Search

We demonstrate a flow cytometer in which structured light illumination is used to attribute fluorescent and scattering signals to their excitation wavelength. A suitable multi-color light source emitting structured illumination patterns at 405, 488, 561 and 640 nm is developed based on a silicon nitride photonic integrated circuit and cytometry experiments are conducted with calibration beads. Performance metrics of the novel cytometer are compared with those of a mature, commercial device. While the experimental device still features a slightly higher sensitivity floor than the commercial one, all but the most weakly stained beads can be categorized. These promising results validate the feasibility of the proposed concept.

Generating visible light with wide tunability and high coherence based on photonic integrated circuits is of high interest for applications in biophotonics, precision metrology and quantum technology. Here we present the first demonstration of a hybrid-integrated diode laser in the visible spectral range. Using an AlGaInP optical amplifier coupled to a low-loss Si3N4 feedback circuit based on microring resonators, we obtain a spectral coverage of 10.8 nm around 684.4 nm wavelength with up to 4.8 mW output power. The measured intrinsic linewidth is 2.3$\pm$0.2 kHz., Comment: 8 pages, 6 figures

A hybrid integrated InP-Si3N4 dual tunable laser module is deployed as a highly flexible source for converged optical/mm-wave fronthaul. Experimental results show the wavelength flexible delivery of 5G signals over analog radio-over-fiber, incorporating wireless transmission at 60 GHz, with received EVMs as low as 5%.

In this article, we provide a review of fabrication platforms and state of the art developments in the area of silicon nitride photonic integrated circuits (PICs) for the visible wavelength range, mostly employed in bio-medical and chemical sensing applications. Additionally, we introduce PIX4life, the European pilot line for silicon nitride PICs for visible applications. PIX4life provides a unified framework for the development of such PICs, including design and software, fabrication, characterization and packaging.

This paper describes the detailed characterization of a novel InP-Si

Despite chemotherapy, residual tumors often rely on so-called drug tolerant persister (DTP) cells, which evade treatment to give rise to therapy-resistant relapse and refractory disease. Detection of residual tumor cells proves to be challenging because of the rarity and heterogeneity of DTP cells. In the framework of a H2020 project, REAP will gather researchers and engineers from six countries, who will combine their expertise in biology, chemistry, oncology, material sciences, photonics, and electrical and biomedical engineering in the hope of revealing DTPs in cancer using contrast enhanced multimodal optical imaging. Laser sources for photoacoustic microscopy, photoacoustic tomography, and optical coherence tomography will be developed to enable the design of a two-photon laser scanning optical coherence photoacoustic microscopy system and an optical coherence photoacoustic tomography system. Furthermore, novel photoacoustic detectors using micro-ring resonator will be designed and fabricated, granting improved sensitivity and easier integration of multiple optical imaging modalities into a single system. Innovative algorithms will be developed to reconstruct and analyze the images quickly and automatically. With successful implementation of this four-year project, we can not only gain insight into the mechanisms governing DTPs, but also significantly advance the technology readiness level of contrast agents, lasers, sensors, and image analysis software through joint efforts.

Hybrid integration of semiconductor optical amplifiers with frequency-selective feedback circuits, implemented using low-loss Si3N4 waveguides, enables robust chip-sized lasers with outstanding properties. Deploying ring resonators as a tunable feedback filter provides single-mode operation over a wide wavelength range. Moreover, these rings resonantly enhance the cavity length, which results in ultra-narrow intrinsic linewidth, as low as 40 Hz. Here, we present an overview on state-of-the-art developments regarding these lasers. We compare linewidth and tuning results for different feedback circuit configurations. Finally, we report on the first demonstration of a hybrid-integrated semiconductor laser that operates in the visible wavelength range.

A large number of discrete optical components could be replaced by a photonic integrated circuit in a multi-color laser engine for the visible spectral range. The photonic integrated circuit is based on silicon nitride waveguide technology. We report on the use of silicon nitride (SiN) photonic integrated circuits (PICs) in high-value instrumentation, namely multi-color laser engines (MLEs), a core element of cutting-edge biophotonic systems applied to confocal microscopy, fluorescent microscopy - including super-resolution stimulated emission depletion (STED) microscopy - flow cytometry, optogenetics, genetic analysis and DNA sequencing, to name just a few. These have in common the selective optical excitation of molecules - fluorophores, or, in the case of optogenetics, light-gated ion channels - with laser radiation falling within their absorption spectrum. Unambiguous identification of molecules or cellular subsets often requires jointly analyzing fluorescent signals from several fluorescent markers, so that MLEs are required to provide excitation wavelengths for several commercially available biocompatible fluorophores. A number of functionalities are required from MLEs in addition to sourcing the required wavelengths: Variable attenuation and/or digital intensity modulation in the Hz to kHz range are required for a number of applications such as optical trapping, lifetime imaging, or fluorescence recovery after photobleaching (FRAP). Moreover, switching of the laser between two fiber outputs can be utilized for example to switch between scanning confocal microscopy and widefield illumination modes, for instance, for conventional fluorescence imaging.

