Decentralized diagnostic testing that is accurate, portable, quantitative, and capable of making multiple simultaneous measurements of different biomarkers at the point-of-need remains an important unmet need in the post-pandemic world. Resonator-based biosensors using silicon photonic integrated circuits are a promising technology to meet this need, as they can leverage (i) semiconductor manufacturing economies of scale, (ii) exquisite optical sensitivity, and (iii) the ability to integrate tens to hundreds of sensors on a millimeter-scale photonic chip. However, their application to decentralized testing has historically been limited by the expensive, bulky tunable lasers and alignment optics required for their readout. In this work, we realize, for the first time, a segmented sensor architecture that addresses this important challenge by facilitating resonance-tracking readout using a fixed-wavelength laser. The architecture incorporates an in-resonator phase shifter modulated by CMOS drivers to periodically sweep and acquire the resonance peak shifts, as well as a distinct high-sensitivity sensing region, maintaining high performance at a fraction of the cost and size. The segmented architecture comprises purpose-built resonator segments, with sensitivity dependent on the relative length and waveguide design in the sensing region, and improvements in quality factor and intrinsic limit of detection achievable using low-loss routing waveguides. We show, for the first time, that reading out the segmented sensor with a fixed-wavelength laser can offer similar performance to reading it out with the traditional tunable laser, demonstrating a system limit of detection of 6.1 ± 1.9 × 10−5 RIU as well as immunoassay-based detection of the SARS-CoV-2 spike protein. We anticipate that this sensor architecture will open the door to a new data-rich class of portable, accurate, multiplexed diagnostics for decentralized testing.

Reflow-compatible, facet-attached microlenses (FaMLs) with fiber-to-chip coupling insertion loss < 1 dB are demonstrated, with a misalignment sensitivity of 5 µm at a 1 dB excess loss. As a proof of concept, we demonstrate FaMLs that are capable of adaptively correcting translational placement misalignment of up to 30 µm.

Diamond's unique physical properties make it a versatile material for a wide range of nonlinear and quantum photonic technologies. However, unlocking diamond's full potential as a nonlinear photonic material with nonzero second-order susceptibility, χ^{(2)}≠0, requires symmetry breaking. In this Letter, we use a nanoscale cavity to demonstrate second-harmonic generation (SHG) in diamond, and demonstrate, for the first time, that the magnitude of diamond's effective χ^{(2)} strongly depends on the electronic configuration of defects in the diamond crystal, such as nitrogen-vacancy centers. The modification of χ^{(2)} arises from photoionization from the negative to neutral charge state, and is manifested by quenching of SHG upon green illumination. Toggling the green illumination allows for optical switching of the device's χ^{(2)}. Optical control of χ^{(2)} by defect engineering opens the door for second-order nonlinear processes in diamond.

Organic electro-optic materials have demonstrated promising performance in developing electro-optic phase shifters. Their integration with other silicon photonic processes, nanofabrication complexities, and durability remains to be developed. While the required poling step in electro-optic polymers limits their potential and large-scale utilization, devices made of paraelectric nematic liquid crystals suffer from slow bandwidth. In ferroelectric nematic liquid crystals, we report an additional GHz-fast phase shift that ultimately allows for significant second-order nonlinear optical coefficients related to the Pockels effect. It avoids poling issues and can pave the way for hybrid silicon-organic systems with CMOS foundry compatibility. We report DC and AC modulation efficiencies of  ≈ 0.25 V ⋅ mm (from liquid crystal orientation) and  ≈ 25.7 V ⋅ mm (from the Pockels effect), respectively, an on-chip insertion loss of  ≈ 2.6 dB, and an electro-optic bandwidth of f-6dB>4.18 GHz, employing improved light-matter interaction in a waveguide architecture that calls for only one lithography step.

Despite historical neglect, quantitative hormone measurement is crucial for understanding the menstrual cycle (the “fi fth vital sign”) and conditions in women's health such as endometriosis, fertility, pregnancy loss, and menopause. Because hormone levels fl uctuate and interact dynamically during the menstrual cycle, single or infrequent measurements are insuffi cient and several hormones need to be measured simultaneously. There remains a critical need for longitudinal, high-sensitivity, multi-hormone monitoring to enable meaningful insights and advance women's health, both in research and in the clinic. Current hormone measurement technologies are unable to meet this need and suff er from tradeoff s between quantitative accuracy, multiplexing for simultaneous measurement of multiple markers, and cost/convenience. Lab-based measurements are too expensive and inconvenient for frequent (ideally daily) use, while existing portable technologies like lateral fl ow assays are limited to detecting 3-4 hormone markers. New technologies to quantitatively and conveniently monitor hormone levels would have the potential to catalyze a new era of women's health research as well as give clinicians critical evidence to inform how we diagnose and treat conditions in women's health, revolutionizing the standard of care.

