We describe measurement results of silicon photonic circuits at cryogenic temperatures. The interplay between optically induced heating and free carrier dynamics in nano-photonic ring resonators is ...investigated at temperatures down to 1.8 K. We find that the life-time of free carriers generated by two-photon absorption in silicon waveguides is reduced from 1.9 ns at room temperature to less than 100 ps below 10K. At the same time the thermal relaxation time is significantly elongated. Our work provides the first cryogenic measurement of ultra-short free-carrier lifetimes in silicon waveguides. The results further indicate that integrated optical chips can be easily thermo-optically stabilized at low temperatures.
We present a novel method to perform universal black-box optimization of pixel-discrete nanophotonic devices based on reinforcement learning. We demonstrate the capabilities of our method for a ...silicon-on-insulator waveguide-mode converter with > 95% conversion efficiency.
The integration of quantum photonics devices in nanophotonic platforms is a promising approach for implementing scalable quantum systems for quantum sensing and communications applications. ...Superconducting nanowire single-photon detectors (SNSPDs) have developed into the most popular photon counting devices due to their high detection efficiency, low dark count rates, and time uncertainty (jitter). As many integrated structures, waveguide-coupled SNSPDs can benefit from the use of subwavelength gratings, which are periodic planar structures that enable the synthesis of metamaterials with tailorable optical properties, namely refractive index, wavelength dispersion, and anisotropy. In this work, we report on our latest advances regarding single-photon detection in silicon nitride waveguides, including the novel use of subwavelength grating metamaterials to enhance the performance of SNSPDs.
Wavelength-sized silicon disk cavities in superfluid helium exhibit blue-shifted bistability near the λ-point when subject to high optical input power. At lower temperature, we observe symmetric ...lineshapes and obtain a large intracavity photon number of 40,000.
We investigate the timing accuracy of SNSPDs under illumination with varying photon numbers and find a reduction of latency time by more than 100 ps as well as sub-3 ps jitter at high photon flux.
We present a hybrid waveguide-fiber optical parametric oscillator (OPO) exploiting degenerate four-wave mixing in tantalum pentoxide. The OPO, pumped with ultrashort pulses at 1.55 \(\mu\)m ...wavelength, generated tunable idler pulses with up to 4.1 pJ energy tunable between 1.63 \(\mu\)m and 1.68 \(\mu\)m center wavelength. An upper bound for the total tolerable cavity loss of 32 dB was found, rendering a chip-integrated OPO feasible as a compact and robust light source.
The complexity of applications addressed with photonic integrated circuits is steadily rising and poses increasingly challenging demands on individual component functionality, performance and ...footprint. Inverse design methods have recently shown great promise to address these demands using fully automated design procedures that enable access to non-intuitive device layouts beyond conventional nanophotonic design concepts. Here we present a dynamic binarization method for the objective-first algorithm that lies at the core of the currently most successful inverse design algorithms. Our results demonstrate significant performance advantages over previous implementations of objective first algorithms, which we show for a fundamental TE00 to TE20 waveguide mode converter both in simulation and in experiments with fabricated devices.
We develop a piezoelectrically actuated, one-dimensional photonic and phononic crystal nanocavity fabricated from aluminum nitride. High-quality piezo-optomechanical nanobeam cavities with optical Q ...o of 1.2 × 10 5 and mechanical Q m over 10,000 are obtained.
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