We implement a multi-color laser engine with silicon nitride photonic integrated circuit technology, that combines four fluorophore excitation wavelengths (405 nm, 488 nm, 561 nm, 640 nm) and splits them with variable attenuation among two output fibers used for different microscope imaging modalities. With the help of photonic integrated circuit technology, the volume of the multi-color laser engine’s optics is reduced by two orders of magnitude compared to its commercially available discrete optics counterpart. Light multiplexing is implemented by means of a directional coupler based device and variable optical attenuation as well as fiber switching with thermally actuated Mach-Zehnder interferometers. Total insertion losses from lasers to output fibers are in the order of 6 dB at 488 nm, 561 nm, and 640 nm. Higher insertion losses at 405 nm can be further improved on. In addition to the system level results, spectrally resolved performance has been characterized for each of the developed devices.

Four years ago, the EU project PIX4life set out to mature an open access pilot line for silicon nitride integrated photonics, focused on life science applications. The synergies of industrial and academic project partners enabled the creation and validation of a unique pilot line using carefully selected demonstrator projects. Simultaneously, the software infrastructure (process design kits, design tools and building blocks) needed to enable early access of the pilot line through multi-project wafer (MPW) fabrication runs was created. After ten MPW fabrication runs in last three years at two foundries, and successful realization of dozens of designs from the project partners and the external customers, the pilot line is fully operational and ready for open access. In this presentation, we intend to share the experiences we have gained in setting up the pilot line, and to discuss the opportunities and challenges we can expect in future.

Visible diode lasers with wide wavelength tunability and narrow spectral linewidth are of high importance in bio-photonics and metrology. Hybrid integrated diode lasers, using waveguide circuits for spectrally selective feedback, provide wide tunability and sub-100-Hz intrinsic linewidths in a robust chip format. So far, these lasers have only been realized at infrared wavelengths. Here we present the first operation of a hybrid integrated diode laser in the visible. The laser, formed by a diode amplifier which is hybrid integrated with a Si3N4 ring-resonator based feedback circuit, is tunable over 11 nm around 685 nm and delivers 5 mW output power.

An overview of the most recent developments and improvements to the low-loss TriPleX Si3N4 waveguide technology is presented in this paper. The TriPleX platform provides a suite of waveguide geometries (box, double stripe, symmetric single stripe, and asymmetric double stripe) that can be combined to design complex functional circuits, but more important are manufactured in a single monolithic process flow to create a compact photonic integrated circuit. All functionalities of the integrated circuit are constructed using standard basic building blocks, namely straight and bent waveguides, splitters/combiners and couplers, spot size converters, and phase tuning elements. The basic functionalities that have been realized are: ring resonators and Mach–Zehnder interferometer filters, tunable delay elements, and waveguide switches. Combination of these basic functionalities evolves into more complex functions such as higher order filters, beamforming networks, and fully programmable architectures. Introduction of the active InP chip platform in a combination with the TriPleX will introduce light generation, modulation, and detection to the low-loss platform. This hybrid integration strategy enables fabrication of tunable lasers, fully integrated filters, and optical beamforming networks.

Offering open-access silicon photonics-based technologies has played a pivotal role in unleashing this technology from research laboratories to industry. Fabless enterprises rely on the open-access of these technologies for their product development. In the last decade, a diverse set of open-access technologies with medium and high technology readiness levels have emerged. This paper provides a review of the open-access silicon and silicon nitride photonic IC technologies offered by the pilot lines of European research institutes and companies. The paper also highlights upcoming features of these platforms and discusses how they address the long-term market needs.

We are reporting on a Multi-Color Laser Engine (MLE) multiplexing four wavelengths (405 nm, 488 nm, 561 nm, 640 nm) by means of a Photonic Integrated Circuit (PIC) with Silicon Nitride (SiN) waveguides. Multiple building blocks are tested that allow manipulating the light in the waveguides to achieve fiber switching and variable optical attenuation. To slow down facet degradation and extend chip lifetime at near Ultra-Violet (UV) wavelengths (405 nm), a lateral endcap is implemented on chip and tested for reliability. Reasonable coupling and on-chip losses have been achieved in view of a practical use of the technology.

