California Institute of Technology

Government of the United States of America, As Represented by the Secretary of Commerce

Hansuek Lee

Kerry J Vahala

Jiang Li

Tong Chen

Scott A Diddams

Xu Yi

Myoung-Gyun Suh

Scott Diddams

A microwave-frequency source at frequency fcomprises: a dual optical-frequency reference source, an electro-optic sideband generator, an optical bandpass filter, an optical detector, a reference oscillator, an electrical circuit, and a voltage-controlled oscillator (VCO). The sideband generator modulates dual optical reference signals at vand vto generate sideband signals at v&#xb1;nfand v&#xb1;nf. The bandpass filter transmits sideband signals at v+Nfand v&#x2212;Nf. The optical detector generates a beat note at (v&#x2212;Nf)&#x2212;(v+Nf). The beat note and a reference oscillator signal are processed by the circuit to generate a loop-filtered error signal to input to the VCO. Output of the VCO at fdrives the sideband generator and forms the microwave-frequency output signal. The resultant frequency division results in reduced phase noise on the microwave-frequency signal.

Stabilized microwave-frequency source

A highly-coherent chip-based laser generating system includes a disk resonator incorporating a wedge structure fabricated from a silicon dioxide layer of a chip. The disk resonator is operable to generate a highly-coherent laser from a low-coherence optical pump input provided at an optical power level as low as 60 &#x3bc;W. The disk resonator is fabricated with sub-micron cavity size control that allows generation of a highly-coherent laser using a controllable Stimulated Brillouin Scattering process that includes matching of a cavity free-spectral-range to a Brillouin shift frequency in silica. While providing several advantages due to fabrication on a chip, the highly-coherent laser produced by the disk resonator may feature a Schawlow-Townes noise level as low as 0.06 Hz/Hz (measured with the coherent laser at a power level of about 400 &#x3bc;W) and a technical noise that is at least 30 dB lower than the low-coherence optical pump input.

Chip-based laser resonator device for highly coherent laser generation

A frequency comb generator fabricated on a chip with elimination of a disadvantageous reflow process, includes an ultra-high Q disk resonator having a waveguide that is a part of a wedge structure fabricated from a silicon dioxide layer of the chip. The disk resonator allows generation of a frequency comb with a mode spacing as low as 2.6 GHz and up to 220 GHz. A surface-loss-limited behavior of the disk resonator decouples a strong dependence of pumping threshold on repetition rate.

Chip-based frequency comb generator with microwave repetition rate

An optical apparatus comprises a waveguide substrate and an optical reference cavity. The optical reference cavity comprises an optical waveguide formed on the waveguide substrate and arranged to form a closed loop greater than or about equal to 10 cm in length. The RMS resonance frequency fluctuation is less than or about equal to 100 Hz. The Q-factor can be greater than or about equal to 10. The optical waveguide can exhibit optical loss less than or about equal to 0.2 dB/m for propagation of an optical signal along the optical waveguide. The closed loop path can comprise two or more linked spirals greater than or about equal to 1 meter in length and can occupy an area on the waveguide substrate less than or about equal to 5 cm.

On-chip optical reference cavity exhibiting reduced resonance center frequency fluctuations

A method of manufacturing a waveguide eliminates a prior art reflow step and introduces certain new steps that permit fabricating of an ultra-low loss waveguide element on a silicon chip. The ultra-low loss waveguide element may be adapted to fabricate a number of devices, including a wedge resonator and a ultra-low loss optical delay line having an extended waveguide length.

Growing community of inventors

Pasadena, CA, United States of America

Hansuek Lee