Peter T. S. DeVore

Stimulated supercontinuum generation extends broadening limits in silicon

We demonstrate that stimulated supercontinuum generation alleviates restrictions on spectral broadening in silicon waveguides. At telecommunications wavelengths, two-photon and free-carrier absorption typically deplete the pump before large broadening factors can be achieved. However, broadening via modulation instability (MI) can be enhanced by seeding, which also substantially improves the energy efficiency of spectral broadening in media with nonlinear loss. Coherent seeding also generates a stable output spectrum, in contrast to conventional approaches where broadening starts from noise. The combination of self-phase modulation and stimulated modulation instability generates broadening factors in excess of 40-fold at moderate intensity levels, with >15-times better energy efficiency.

Coherent Time-Stretch Transform for Near-Field Spectroscopy

The coherent time-stretch transform enables high-throughput acquisition of complex optical fields in single-shot measurements. Full-field spectra are recovered via temporal interferometry on waveforms dispersed in the temporal near field. Real-time absorption spectra, including both amplitude and phase information, are acquired at 37 MHz.

Rogue events and noise shaping in nonlinear silicon photonics

We revisit recent work on the generation of extreme optical events via nonlinear dynamics in silicon waveguides. The underlying processes, modulation instability and stimulated Raman scattering, are able to reshape normally distributed initial conditions into skewed output statistics whose properties can be tailored by controlling experimental variables. While these are both gain processes, they bear fundamental differences: modulation instability is a broadband parametric process, whereas stimulated Raman scattering is a narrowband inelastic process. As a result, they respond to different forms of input noise. Specifically, the extreme events generated spontaneously by modulation instability evidence a strong sensitivity to a particular input noise component. This sensitivity can be controllably seeded to generate coherent supercontinuum radiation, which also offers a means to alleviate conventional free-carrier limitations to chip-scale spectral broadening.

Impact of Optical Nonlinearity on Performance of Photonic Time-Stretch Analog-to-Digital Converter

Wideband real-time analog-to-digital converters are the central tools in waveform analyzers, communication systems, and radar technology. Photonic time-stretch analog-to-digital converters (TSADCs) utilize a broadband optical source and an optical link to extend the capabilities of real-time digitizers, allowing acquisition of wideband radio frequency (RF) signals with high resolution. In the TSADC, it is desirable to improve the signal-to-noise-and-distortion ratio and effective number of bits by increasing the optical power. Here, we numerically evaluate the impact of optical nonlinearity on TSADC performance. It is demonstrated that the optical nonlinearity can impose an upper limit on the effective number of bits and that the RF bandwidth limitation due to dispersion penalty depends on optical power. The trends presented here can also be applied to other optical links in which optical nonlinearity and dispersion are significant.

Analog optical computing primitives in silicon photonics

Optical computing accelerators help alleviate bandwidth and power consumption bottlenecks in electronics. We show an approach to implementing logarithmic-type analog co-processors in silicon photonics and use it to perform the exponentiation operation and the recovery of a signal in the presence of multiplicative distortion. The function is realized by exploiting nonlinear-absorption-enhanced Raman amplification saturation in a silicon waveguide.

Demonstration of Vpi Reduction in Electrooptic Modulators Using Modulation Instability

We show a 10 fold reduction in an electro optic modulators half-wave voltage by employing modulation instability. Experimental results are reported up to 50 GHz.

Energy-efficient coherent supercontinuum generation in silicon

Stimulated supercontinuum generation via coherent seeding is numerically demonstrated to produce continua of broader bandwidth and higher coherence than the conventional unseeded case. Implications for energy efficient generation of WDM channels are discussed.

Silicon photonics cloud (SiCloud)

Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.

Stimulated Modulation Instability in Silicon for Energy Efficient Supercontinuum Generation

Nonlinear losses limit supercontinuum efficiency in silicon. This fundamental limitation can be relaxed and higher energy efficiency and a more stable output can be obtained by stimulating modulation instability with an off-resonant weak seed.

SiCloud: an online education tool for silicon photonics

The silicon photonics industry is projected to be a multibillion dollar industry driven by the growth of data centers. In this work, we present an interactive online tool for silicon photonics. Silicon Photonics Cloud (SiCCloud.org) is an easy to use instructional tool for optical properties of silicon and related materials, waveguide design and modal simulations as well as information capacity of silicon channels.