arXiv subjects

Gunther Roelkens

Publications and source records attributed to Gunther Roelkens.

16 recordsLinked to original sources

arXiv2026

Micro-Transfer Printing of Lithium Niobate on 200 mm Silicon Photonics: A High-Speed Heterogeneous Wafer-Scale Platform

The rapid growth of artificial intelligence (AI) and other data center applications is driving the demand for photonic interconnects that combine high-speed with low energy consumption, making scalability a critical requirement. Micro-transfer printing (MTP) has emerged as a promising technique for the wafer-scale heterogeneous integration of thin film lithium niobate (TFLN) onto silicon photonics (SiPho) platforms. Here, we demonstrate heterogeneous SiPho TFLN integration across four full 200 mm wafers with a 3sigma placement accuracy down to 420 nm and a printing yield of larger than 95percentage. Low insertion loss less than 2 dB over 600 phase modulators (300 amplitude modulators) is achieved. A half wave voltage of 4 V in push pull configuration, and high-speed modulation with a bandwith larger than 70 GHz is demonstrated on a subset of tested devices.

physics.optics↗

arXiv2025

A 3D-integrated BiCMOS-silicon photonics high-speed receiver realized using micro-transfer printing

Meeting the escalating demands of data transmission and computing, driven by artificial intelligence (AI), requires not only faster optical transceivers but also advanced integration technologies that can seamlessly combine photonic and electronic components. Traditional approaches struggle to overcome the parasitic limitations arising from fabricating those components using different processes. Here, we report a novel 3D heterogeneously integrated optical receiver based on micro-transfer printing (μTP), enabling the co-integration of a compact bipolar CMOS (BiCMOS) electronic chiplet (0.06 mm2) directly onto a silicon photonic integrated circuit (SiPIC). While previous μTP demonstrations have focused primarily on photonic integration, our work pioneers the direct integration of electronics and photonics, significantly enhancing performance and scalability. The resulting optical receiver achieves 224 Gb/s four-level pulse amplitude modulation (PAM-4) operation, delivering -5.2 dBm optical modulation amplitude(OMA) sensitivity at a bit-error rate (BER) of 2.4 x 10-4, a record-small footprint, and an excellent power efficiency of 0.51 pJ/b. This demonstration not only showcases the potential of μTP for high-density, cost-efficient integration but also represents a critical step toward next-generation optical interconnects in the AI era.

physics.optics↗

arXiv2025

Integrated emitters with CMOS-compatible tuning for large scale quantum SiN photonic circuits

Next-generation scalable quantum photonic technologies operating at the single photon level rely on bringing together optimized quantum building blocks with minimal optical coupling losses. Achieving this necessitates the heterogeneous integration of different elements onto a single interposer chip. Integrated quantum emitters are key enablers for generating single photons, inducing quantum nonlinearities, and producing entanglement. In this work, we demonstrate the scalable integration of mature InGaAs quantum dots embedded in GaAs waveguides onto a low-loss SiN photonic platform, as evidenced by a high processing yield of 94.7% using a commercially available micro-transfer printing tool. These integrated emitters are embedded within a p-i-n heterostructure that allows for noise suppression, near-blinking-free operation and wavelength tunability upon CMOS-level electrical biasing. With this, we pave the way for scalable integration of diverse quantum photonic devices on a single chip.

physics.optics↗

arXiv2024

Integrated resonant electro-optic comb enabled by platform-agnostic laser integration

The field of integrated photonics has significantly impacted numerous fields including communication, sensing, and quantum physics owing to the efficiency, speed, and compactness of its devices. However, the reliance on off-chip bulk lasers compromises the compact nature of these systems. While silicon photonics and III-V platforms have established integrated laser technologies, emerging demands for ultra-low optical loss, wider bandgaps, and optical nonlinearities necessitate other platforms. Developing integrated lasers on less mature platforms is arduous and costly due to limited throughput or unconventional process requirements. In response, we propose a novel platform-agnostic laser integration technique utilizing a singular design and process flow, applicable without modification to a diverse range of platforms. Leveraging a two-step micro-transfer printing method, we achieve nearly identical laser performance across platforms with refractive indices between 1.7 and 2.5. Experimental validation demonstrates strikingly similar laser characteristics between devices processed on lithium niobate and silicon nitride platforms. Furthermore, we showcase the integration of a laser with a resonant electro-optic comb generator on the thin-film lithium niobate platform, producing over 80 comb lines spanning 12 nm. This versatile technique transcends platform-specific limitations, facilitating applications like microwave photonics, handheld spectrometers, and cost-effective Lidar systems, across multiple platforms.

physics.optics↗

arXiv2023

Micro-transfer-printed Thin film lithium niobate (TFLN)-on-Silicon Ring Modulator

