Abstract
Researchers at the University of Central Florida have developed a new linear modulator with potentially infinite SFDR and multi-gigahertz bandwidth that offers possible negative insertion loss and very low Vpi, in the range of few milivolts, compared to existing technologies. Current linear modulators offer limited bandwidth and spurious-free dynamic range (SFDR) as electro-optic modulators and power handling as directly modulated lasers--also incurring high insertion loss and high Vpi. While a conventional method for linearizing modulators uses a complicated feedforward electrical circuit to correct for nonlinearities, with still-limited SFDR, the new technology offers pure linear response without the need for a correcting circuit. This linear optical modulator is useful in signal processing, fiber optic communication, frequency comb sources, computer interconnect, radio frequency communication, and radio frequency synthesis.
Technical Details
The UCF linear optical modulator achieves a linear response by phase modulating the output of an injection locked slave laser, or modulating the resonance of an injection locked slave laser, and combining the modulated output with the injection source signal from the master laser. The modulator uses a resonant cavity in one arm of a Mach Zehnder interferometer. The output frequency of the resonant cavity device, the same as the injected signal, collects a phase related to the frequency difference--the resonant cavity frequency and the detuning of the injected cavity frequency--leading to the arcsine of the detuning. Combining the arcsine phase modulated signal with a coherent signal creates a detected signal following the standard interferometer expression.
Benefit
Potentially infinite SFDRMulti-GHz bandwidthNegative insertion lossVery low VpiNo need for a correcting circuitMarket Application
Signal processingFiber optic communicationFrequency comb sourcesComputer interconnectRadio frequency communication and synthesis
Brochure
