Extracting light into free space is one of the challenges to face when dealing with solid-state emitters embedded within high-index materials. In particular, improving the extraction efficiency has been the object of intensive research when intrinsically dim light sources, like single-photon emitters, are implemented for fundamental science and quantum information technology applications.

Here, we show that metallic nano-rings, transferred on a gold-coated substrate, can be implemented to increase the extraction efficiency of single photons emitted by InAs quantum dots, thanks to the focusing effect of the plasmonic device. Furthermore, we show that such a device is scalable and gives broadband (over 60 nm) operation, as opposed to narrowband cavity-based geometries.

Silicon photonics has evolved significantly since the 1980s, transitioning from high-confinement waveguides to a technology integrated with CMOS industry processes, solidifying its dominance in the transceiver market. Despite this success, it remains a technology in active development with vast potential applications, particularly driven by the demand for faster data processing in AI and ML. With conventional computing architectures reaching limits, there's a growing need for faster data transmission, where silicon photonics excels. Beyond data centers and telecommunications, it holds promise in LiDAR, quantum computing, and medical applications, yet challenges like cost and regulation remain. The market is expected to experience rapid growth, reaching over $600M by 2028, showcasing its increasing importance in modern computing, communication, and sensing systems.

This conference presentation was prepared for SPIE Photonics Europe, 2024.

In the last couple of decades huge effort has been put into development of photonics platforms based on various materials such as Si, Si3N4, InP, LiNbO3, GaAs and others. Only few of them (Si, Si3N4, InP) have turned into eco-systems resembling semiconductors industry of design house, foundries, fabless companies and multi project wafer (MPW) services of photonics integrated circuits (PICs). While various photonic platforms have matured to industrial level, they still have numerous challenges including limits set by material properties, expensive fabrication and complicated hybrid integration.

Polymer materials provide numerous advantages over semiconductor and oxide/nitride platforms: combination of passive and active elements, simple fabrication techniques, Integration of other elements for hybrid platform, wide wavelength range and multilayer structure.

We will present the results of developed polymer photonic platform with active and passive elements based on SU-8 and polymethylmethacrylate photoresist.

Hybrid integration of ferroelectric thin films is a one possible route for obtaining high-speed electro-optic modulation on photonic integrated platforms. Excellent electro-optic modulators have been shown using the thin film lithium niobate technology which relies on bonding of transfer printing monocrystalline layers onto existing photonic circuits. The Pockels coefficients of lithium niobate are quite good, but lead zirconate (PZT) and barium titanate (BTO) exhibit coefficients that are several factors higher. PZT and BTO layers with high quality are grown using a cheap and up-scalable method of chemical solution deposition. We present electro-optic characterization of these thin films. Progress in the deposition procedure has led to thin films with an excellent effective Pockels coefficient. We demonstrate integrated electro-optic modulators using both PZT and BTO thin films, in combination with both Si and SiN waveguides, demonstrating the versatility and scalability of thin ferroelectric films grown using a wet chemical process.

Miniaturization through micro-optics and integrated photonics in special applications requires adhesive-free, stable fiber connections in terms of position and power. Our laser welding equipment directly joins fibers to these components.

This conference presentation was prepared for SPIE Photonics Europe, 2024.

GeSn alloys are promising group IV material, compatible with silicon manufacturing, to develop new class of active devices in the 2-4 µm wavelength range. We show the high potential of GeSnOI technology to develop integrated laser sources and detectors for this purpose.

Amplification of ultrafast optical pulses is key to a large number of applications in photonics. While ultrashort pulse amplification is well established in optical gain fibers, it is challenging to achieve in photonic-chip integrated waveguides, due to their inherent high-optical nonlinearity.

