Integrated photonics

Integrated photonics is the science of manipulating light at the nanoscale. In addition to bringing efficiency, precision, and robustness which is unachievable with large scale conventional optical systems, it is a key technology for optical communications, optical sensors and future quantum technologies.

Image: Schematic of a photonics ADC

Here, we are interested in linear and nonlinear silicon-photonics [1] including the full integration of ultra-stable high power lasers operating in the continuous wave and mode-locked pulsed regime in the near and the mid-Infrared wavelengths range. These systems can be directly implemented into technologies such as integrated optical frequency metrology [2], optical atomic clocks, and photonic analog to digital converters. We work closely with the Solid state lasers team.

Currently, conventional analog to digital converter’s (ADC’s) are major bottlenecks in the advancement of signal processing systems. One of the major obstacles to progress in ADC’s is timing jitter of the sampling pulses, i.e. aperture jitter, which today is on the order of 100 fs, limiting the bandwidth-resolution product of today’s electronic ADCs to about 10 effective number of bits at 1 Gbaud sampling rate. Ultrashort pulse lasers are a promising source for extremely low timing jitter (sub-fs) samplers.

We have shown with bench-top photonically assisted ADCs operating at 41 GHz analog frequency with a record low record low aperture jitter of 15 fs [3] . Our team is working towards miniaturization of such a system, where the integration of an ultralow noise, high power mode-locked laser on chip is the biggest challenge.

Relevant references:
[1] N.Singh, et. al. “Octave-spanning coherent supercontinuum generation in silicon on insu-lator from 1.06 μm to beyond 2.4 μm” Light: Sci. & appl. 7(1), 2018.
[2] N.Singh,et. al. “Silicon photonics optical frequency synthesizer – SPOFS”, Laser and Photonics, 2020.
[3] A.Khilo et. al. “Photonics ADC: Overcoming the bottleneck of electronic jitter”, Opt. Exp. 20, 2012.