This paper describes the detailed characterization of a novel InP-Si3N4 dual laser module with results revealing relative intensity noise (RIN) as low as -165 dB/Hz and wide wavelength tunability (100 nm). The hybrid coupled laser is deployed in an unamplified 28 GBd 8 level pulse amplitude modulation (PAM) short-reach data center (DC) transmission system. System performance, which is experimentally evaluated in terms of received signal bit error ratio (BER), demonstrates the ability of the proposed laser module to support PAM-8 transmission across a 100 nm tuning range with less than 1 dB variance in receiver sensitivity over the operating wavelength range. Comparative performance studies not only indicate that the proposed source can outperform a commercial external cavity laser (ECL) in an intensity modulation/direct detection (IM/DD) link but also highlight the critical impact of RIN in the design of advanced modulation short-reach systems. Science Foundation Ireland (12/RC/2276_P2, 13/RC/2077_P2, 16/RI/3698, 18/EPSRC/3591, 18/SIRG/5579).

Silicon-Nitride (Si 3 N 4 ) based photonic integrated circuits (PICs) enable a good biophotonic sensing platform. The platforms allows integration of multiple sensor elements and operates over a broad wavelength range. The use of PIC technology allows it to be very sensitive as well as allow for wide dynamic ranges. Combined with (hybrid) integration of sources and detectors make the platform suitable both for high end desktop applications, as well as single use, disposable. The PIC platform and (hybrid) integration are described in this article and examples of biophotonic sensing are shown.

The silicon nitride (Si3N4) planar waveguide platform has enabled a broad class of low-loss planar-integrated devices and chip-scale solutions that benefit from transparency over a wide wavelength range (400–2350 nm) and fabrication using wafer-scale processes. As a complimentary platform to silicon-on-insulator (SOI) and III–V photonics, Si3N4 waveguide technology opens up a new generation of system-on-chip applications not achievable with the other platforms alone. The availability of low-loss waveguides (

Photonic Integrated Circuit technology for visible light can enable new applications which are not possible to realize with existing discrete components. In this paper we will show several examples of passive and active optical functions based on our new waveguide technology for visible light. Examples like wavelength combiners, power splitters, switches, filter components, variable attenuators and modulators demonstrate that the creation of new functionalities and applications become possible by combining more visible-light on-chip functions on a single platform.

Photonics has become critical to life sciences. However, the field is far from benefiting fully from photonics' capabilities. Today, bulky and expensive optical systems dominate biomedical photonics, even though robust optical functionality can be realized cost-effectively on single photonic integrated circuits (PICs). Such chips are commercially available mostly for telecom applications, and at infrared wavelengths. Although proof-of-concept demonstrations for PICs in life sciences, using visible wavelengths are abundant, the gating factor for wider adoption is limited in resource capacity. Two European pilot lines, PIX4life and PIXAPP, were established to facilitate European R and D in biophotonics, by helping European companies and universities bridge the gap between research and industrial development. Through creation of an open-access model, PIX4life aims to lower barriers to entry for prototyping and validating biophotonics concepts for larger scale production. In addition, PIXAPP enables the assembly and packaging of photonic integrated circuits.

This tutorial aims to provide a general overview on the state-of-the-art of photonic integrated circuits (PICs) in the visible and short near-infrared (NIR) wavelength ranges, mostly focusing in silicon nitride (SiN) substrates, and a guide to the necessary steps in the design toward the fabrication of such PICs. The focus is put on bio- and life sciences, given the adequacy and, thus, a large number of applications in this field.

As key enabling technology, photonics has become critical in many fields. Advances in fabrication technologies have realized photonic integrated circuits not only for telecommunication wavelengths but also in the mid-infrared, and very importantly, in the visible. The latter can strongly benefit bio- and life-science applications where visible light is very commonly used in bulky and expensive optical systems. Through PICs Robust optical functionalities can be realized cost-effectively. However, the technology was not openly available until very recently.The pilot line, PIX4life, was established with the aid of the European Union to facilitate European R&D employing visible light PICs for visible applications, targeting mainly health and bio-science applications.

Detailed characterization of a hybrid integrated tunable laser based on micro-ring resonators shows a tuning range of 50 nm with ~40 kHz linewidth. The device demonstrates performance comparable with commercial external cavity lasers in 16QAM coherent system.