Thin-film lithium niobate (TFLN) has a proven record of building high-performance electro-optical (EO) modulators. However, its CMOS incompatibility and the need for non-standard etching have consistently posed challenges in terms of scalability, standardization, and the complexity of integration. Heterogeneous integration comes to solve this key challenge. Micro-transfer printing of thin-film lithium niobate brings TFLN to well-established silicon ecosystem by easy "pick and place", which showcases immense potential in constructing high-density, cost-effective, highly versatile heterogeneous integrated circuits. Here, we demonstrated for the first time a micro-transfer-printed thin film lithium niobate (TFLN)-on-silicon ring modulator, which is an important step towards dense integration of performant lithium niobate modulators with compact and scalable silicon circuity. The presented device exhibits an insertion loss of -1.5dB, extinction ratio of -37dB, electro-optical bandwidth of 16GHz and modulation rates up to 45Gps.

physics.optics↗

arXiv2023

Single-Chip Silicon Photonic Processor for Analog Optical and Microwave Signals

The explosion of data volume in communications, AI training, and cloud computing requires efficient data handling, which is typically stored as digital electrical information and transmitted as wireless radio frequency (RF) signals or light waves in optical fibres. Today's communications systems mostly treat the RF and optical signals separately, which results in unnecessary conversion losses and increased cost. In this work, we report the first fully on-chip signal processor for high-speed RF and optical signals based on a silicon photonic circuit. Our chip is capable of both generation and detection of analog electrical and optical signals, and can program a user-defined filter response in both domains. The single silicon photonic chip integrates all essential components like modulators, optical filters, and photodetectors, as well as tunable lasers enabled by transfer-printed Indium Phosphide (InP) optical amplifiers. The system's configuration is locally programmed through thermo-optic phase shifters and monitored by photodetectors. We demonstrate our chip's capabilities with different combinations of RF and optical signal processing functions, including optical and RF signal generation and filtering. This represents a key step towards compact microwave photonic systems for future wireless communication and sensing applications.

physics.optics↗

arXiv2020

An on-chip III-V-semiconductor-on-silicon laser frequency comb for gas-phase molecular spectroscopy in real-time

Frequency combs, spectra of evenly-spaced narrow phase-coherent laser lines, have revolutionized precision measurements. On-chip frequency comb generators hold much promise for fully-integrated instruments of time and frequency metrology. While outstanding developments are being reported with Kerr, quantum cascade and microring electro-optic combs, the field of high-resolution multiplexed gas-phase spectroscopy has remained inaccessible to such devices, because of their large line spacing, their small number of usable comb lines, the intensity variations between their comb lines, and their limited photonic integrability. Here we identify a path to broadband gas-phase spectroscopy on a chip. We design a low-noise III-V-on-silicon comb generator on a photonic chip, that emits a flat-top spectrum of 1400 lines at a repetition frequency of 1.0 GHz, a feature never approached by other ultra-miniaturized comb synthesizers. With dual-comb spectroscopy, our near-infrared electrically-pumped laser records high-resolution (1 GHz) sensitive multiplexed spectra with resolved comb lines, in times as short as 5 microseconds. Isotope-resolved 12C/13C detection in carbon monoxide is performed within 1 millisecond. With further developments, entire high-resolution spectroscopy laboratories-on-a-chip may be manufactured at the wafer scale. In environmental sensing, broad networks of spectrometers could be densely field-deployed to simultaneously monitor, in real time, sources and sinks of greenhouse gases, industrial pollution or noxious emissions of motor vehicles.

physics.optics↗

arXiv2020

Second Harmonic Generation Enabled by Longitudinal Electric Field Components in Photonic Wire Waveguides

We investigate type I second harmonic generation in III-V semiconductor wire waveguides aligned with a crystallographic axis. In this direction, because of the single nonzero tensor element of III-V semiconductors, only frequency conversion by mixing with the longitudinal components of the optical fields is allowed. We experimentally study the impact of the propagation direction on the conversion efficiency and confirm the role played by the longitudinal components through the excitation of an antisymmetric second harmonic higher order mode.

physics.optics↗

arXiv2018

Silicon Waveguides for High-Speed Optical Transmissions and Parametric Conversion around 2 $μ$m

We show that single mode Si waveguides efficiently sustain high-speed transmissions at 2 $μ$m. We report the transmission of a 10 Gbit/s signal over 7 cm with a power penalty below 1 dB. Parametric conversion in the continuous wave regime is also demonstrated using the same waveguide structure with a conversion window over 70 nm and an efficiency as high as-25 dB that can be further increased in the pulsed pump regime.

physics.optics↗

arXiv2018

Physical origin of higher-order soliton fission in nanophotonic semiconductor waveguides