Here, we demonstrate for the first-time femtosecond pulse amplification on an integrated photonic chip. Our approach translates the concept of chirped pulse amplification to the chip level. Specifically, we leverage tailored all-normal dispersion, large mode-area gain waveguides to realize a low-nonlinearity, high-gain, short-length optical amplifier in which pulse propagation is dominated by dispersion. We show more than 17dB amplification of ultrashort pulses from a 1 GHz femtosecond source at center wavelength of 1815 nm. The amplified pulses have an on-chip output pulse peak power of 800 W with a pulse duration of 116 fs.

This conference presentation was prepared for SPIE Photonics Europe, 2024.

In this presentation, an overview of the current status and applications of the Al2O3-on-insulator platform will be given.

In this talk, we will discuss the integration of GeSbTeSeS alloys on silicon photonic circuits for applications in non-linear optics and programmable photonics.

We present Ligentec’s scalable silicon nitride photonics platform and highlight our developments towards heterogeneously integrating active materials for detection and modulation on top of this passive platform.

Combining the strength of multiple photonic and electronics concepts in one hybrid and multi-chip platform is a promising solution for the diversification of chips for specific computing tasks to boost performance. Using additive and CMOS compatible one- (OPP) and two-photon polymerization (TPP), i.e. flash-TPP printing, we create low-loss 3D integrated photonic chips for scalable and parallel interconnects, which is challenging to realize in 2D. Here, we demonstrate the CMOS compatibility of such technology by merging polymer-based 3D photonic chips with diverse photonic platforms. We interfaced 3D waveguides on top of semiconductor (GaAs) quantum dot micro-lasers, yielding very high emission collection efficiency into the waveguides at cryogenic temperatures (4 K). Furthermore, we integrated our technology with silicon-on-insulator (SOI) platforms by efficiently coupling light from 2D planar SiN waveguides into out-of-plane 3D waveguides. With this, we lay a promising foundation for scalable integration of hybrid photonic and electronic platforms.

This work presents and discusses the results of developing the first integrated photonic platform for the mid-IR spectral range, MIRPIC (Mid-IR Photonic Integrated Circuits). The platform is based on the heterogeneous integration of mid-IR light sources (QCLs), Ge-on-Si waveguiding components, and mid-IR photon detectors. We will present the platform's general concept along with the library of individual components developed and tested so far, discussing them in the context of operational parameters. Recent results will be showcased, documenting progress in MIRPIC platform development while pointing out the main challenges faced by the technology.

This work has received support from the National Centre for Research and Development through project MIRPIC (TECHMATSTRATEG-III/0026/2019-00).

Improving current approaches to shaping ultraviolet light beams will spark new applications in healthcare and quantum information. We will discuss recent advances in controlling UV light with CMOS photonic chips.

This conference presentation was prepared for SPIE Photonics Europe, 2024.

In recent years, integrated optical phased array (iOPA) devices have gained significant attention due to their remarkable precision in shaping light beam, essential for various applications such as free space optical communication, lidar, AR/VR, and biomedical imaging. However, a notable technological gap remains for visible light applications, as silicon (Si)-technology is only transparent above 1.1 μm, does not support visible spectrum. This study addresses this challenge by introducing a platform that is suitable for visible spectrum. Our technology operates with the wideband visible spectrum (405-660 nm) through the monolithic integration of silicon nitride (Si3N4) waveguide membrane and thin-film Lead-Zirconate Titanate (PZT) based PiezoMEMS. This technology will lay the groundwork for future advancements in areas that require precise light beam shaping at the visible spectrum, including microscopy, sensing, diagnosis, and manufacturing.

This conference presentation was prepared for SPIE Photonics Europe, 2024.

This conference presentation was prepared for SPIE Photonics Europe, 2024.

This conference presentation was prepared for SPIE Photonics Europe 2024.

Neuromorphic computing based on integrated photonic circuits on-chip is a burgeoning area aiming to achieve high-speed, energy-efficient, and low-latency data processing to alleviate artificial intelligence-related applications, such as autonomous driving and speech recognition. Outstanding properties of phase change materials, such as reversible and fast switching of the states and high index contrast together with a wide spectral region integrated in nanophotonic devices provide a unique on-chip hybrid system to obtain fast modulators, switches and to realize neuromorphic systems on-chip.