Decentralized diagnostic testing that is accurate, portable, quantitative, and capable of making multiple simultaneous measurements of different biomarkers at the point-of-need remains an important unmet need in the post-pandemic world. Resonator-based biosensors using silicon photonic integrated circuits are a promising technology to meet this need, as they can leverage (1) semiconductor manufacturing economies of scale, (2) exquisite optical sensitivity, and (3) the ability to integrate tens to hundreds of sensors on a millimeter-scale photonic chip. However, their application to decentralized testing has historically been limited by the expensive, bulky tunable lasers and alignment optics required for their readout. In this work, we introduce a segmented sensor architecture that addresses this important challenge by facilitating resonance-tracking readout using a fixed-wavelength laser. The architecture incorporates an in-resonator phase shifter modulated by CMOS drivers to periodically sweep and acquire the resonance peak shifts as well as a distinct high-sensitivity sensing region, maintaining high performance at a fraction of the cost and size. We show, for the first time, that fixed-wavelength sensor readout can offer similar performance to traditional tunable laser readout, demonstrating a system limit of detection of 6.1 x 10-5 RIU as well as immunoassay-based detection of the SARS-CoV-2 spike protein. We anticipate that this sensor architecture will open the door to a new data-rich class of portable, accurate, multiplexed diagnostics for decentralized testing.

This paper presents a novel co-packaging approach through on-chip hybrid laser integration with photonic circuits using photonic wire bonding. The process involves die-bonding a low-cost semiconductor distributed-feedback (DFB) laser into a deep trench on a silicon-on-insulator (SOI) chip and coupling it to the silicon circuitry through photonic wire bonding (PWB). After characterizing the power-current-voltage (LIV) and optical spectrum of the laser, a wavelength-current relationship utilizing its tunability through self-heating a swept-frequency laser (SFL) is developed. Photonic integrated circuit (PIC) resonators are successfully characterized using the SFL method, demonstrating signal detection with a quality factor comparable to measurements conducted with an off-chip benchtop laser.

Photonics offers a transformative approach to artificial intelligence (AI) and neuromorphic computing by enabling low-latency, high-speed, and energy-efficient computations. However, conventional photonic tensor cores face significant challenges in constructing large-scale photonic neuromorphic networks. Here, we propose a fully integrated photonic tensor core, consisting of only two thin-film lithium niobate (TFLN) modulators, a III-V laser, and a charge-integration photoreceiver. Despite its simple architecture, it is capable of implementing an entire layer of a neural network with a computational speed of 120 GOPS, while also allowing flexible adjustment of the number of inputs (fan-in) and outputs (fan-out). Our tensor core supports rapid in-situ training with a weight update speed of 60 GHz. Furthermore, it successfully classifies (supervised learning) and clusters (unsupervised learning) 112 * 112-pixel images through in-situ training. To enable in-situ training for clustering AI tasks, we offer a solution for performing multiplications between two negative numbers.

We investigate the dynamics of quantum-well DFB lasers when they are hybrid- integrated via a photonic wire bond to a silicon photonic integrated circuit (PIC). By controlling the phase and amplitude of self-injection, the PIC stabilizes the laser.

The collection of single-photon emission from a quantum dot (QD) in a Bragg waveguide through a photonic wire bond (PWB) via free-space resonant frequency pumping at 1.6 K is demonstrated. The in-fiber single photons show a small multiphoton contribution, quantified by a low second order photon autocorrelation value of g(corr)((2))(0)=(5.9 +/- 0.8)x10(-3) (background-corrected) or graw((0))((2)) = (9.5 +/- 1.4)x10(-2) (raw data). The decay time of the QD is measured to be tau=440 ps. The PWB obviates the need for in-cryostat alignment of the single-photon source with an optical fiber and thus offers a route to scalable integration of quantum photonic devices in a cryogenic environment. Uniquely, the approach combines the QD-waveguide technique, enabling resonant driving of individual QDs without the need for cross-polarization filtering, and the PWB for deterministic, alignment-free coupling of single-photon sources to optical fibers. The combination of a single-photon source in a ridge waveguide with a photonic wire bond (PWB) connected to the end-facet is demonstrated. After cooling the sample to 1.6 K, decay time and second-order autocorrelation under pulsed, resonant optical excitation are analyzed. The findings herein highlight the possibility of using PWBs at low temperatures as an interface for single-photon collection.image

We investigate the influence of anti-reflection (AR) coating index on the performance of distributed feedback (DFB) lasers when integrated to a fiber using photonic wire bonds (PWBs). We compare the performance of air and polymer-matched AR-coated DFB lasers.