Supercontinuum generation in Kerr media has become a staple of nonlinear optics. It has been celebrated for advancing the understanding of soliton propagation as well as its many applications in a broad range of fields. Coherent spectral broadening of laser light is now commonly performed in laboratories and used in commercial white light sources. The prospect of miniaturizing the technology is currently driving experiments in different integrated platforms such as semiconductor on insulator waveguides. Central to the spectral broadening is the concept of higher-order soliton fission. While widely accepted in silica fibers, the dynamics of soliton decay in semiconductor waveguides is yet poorly understood. In particular, the role of nonlinear loss and free carriers, absent in silica, remains an open question. Here, through experiments and simulations, we show that nonlinear loss is the dominant perturbations in wire waveguides, while free-carrier dispersion is dominant in photonic crystal waveguides.

physics.optics↗

arXiv2015

On-chip optical event horizon

The interaction of waves in nonlinear Kerr waveguides are, under some circumstances, similar to the physics occurring at the horizon of black and white holes. Here, we investigate this analogy in an integrated nonlinear photonic structure through the reflection of a continuous wave on an intense pulse. The resulting frequency conversion of the continuous wave is experimentally demonstrated in a silicon photonic wire waveguide and confirmed by simulations using the generalized nonlinear Schrödinger equation. This demonstration paves the way to efficient all-optical signal processing functionality integrated on a CMOS-compatible waveguide platform.

physics.optics↗

arXiv2014

Coherent supercontinuum generation in a silicon photonic wire in the telecommunication wavelength range

We demonstrate a fully coherent supercontinuum spectrum spanning 500 nm from a silicon-on-insulator photonic wire waveguide pumped at 1575 nm wavelength. An excellent agreement with numerical simulations is reported. The simulations also show that a high level of two-photon absorption can essentially enforce the coherence of the spectral broadening process irrespective of the pump pulse duration.

physics.optics↗

arXiv2014

An octave spanning mid-infrared frequency comb generated in a silicon nanophotonic wire waveguide

We demonstrate an octave-spanning frequency comb with a spectrum covering wavelengths from 1,540 nm up to 3,200 nm. The supercontinuum is generated by pumping a 1-cm long dispersion engineered silicon wire waveguide by 70 fs pulses with an energy of merely 15 pJ. We confirm the phase coherence of the output spectrum by beating the supercontinuum with narrow bandwidth CW lasers. We show that the experimental results are in agreement with numerical simulations.

physics.optics↗

arXiv2014

Dispersive wave emission and supercontinuum generation in a silicon wire waveguide pumped around the 1550 nm telecommunication wavelength

We experimentally and numerically study dispersive wave emission, soliton fission and supercontinuum generation in a silicon wire at telecommunication wavelengths. Through dispersion engineering, we experimentally confirm a previously reported numerical study [1] and show that the emission of resonant radiation from the solitons can lead to the generation of a supercontinuum spanning over 500 nm. An excellent agreement with numerical simulations is observed.

physics.optics↗

arXiv2012

Bridging the Mid-Infrared-to-Telecom Gap with Silicon Nanophotonic Spectral Translation

Expanding far beyond traditional applications in optical interconnects at telecommunications wavelengths, the silicon nanophotonic integrated circuit platform has recently proven its merits for working with mid-infrared (mid-IR) optical signals in the 2-8 μm range. Mid-IR integrated optical systems are capable of addressing applications including industrial process and environmental monitoring, threat detection, medical diagnostics, and free-space communication. Rapid progress has led to the demonstration of various silicon components designed for the on-chip processing of mid-IR signals, including waveguides, vertical grating couplers, microcavities, and electrooptic modulators. Even so, a notable obstacle to the continued advancement of chip-scale systems is imposed by the narrow-bandgap semiconductors, such as InSb and HgCdTe, traditionally used to convert mid-IR photons to electrical currents. The cryogenic or multi-stage thermo-electric cooling required to suppress dark current noise, exponentially dependent upon the ratio Eg/kT, can limit the development of small, low-power, and low-cost integrated optical systems for the mid-IR. However, if the mid-IR optical signal could be spectrally translated to shorter wavelengths, for example within the near-infrared telecom band, photodetectors using wider bandgap semiconductors such as InGaAs or Ge could be used to eliminate prohibitive cooling requirements. Moreover, telecom band detectors typically perform with higher detectivity and faster response times when compared with their mid-IR counterparts. Here we address these challenges with a silicon-integrated approach to spectral translation, by employing efficient four-wave mixing (FWM) and large optical parametric gain in silicon nanophotonic wires.

physics.optics↗

arXiv2011

On-chip parametric amplification with 26.5~dB gain at telecommunication wavelengths using CMOS-compatible hydrogenated amorphous silicon waveguides

We present the first study of parametric amplification in hydrogenated amorphous silicon waveguides. Broadband on/off amplification up to 26.5~dB at telecom wavelength is reported. Measured nonlinear parameter is 770~$\textrm{W}^{-1} \textrm{m}^{-1}$, nonlinear absorption 28~$\textrm{W}^{-1} \textrm{m}^{-1}$, bandgap $1.61$~eV.

physics.optics↗