hQphotonics
Delivering Revolutionary Low-Phase-Noise Photonic Microwave Oscillators

Microwave oscillators are universal components for communications, defense and aerospace, test and measurement, navigation and timing, digital signal processing, and 5G. Conventional microwave oscillators are based on a high-quality-factor voltage-controlled oscillator (VCO), whose phase noise is further stabilized to a radio-frequency (RF) crystal reference via a phase lock loop (PLL). Therefore, the phase noise of such PLL-based microwave oscillators is limited by the multiplication of the crystal reference phase noise. Photonic microwave oscillators based on optical frequency division (OFD) and frequency combs provide a powerful approach to generating microwave signals with phase noise much lower than conventional electronic-based microwave oscillators. However, high-performance photonic microwave oscillators are currently limited to tabletop scale demonstrations with large sizes, weights, and power consumption (SWAP). This perfectly illustrates the need for small-sized high-performance photonic microwave oscillators with lower SWAP and turn-key operation.

hQphotonics is addressing this need with ultra-low phase noise (ULPN) photonic microwave oscillators and synthesizers powered by the electro-optical frequency division (eOFD) technology that displays ultra-high spectral purity to fit various applications. The eOFD technology uses an electro-optical frequency comb to divide the phase noise of ultra-stable optical references to the microwave output. It requires fewer components than tabletop photonic microwave oscillators based on optical frequency division, which requires a cavity-stabilized laser reference, an octave-spanning mode-locked frequency comb, and a highly-linear fast photo detector. This further allows for commercializing compact and automatic-control photonic microwave oscillators with ultra-low phase noise and resistance against environmental vibrations and temperature.

Recently, hQphotonics demonstrated a record low phase noise, 40 GHz oscillator (see figure A), with dimensions of 10x9x2 inches and phase noise of -153 dBc/Hz at 10kHz (40 GHz carrier), which represents over 30 dB phase noise improvement than other top grade commercial 40 GHz microwave oscillators.

hQphotonics was also grouped with other research teams for the GRYPHON program by Defense Advanced Research Projects Agency (DARPA) to develop ten cubic-centimeter light-on-chip high-performance photonic microwave oscillators and synthesizers for next-generation microwave applications.

“Our solution competently resolves obstacles with the achievement of ultra-low phase noise at microwave rate and operation at highly-desirable higher frequencies in the 10-100 GHz range, and generation of broadly tunable photonic microwave synthesizers while maintaining the low phase noise,” says Jiang Li, president of hQphotonics.

Li’s in-depth industry knowledge stems from his experience as a Ph.D. researcher studying newer ways to generate low-noise integrated lasers and low-phase noise photonic microwave oscillators at the California Institute of Technology (Caltech). hQphotonics is a spinoff from the applied physics department at Caltech. Cofounders of hQphotonics include Dr. Jiang Li and Prof. Kerry Vahala from Caltech.

In the digital signal processing space, high-speed analog-to-digital converters (ADC) require low-timing-jitter, high-speed reference clocks to perform digital sampling. hQphotonics reduces the timing-jitter for the ADC high-speed reference clock using its eOFD-based photonic microwave oscillators. Moreover, The hQphotonics eOFD-based photonic microwave oscillators can operate in the highly desirable, higher frequencies from K band to millimeter wave, with ultra-low phase noise and amplitude noise. This enables a much-higher modulation bandwidth, higher spectral efficiency, and lower error rate in wireless coherent communications. hQphotonics also designs ultra-stable photonic microwave oscillators for spectral analysis and phase noise measurements. With the hQphotonics eOFD photonic microwave oscillator, a client in the test and measurement sector improves the sensitivity for spectral analysis and phase noise measurement by orders of magnitude.