We designed on-chip reconfigurable broadband nanocrystalline graphene-assisted waveguide switch and memory unit covering the whole telecommunication C-band based on absorption modulation of integrated Ge2Sb2Te5 (GST) PCM cells. GST state switching is triggered via patterned nanocrystalline graphene external microheaters placed on top of silicon nitride waveguide and beneath PCM cell.

In Intensity Modulation/Direct Detection protocols, chromatic dispersion is a major impairment source, inducing intersymbol interference which leads to BER degradation at the receiver. Fiber Bragg gratings and Dispersion Compensating fibers are nowadays used for equalization, despite the former showing limited performance in compensating all Wavelength Division Multiplexing aggregate channels simultaneously, and the latter being non-tunable devices that introduce latency. In former works, we demonstrated channel equalization via an all-optical delayed complex perceptron, which is implemented as an integrated feed-forward photonic neural network trained for PAM2, PAM4, and PAM8 signals up to 125 km. The network performs an all-optical signal processing with minimized latency, reconfigurability, and low power consumption. This design is now applied for the equalization of complex modulation formats encoded in Orthogonal Frequency Division Multiplexed signals. This allows for an increase in spectral efficiency and enforces the adaptability of the network to different modulation formats.

In integrated photonics, precise control of light signals plays a pivotal role. Typically, light routing within photonic devices relies on multi-mode interferometers and micro resonators. Here, we investigate, both theoretically and experimentally, the use of such devices in achieving a versatile 3x3 tunable switch where light can be routed from each input port to any output ports. To accomplish this, we have designed and tested various 3x3 coupler structures in silicon. The results from the analysis of these structures, using coupled mode theory and a transfer matrix, are in good agreement with the experimental findings. We show that the device can cross the signal from the external waveguide while maintaining the central waveguide unaltered, or even achieving a balanced output across all three output ports. Direct (1-1), split (1-2+3), and cross (1-3) paths, along with any arbitrary combination thereof. In quantum optics, a single 3x3 coupler allows the manipulation of the photon state vector within almost the whole three-dimensional Bloch sphere.

Group IV materials suffers from a lack of efficient light generation for the on-chip integration of active photonic component on silicon (Si). One of the solutions is to use new material like Germanium-tin alloys (GeSn) that can provide direct band gap alignment of the band structure. The use quantum well (QW) is known, in principle, to favor room temperature laser operation at reasonable thresholds over bulk material. While most of advances were performed with bulk materials, exploring adequate designs of GeSn/SiGeSn based QW including strain engineering should be helpful for futures developments of Si-based active photonic devices.

Here we demonstrate up to 290 K laser operation in GeSn/GeSn multi-QW microdisks cavities under optical pumping. The QW and barrier were performed by varying the Sn content. We used specific layer transfer technology and a Silicon Nitride (SiN) stressor layer was introduced to inject tensile strain in the active region such to enhance the directness of the transition. Interestingly this is the highest temperature of operation for GeSn quantum wells lasers. This progress opens the route towards room temperature electrically pumped laser operating.

Programmable photonic circuits manipulate the flow of light on a chip by electrically controlling a set of tunable analog gates connected by optical waveguides. Light is distributed and spatially rerouted to implement various linear functions by interfering signals along different paths. A general-purpose photonic processor can be built by integrating this flexible hardware in a technology stack comprising an electronic monitoring and controlling layer and a software layer for resource control and programming. This processor can leverage the unique properties of photonics in terms of ultra-high bandwidth, high-speed operation, and low power consumption while operating in a complementary and synergistic way with electronic processors. This talk will review the recent advances in the field and it will also delve into the potential application fields for this technology including, communications, 6G systems, interconnections, switching for data centers and computing.