Photonic Integrated Circuits (PIC) find increasing use in applications that rely on wavelengths outside of the telecommunication wavelength bands where they originate from. Spectroscopy applications in life science and medical generally use wavelengths covering the full visible, near and short-wave infrared region. In this paper we describe the use of photonic integrated circuits as a spectrometer for spectral tissue sensing, which requires to measure the spectral response of a broad band source, emitting light from 400 to 1700nm, scattered from the tip of a photonic needle that is in close contact with tissue [1-4]. The detected spectral fingerprints in the scattered light enables to distinguish between different tissue constituents and tissue types and may serve as real-time feedback to a physician during an intervention. Using photonic integrated circuits supports the desire to lower the size and increase the usability of such equipment, making it more portable and on the long run even implantable.

We are developing a silicon nitride photonic integrated circuit to replace dichroic mirrors, acousto-optic tunable filters and fiber switches inside a multi-color laser engine aimed towards fluorescent microscopy and flow cytometry. Both the application space and design aspects will be discussed.

Photonic Integrated Circuits (PIC) find increasing use in applications in life science and medical that use wavelengths covering the full visible, near and short wave infrared region. In this paper we describe a PIC spectrometer for spectral tissue sensing, that measures the response of a broad band source, emitting light from 400 to 1700nm, scattered from the tip of a photonic needle that is in close contact with tissue. [1]. The detected spectrum enables to distinguish between different tissue constituents and types and serves as real-time feedback to a physician during an intervention. Using PICs supports the desire to lower the size and increase the usability of such equipment, making it more portable.

Photonic Integrated Circuits (PIC) will change the fundamental paradigms for the design of multi-color laser engines for life sciences. Exemplified with flow cytometry (FCM), integrated optical technology for visible wavelengths will be shown to open a new spectrum of possibilities to control flow cell illumination patterns, such as the number of output spots, the spot size, and even complex patterns generated by interferometry. Integration of additional optical functions such as variable optical attenuation, wavelength division multiplexing or fast shutters adds value to the PIC. TOPTICA is demonstrating integration of PICs in present Multi-color Laser Engine (MLE) architectures. Multiple wavelengths (405nm, 488nm, 561nm, 640nm) are coupled free space into the chip, leveraging its beam steering COOLAC (Constant Optical Output Level Auto Calibration) technology for automatic realignment, thus overcoming the need of fiber input delivery. Once in the waveguide, the light can be redirected and shaped to a desired output pattern and pitch, reducing the need of discrete optical components. In this work, we will discuss the implementation of various building blocks in PIC technology for MLEs and analyze the advantages over current macroscopic counterparts.

Photonic technology is increasingly used in applications in medicine, life and environmental science. Whereas currently many of these applications are implemented using some form of discrete (free-space) optics, much can be gained from a transition to Photonics Integrated Circuits. This follows the trends in the electronics industry where highly integrated electronic circuits have allowed the combination of many different functions in a small form factor. Just as it has done for the electronics industry, integrated optics will lead to smaller, cheaper, more reliable and more user friendly devices.

A novel class of optical waveguides with a box-shaped cross section consisting of a low-index inner material surrounded by a thin high-index coating layer is presented. This original multilayered structure widens the traditional concept of index contrast for dielectric waveguides toward a more general concept of effective index contrast, which can be artificially tailored over a continuous range by properly choosing the thickness of the outer high-index layers. An electromagnetic analysis is reported, which shows that the transverse electric and transverse magnetic modes are spatially confined in different regions of the cross section and exhibit an almost 90degC rotational symmetry. Such unusual field distribution is demonstrated to open the way to new intriguing properties with respect to conventional waveguides. Design criteria are provided into details, which mainly focus on the polarization dependence of the waveguide on geometrical parameters. The possibility of achieving single-mode waveguides with either zero or high birefringence is discussed, and the bending capabilities are compared to conventional waveguides. The feasibility of the proposed waveguide is demonstrated by the realization of prototypal samples that are fabricated by using the emerging CMOS- compatible Si3N4-SiO2 TriPleX technology. An exhaustive experimental characterization is reported, which shows propagation loss as low as state-of-the-art low-index-contrast waveguides (< 0.1 dB/cm) together with enhanced flexibility in the optimization of polarization sensitivity and confirms the high potentialities of the proposed waveguides for large-scale integrated optics.

A compact [200/spl times/200 /spl mu/m/sup 2/] wavelength-selective switch based on thermally tunable SiO/sub 2/--Si/sub 3/N/sub 4/ microring resonators has been designed and realized. The switch supports gigabit filtering applications in access networks. Spectral measurements show an ON-OFF ratio of 12 dB and a channel separation of 20 dB. The 10-Gb/s measurements on a single ring show no degradation of the modulated signal and a theoretical BER (bit-error rate)

This paper will discuss and demonstrate the advantages of laser beam combining using single mode integrated optics based on TriPleX™ waveguide technology. Color combining through integrated optics yields compact, robust an low cost devices.

