An optofluidic router in a low-cost (PDMS) platform for rapid parallel sample analysis

En col·laboració amb la Universitat de Barcelona (UB), la Universitat Autònoma de Barcelona (UAB) i l'Institut de Ciències Fotòniques (ICFO)Optofluidic system for (bio)chemical applications are becoming more demanding in terms of num- ber of control points, number of light sources and readout equipment. So far, most of these sys- tems require several light sources/detectors for suitable performance, increasing their complexity and cost. In this work, we present an easily integrated, fluidically controlled optical router that fa- cilitates coupling of several light sources or detectors. By using PDMS mirrors and phaseguides, the switching liquid is guided and pinned in desired angles, so that the incident light undergoes total internal reflection and can be reflected towards the output channels without any movable parts. The developed router presents ideal performance for lab on a chip applications, achieving switching frequencies between 0.07 ± 0.025 and 4 ± 2 Hz, depending on the flow rate of the switching liquid. The cross-talk levels are at 20 dB from channel output power to static noise level. With the use of parabolic mirrors, channel coupling efficiencies decrease just 2.38 dBm over four channels. The dynamic switching noise reduces the cross-talk levels by 2-5 dB, depending on the incorporation of ink-apertures. The insertion loss of these devices ranges from 17.34 to 25.42 dB. These results prove the viability of the fluidically controlled router in the low-cost PDMS platform. The intended goal of this work has been to simplify and speed up parallel sample analysis with the router integrated into a multiple path photonic component on a single chip. Development on this front is ongoing to rapidly measure methadone concentrations on chip

High-yield parallel transfer print integration of III-V substrate-illuminated C-band photodiodes on silicon photonic integrated circuits

Transfer printing is an enabling technology for the efficient integration of III-V semiconductor devices on a silicon waveguide circuit. In this paper we discuss the transfer printing of substrate-illuminated III-V C-band photodetectors on a silicon photonic waveguide circuit. The devices were fabricated on an InP substrate, encapsulated and underetched in FeCl3, held in place by photoresist tethers. Using a 2x2 arrayed PDMS stamp with a pitch of 500 mu m in x-direction and 250 mu m in y-direction the photodiodes were transfer printed onto DVS-BCB-coated SOI waveguide circuits interfaced with grating couplers. 83 out of 84 devices were successfully integrated

Ultra-sensitive refractive index gas sensor with functionalized silicon nitride photonic circuits

Portable and cost-effective gas sensors are gaining demand for a number of environmental, biomedical, and industrial applications, yet current devices are confined into specialized labs and cannot be extended to general use. Here, we demonstrate a part-per-billion-sensitive refractive index gas sensor on a photonic chip based on silicon nitride waveguides functionalized with a mesoporous silica top-cladding layer. Low-concentration chemical vapors are detected by monitoring the output spectral pattern of an integrated unbalanced Mach-Zehnder interferometer having one coated arm exposed to the gas vapors. We retrieved a limit of detection of 65 ppb, 247 ppb, and 1.6 ppb for acetone, isopropyl alcohol, and ethanol, respectively. Our on-chip refractive index sensor provides, to the best of our knowledge, an unprecedented limit of detection for low gas concentrations based on photonic integrated circuits. As such, our results herald the implementation of compact, portable, and inexpensive devices for on-site and real-time environmental monitoring and medical diagnostics

Vertical-cavity silicon-integrated lasers by bonding and transfer printing

We present the design and performance of the first current-driven hybrid-vertical-cavity silicon-integrated laser with in-plane waveguide emission. We also show results from preliminary work on transfer printing for large-scale integration of such light sources on silicon photonic integrated circuits

Enabling VCSEL-on-silicon nitride photonic integrated circuits with micro-transfer-printing

New wavelength domains have become accessible for photonic integrated circuits (PICs) with the development of silicon nitride PICs. In particular, the visible and near-infrared wavelength range is of interest for a range of sensing and communication applications. The integration of energy-efficient III-V lasers, such as vertical-cavity surface-emitting lasers (VCSELs), is important for expanding the application portfolio of such PICs. However, most of the demonstrated integration approaches are not easily scalable towards low-cost and large-volume production. In this work, we demonstrate the micro-transfer-printing of bottom-emitting VCSELs on silicon nitride PICs as a path to achieve this. The demonstrated 850 nm lasers show waveguide-coupled powers exceeding 100 mu W, with sub-mA lasing thresholds and mW-level power consumption. A single-mode laser with a side-mode suppression ratio over 45 dB and a tuning range of 5 nm is demonstrated. Combining micro-transfer-printing integration with the extended-cavity VCSEL design developed in this work provides the silicon nitride PIC industry with a great tool to integrate energy-efficient VCSELs onto silicon nitride PICs

Transfer-print integration of GaAs p-i-n photodiodes onto silicon nitride waveguides for near-infrared applications

We demonstrate waveguide-detector coupling through the integration of GaAs p-i-n photodiodes (PDs) on top of silicon nitride grating couplers (GCs) by means of transfer-printing. Both single device and arrayed printing is demonstrated. The photodiodes exhibit dark currents below 20 pA and waveguide-referred responsivities of up to 0.30 A/W at 2V reverse bias, corresponding to an external quantum efficiency of 47% at 860 nm. We have integrated the detectors on top of a 10-channel on-chip arrayed waveguide grating (AWG) spectrometer, made in the commercially available imec BioPIX-300 nm platform. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Transfer printing for heterogeneous silicon PICs

Photonic integrated circuits (PICs), implementing optical functions such as light generation, modulation, routing and detection on a single chip, are emerging as a powerful platform to realize miniaturized optical systems. These chips find applications in various fields, ranging from high-speed optical transceivers to disposable biosensors, LiDARs for detection and ranging, spectroscopic analytical sensors, etc. Silicon photonics is the field that is using silicon fabrication technologies, developed over the last decades for advanced electronic integrated circuits, to realize PI Cs. Using this approach advanced PICs can be realized on 200 mm or 300 mm wafers in high volume and at low cost. On the silicon photonics platform many device structures are readily available: Si or SiN waveguides, micro-heaters for tuning/switching, Si or Ge based modulators and photodetectors. However, other optical functions such as light generation require the integration of III-V semiconductors on the silicon wafers. This can be realized using different approaches ranging from hybrid assembly over die-towafer bonding to monolithic integration. Every approach has its advantages and disadvantages. An interesting approach that we are developing is the use of microtransfer- printing technology for the integration of III-V semiconductor devices on a silicon photonic wafer, which is a scalable and minimally-invasive approach