fibre coupled pump, e.g. delivering pump light using a fibre or a fibre bundle · CPC title

• G02F1/39

  for parametric generation or amplification of light, infrared or ultraviolet waves · CPC title

• H01S3/06754

  Fibre amplifiers (H01S3/06708 takes precedence) · CPC title