A new class of integrated optical waveguide structures ("TriPleX") is presented, based on low cost CMOS-compatible LPCVD processing of alternating Si3N4 and SiO2 layers. The technology allows for medium and high index-contrast waveguides that exhibit low channel attenuation. In addition, TriPleX waveguides are suitable for operation at wavelengths from visible (< 500 nm) through the infra-red range (2 μm and beyond). The geometry is basically formed by a rectangular cross-section of silicon nitride (Si3N4) filled with and encapsulated by silicon dioxide (SiO2). The birefringence and minimal bend radius of the waveguide are completely controlled by the geometry of the waveguide layer structures. Experiments on typical geometries show excellent characteristics for telecom wavelengths at ~1300 nm-1600 nm (channel attenuation ≤ 0.06 dB/cm, Insertion Loss (IL) ≤ 0.15 dB, Polarization Dependent Loss (PDL) ≤ 0.1 dB, Group Birefringence (Bg) << 1×10-4, bend radius ≤ 50-100 μm).

We report a reconfigurable four-channel optical add-drop multiplexer for use in access networks. The optical add-drop multiplexer (OADM) is based on vertically coupled thermally tunable Si/sub 3/N/sub 4/--SiO/sub 2/ microring resonators (MRs) and has been realized on a footprint of 0.25 mm/sup 2/. Individual MRs in the OADM can be tuned across the full free-spectral range of 4.18 nm and have a 3-dB bandwidth of 50 GHz.

A fully pigtailed and packaged ultra-compact reconfigurable 4-channel optical add-drop multiplexer is shown based on SiO2/Si3N4 microring resonators. Measurements demonstrate full add/drop capability for 40 Gbit/s datasignal as well as the ability to multicast a channel.

FLAMINGO (flexible multiwavelength optical local access network supporting multimedia broadband services) is a research project supported by the Dutch Technology Foundation, STW. We describe the architecture for the all-optical wavelength-and-time-slotted MAN. Key aspects of this architecture include all-optical packet switching, the ability to put IP packets directly over WDM and the possibility of interfacing with any heterogeneous network.

Photonic integration technologies have spread in the past decade by means of foundry models that mirror the electronic-integrated circuit industry developments of the past century. Several monolithic technologies exist, based on silicon and III–V semiconductors. In this paper, we discuss the current state and forthcoming developments of open access photonic foundries whose technology platforms are based on silicon nitride material. The paper presents various silicon nitride technologies and foundries, alongside with access models supported by generic integration and process design kits. Technical features, enabled by different micro-fabrication processes and tools are summarized. Application examples and developments of forthcoming incorporation into these platforms are outlined.

Silicon-Nitride based Photonic Integrated Circuits (PICs) broaden the application scope of PICs outside of telecommunications where it originated from, since the wavelength range over which a waveguide can be designed matches for instance biophotonic applications usually working in the VIS (400-700nm) and NIR (700-1000nm) range. In this paper we show the latest results our silicon-nitride based sensor platform, that consist of an array of several types of interferometric sensors (Microring resonators, Mach-Zehnder interferometers), that are either used as refractive index, absorption or fluorescence sensors. We show the trade-offs between the different sensor types and show why an asymmetric MZI improves the sensitivity of the sensor platform over the MRR with over a factor of 10 down to the 10-8 RIU level. Furthermore we show that using flip-chipped VCSELs as integrated light source a low cost, disposable device is made. For desktop purposes we show how light sources are fiber coupled to the sensing platform creating a high end measurement system. The complete readout system allows for measuring multiple sensors on the chip, enabling multi-analyte measurements as well as improve the total stability of the measurement platform by using on-chip references. Finally we show an overview of measurement results where the sensor platform is functionalized using different interaction layers both local as well as wafer- scale. The results that the sensor platform can be used in for example liquid (blood and saliva) analysis as well as bacteria detection. The platform can be extended with a microfluidic interface for interaction of the optical layer and fluidics. An added integrated on-chip spectrometer allow additional functionality to the presented sensing platform.

Analog radio-over-fiber links enforce strict laser requirements for optical heterodyne systems. Experimental results show the successful implementation of two free-running, uncorrected micro-ring resonator based tunable lasers in a 60GHz A-RoF heterodyne system over 25km.