Two platform technologies form the basis of OEwaves’ products: the optical Whispering Gallery Mode (WGM) micro-resonator and the Opto-Electronic Oscillator (OEO).
The crystalline optical WGM micro-resonator technology pioneered at OEwaves combines optically transparent crystalline material with unique polishing techniques. WGM resonators are extremely high quality factor (Q), axially symmetric dielectric structures ranging in size from tens of microns to a few mm. They trap light for long periods of time and, so, they have unique linear and nonlinear properties useful for many applications. For example, resonators made with electro-optic crystals, such as lithium niobate, lead to extremely narrow band (1 MHz) optical domain microwave and mm-wave filters, tunable over 40 GHz, centered at any frequency in the microwave or mm-wave range of interest. These resonators can also be used as ultra-high efficiency optical modulators, as well as critical elements in more complex microwave oscillators and photonic receiver front ends for special applications in communications and radar. Resonators made with highly transparent material such as calcium fluoride and magnesium fluoride can be pumped with a few mW of continuous wave light from a laser to produce a comb of optical frequencies. The optical comb can beat on a fast photodiode to produce a highly spectrally pure microwave, mm-wave, or THz signal. The combination of high Q WGM resonators together with semiconductor lasers result in extremely narrow linewidth, highly stable lasers in small form factors. These lasers exhibit narrow linewidth smaller than 200 Hz and display frequency stability better than 10-9 at 1 s. They can be produced at any wavelength for which a semiconductor laser diode is available.
Opto-Electronic Oscillator (OEO)
OEwaves’ patented opto-electronic oscillator (OEO) is based on an approach that is fundamentally distinct from conventional electronic oscillators. These innovative oscillators produce highly spectrally pure microwave and mm-wave signals using an opto-electronic feedback loop. The versatile scheme allows utilization of optical components for low loss and small size in place of conventional, more lossy and bulky microwave and mm-wave components. OEO’s are also inherently less sensitive to vibration and acceleration, and provide the same low spectral purity at all microwave, mm-wave, and higher frequencies. OEwaves has demonstrated a highly advanced OEO that produces ultra-low phase noise of -163 dBc/Hz at 10 kHz offset for a 10 GHz carrier, a performance unmatched by any other oscillator. Variations of our OEO architecture achieving near -145 dBc/Hz at 10 kHz offset are available in compact VME-sized packages (compact OEO) with fixed or tunable frequency within X-Band (tunable OEO). A chip-scale version of our OEO with an architecture based on the use of tiny optical whispering gallery mode micro-resonators produces unmatched spectral purity at X, Ku, Ka, and W-band. Known as the micro-OEO, this OEO comes in a package the size of a dime (US 10 cent coin). Additionally, OEwaves has demonstrated tunable OEOs based on the microresonator technology, capable of producing 20 GHz of tunable frequency centered at Ku, Ka, or W-bands.
Phase Noise Test Measurement
Accompanying the ultra-high performance of our OEO’s, we have productized a fast and fully automated phase noise test system called the PHENOM. This system utilizes microwave photonics techniques to measure phase noise and amplitude noise of an oscillator without the need for a high performance reference oscillator or down-converter. Based on homodyne technique with cross-correlation capability, the PHENOM system measures the phase noise of an oscillator at any operating frequency in the 1 to 60 GHz range rapidly and accurately. The system is also capable of measuring the noise of amplifiers with bandwidth at the same frequency interval.
Ultra Narrow Linewidth Laser Source
OEwaves developed an Ultra-Narrow Linewidth Laser Source based on the self-injection locking of a semiconductor laser diode to our proprietary high quality factor (Q) Whispering Gallery Mode (WGM) optical micro-resonator to achieve robust super-narrow instantaneous spectral linewidth of less than 1 Hz.
With the availability of a super narrow linewidth (or long coherence length) laser source resistant to harsh environments at a low cost and in a small form factor, System Providers for coherent Doppler LIDAR, smart structures sensors, and spectroscopic sensors will greatly improve their system’s measurement range and precision while operating under stringent conditions. This is true for trace gas detectors and monitors, interferometric fiber optic sensor systems, and similar applications as well. Such a laser source allows longer interferometer path length difference and lower phase/frequency noise to enable sensitive detection of minute changes in distance, pressure or acceleration, even under severe environments and without sacrificing system size and cost. These systems service various industries such as conventional and green energy, infrastructure and smart structures, security and defense, and spectroscopy and metrology, etc. In addition, with the capability to offer such performance and features in other wavelengths beyond near-infrared, academic researches, and bio-chemical and medical sensing applications will also benefit from this technology.