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Chris G. H. Roeloffzen

Publications and source records attributed to Chris G. H. Roeloffzen.

6 recordsLinked to original sources
arXiv2020

High-purity microwave generation using a dual-frequency hybrid integrated semiconductor-dielectric waveguide laser

We present an integrated semiconductor-dielectric hybrid dual-frequency laser operating in the 1.5 $μ$m wavelength range for microwave and terahertz (THz) generation. Generating a microwave beat frequency near 11 GHz, we observe a record-narrow intrinsic linewidth as low as about 2 kHz. This is realized by hybrid integration of a single diode amplifier based on indium phosphide (InP) with a long, low-loss silicon nitride (Si$_3$N$_4$) feedback circuit to extend the cavity photon lifetime, resulting in a cavity optical roundtrip length of about 30 cm on a chip. Simultaneous lasing at two frequencies is enabled by introducing an external control parameter for balancing the feedback from two tunable, frequency-selective Vernier mirrors on the Si$_3$N$_4$ chip. Each frequency can be tuned with a wavelength coverage of about 80 nm, potentially allowing for the generation of a broad range of frequencies in the microwave range up to the THz range.

physics.app-ph↗
arXiv2020

Ultra-narrow linewidth hybrid integrated semiconductor laser

We demonstrate a hybrid integrated and widely tunable diode laser with an intrinsic linewidth as narrow as 40 Hz, achieved with a single roundtrip through a low-loss feedback circuit that extends the cavity length to 0.5 meter on a chip. Employing solely dielectrics for single-roundtrip, single-mode resolved feedback filtering enables linewidth narrowing with increasing laser power, without limitations through nonlinear loss. We achieve single-frequency oscillation with up to 23 mW fiber coupled output power, 70-nm wide spectral coverage in the 1.55 $μ$m wavelength range with 3 mW output, and obtain more than 60 dB side mode suppression. Such properties and options for further linewidth narrowing render the approach of high interest for direct integration in photonic circuits serving microwave photonics, coherent communications, sensing and metrology with highest resolution.

physics.optics↗
arXiv2019

Hybrid integrated semiconductor lasers with silicon nitride feedback circuits

Hybrid integrated semiconductor laser sources offering extremely narrow spectral linewidth as well as compatibility for embedding into integrated photonic circuits are of high importance for a wide range of applications. We present an overview on our recently developed hybrid-integrated diode lasers with feedback from low-loss silicon nitride (Si3N4 in SiO2) circuits, to provide sub-100-Hz-level intrinsic linewidths, up to 120 nm spectral coverage around 1.55 um wavelength, and an output power above 100 mW. We show dual-wavelength operation, dual-gain operation, laser frequency comb generation, and present work towards realizing a visible-light hybrid integrated diode laser.

physics.optics↗
arXiv2019

8x8 Reconfigurable quantum photonic processor based on silicon nitride waveguides

The development of large-scale optical quantum information processing circuits ground on the stability and reconfigurability enabled by integrated photonics. We demonstrate a reconfigurable 8x8 integrated linear optical network based on silicon nitride waveguides for quantum information processing. Our processor implements a novel optical architecture enabling any arbitrary linear transformation and constitutes the largest programmable circuit reported so far on this platform. We validate a variety of photonic quantum information processing primitives, in the form of Hong-Ou-Mandel interference, bosonic coalescence/anticoalescence and high-dimensional single-photon quantum gates. We achieve fidelities that clearly demonstrate the promising future for large-scale photonic quantum information processing using low-loss silicon nitride.

quant-ph↗
arXiv2015

Full-C-band, sub-GHz-resolution Nyquist-filtering (de)interleaver in photonic integrated circuit

Nyquist wavelength division (de)multiplexing (N-WDM) is a highly promising technique for next-generation high-speed elastic networks. In N-WDM, Nyquist filtering is an essential function that governs the channel spectral efficiency. However, most Nyquist filter implementations to date require either expensive, power-hungry digital electronics or complex arrangements of bulky optical components, hindering their adoption for important functions such as Nyquist channel shaping and reconfigurable optical add-drop multiplexers (ROADMs) for Nyquist super-channels. Here, we present a distinctive solution with low-cost, power-efficient, and simple-device natures, which is an on-chip optical Nyquist-filtering (de)interleaver featuring sub-GHz resolution and a near-rectangular passband with 8% transition band. This unprecedented performance is provided by a simple photonic integrated circuit comprising a two-ring-resonator-assisted Mach-Zehnder interferometer, which features high circuit compactness using high-index-contrast Si3N4 waveguide, while showing sub-picosecond optical delay accuracy enabling full C-band coverage with more than 160 effective free spectral ranges of 25 GHz across a bandwidth over 4 THz. Such devices show clear potential for chip-scale realization of N-WDM transceivers and ROADMs.

physics.optics↗