Photoinduced modification of second-harmonic generation mediated by nitrogen vacancy (NV) centres in a diamond cavity is observed. Excitation of NV centres quenches the device's second-harmonic emission, and is attributed to modification of $\chi^{(2)}$ by photoionisation from the negative (NV$^-$) to neutral (NV$^0$) charge states.

Fiber-coupled microdisks are a promising platform for enhancing the spontaneous emission from color centers in diamond. The measured cavity-enhanced emission from the microdisk is governed by the effective volume ($V$) of each cavity mode, the cavity quality factor ($Q$), and the coupling between the microdisk and the fiber. Here we observe photoluminescence from an ensemble of nitrogen-vacancy centers into high $Q/V$ microdisk modes, which when combined with coherent spectroscopy of the microdisk modes, allows us to elucidate the relative contributions of these factors. The broad emission spectrum acts as an internal light source facilitating mode identification over several cavity free spectral ranges. Analysis of the fiber-taper collected microdisk emission reveals spectral filtering both by the cavity and the fiber-taper, the latter of which we find preferentially couples to higher-order microdisk modes. Coherent mode spectroscopy is used to measure $Q\sim 1\times10^{5}$ -- the highest reported values for diamond microcavities operating at visible wavelengths. With realistic optimization of the microdisk dimensions, we predict that Purcell factors of $\sim 50$ are within reach.

Photonic wire bonding is a passive laser-PIC integration process applicable at the wafer scale that offers relaxed alignment and mode mismatch tolerance. We present the first demonstration of a complete laser-PIC package operating in a single mode, with integrated output fiber and thermal tuning of ~1nm.

Developing compute platforms capable of performing computations at high speed is essential for data processing in the next generation of data centers and edge devices. A neuromorphic photonic accelerator on a silicon photonic platform is a promising solution. Compared to silicon photonic data communication transceiver modules, neuromorphic photonic accelerators constitute a large number of active and passive components and optoelectronic devices to handle the parallel processing. Thus, an increased number of optical and electrical interconnects are required, making the packaging of such processors challenging. Moreover, thermal and electrical crosstalk can dramatically degrade the performance of such processors. Thus, packaging a neuromorphic photonic accelerator for efficient processing and data movement requires careful considerations at the chip, module, and board levels. This work investigates the challenges and potential solutions for optical coupling, optical and electrical interconnections, processor-memory communication, and thermal and electrical cross-talk to develop neuromorphic photonic accelerators.

High-performance integrated spectrometers are highly desirable for many applications ranging from mobile phones to space probes. Based on silicon photonic integrated circuit technology, we propose and demonstrate an on-chip speckle spectrometer consisting of a 15 ×15, two-dimensional (2D), disordered microring lattice. The proposed 2D, disordered microring lattice is simulated by the transfer-matrix method. The fabricated device features a spectral resolution better than 15 pm and an operating bandwidth larger than 40 nm. We also demonstrate that, based on the speckle patterns, our device can perform a spectrum classification using machine learning algorithms, which will have a huge potential in fast, intelligent material and chemical analysis.

Biosensors using silicon photonics (SiP) technology have shown great promise, including the potential to bring the accurate, data-rich diagnostics of lab-grade assays to the point-of-need. In this presentation, we will discuss our work to address three key challenges of SiP biosensors. First, we are tuning the photonic design to meet important performance criteria. Next, we review techniques to functionalize SiP devices, and present our integration of microfluidics with the millimeter-scale sensor chips. Finally, we are using electronic-photonic integration to mitigate a key challenge for point-of-need SiP sensors: the cost and size of the readout system.

Silicon photonic (SiP) evanescent-field biosensors aim to combine the information-rich readouts offered by lab-scale diagnostics, at a significantly lower cost, and with the portability and rapid time to result offered by paper-based assays. While SiP biosensors fabricated with conventional strip waveguides can offer good sensitivity for label-free detection in some applications, there is still opportunity for improvement. Efforts have been made to design higher-sensitivity SiP sensors with alternative waveguide geometries, including sub-wavelength gratings (SWGs). However, SWG-based devices are fragile and prone to damage, limiting their suitability for scalable and portable sensing. Here, we investigate SiP microring resonator sensors designed with SWG waveguides that contain a “fishbone” and highlight the improved robustness offered by this design. We present a framework for optimizing fishbone-style SWG waveguide geometries based on numerical simulations, then experimentally measure the performance of ring resonator sensors fabricated with the optimized waveguides, targeting operation in the O-band and C-band. For the O-band and C-band devices, we report bulk sensitivities up to 349 nm/RIU and 438 nm/RIU, respectively, and intrinsic limits of detection as low as 5.1 × 10−4 RIU and 7.1 × 10−4 RIU, respectively. This performance is comparable to the state of the art in SWG-based sensors, positioning fishbone SWG resonators as an attractive, more robust, alternative to conventional SWG designs.