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Near-infrared spectroscopy (NIR) is widely used today in applications ranging from monitoring industrial manufacturing processes to assessing the chemical composition and quality of products and materials. However, the challenge remains in reducing size and cost of these spectroscopic devices, while maintaining their sensitivity and robustness. The miniaturisation of spectral sensors is essential to expanding their application beyond dedicated stations in industrial settings and analytical labs, into the hands of non-specialists working on-site and eventually to consumers. The design of current portable NIR sensor systems is mostly inspired by conventional instruments that use gratings or interferometers. The drawback of these approaches is that they are complex to assemble and contain movable parts that are susceptible to shocks and mechanical vibrations.

In this paper, we present significant reductions of optical losses and contact resistances in AgGe-based ohmic contacts to InP membranes. Due to the high solubility of Si in InGaAs and InGaAsP, heavily doped n-type contact layers are grown on InP wafers. This high doping concentration gives rise to annealing-free ohmic contacts and low contact resistances at the level of $10^{-7}\ \Omega\ \textrm{cm}^{2}$ . It also leads to strong band-filling effects in InGaAs and InGaAsP, which result in low optical absorption losses in the contact layer. Combined with the low optical loss of AgGe, a massive reduction of the propagation loss in membrane waveguides is observed compared with other existing solutions. An additional advantage is the minimal influence of thermal treatments during the processing, leading to very stable high-performing contacts.

Displacement sensing at the nanoscale is required in many applications, including accelerometry, mass sensing and atomic force microscopy. Miniaturization of the sensing elements and integration of the read-out is key in achieving low cost, high resolution and high speed. Here, we present a novel integrated nano-opto-electro-mechanical device which potentially has subnanometer resolution for displacement sensing. The proposed device is a waveguide-coupled, micron-sized, double membrane photonic crystal cavity with integrated electro-optical read-out on a single chip.

In this paper, we propose a novel way for 3D packaging of optical and electrical dies for parallel optical interconnections based on wet etched silicon interposer. The process flow of silicon interposer fabrication is demonstrated. Through three steps of deeply wet etching of silicon, a multi-level cavity is formed for embedding and flip-chipping of optical die and electrical die, and the optical through silicon vias for optical I/Os are opened. After flip chip bonding, a designed 50 µm air gap is formed between electronics and optics for thermal isolation. The heat transfer is also simulated to validate the thermal isolation air gap between dies. After fabricating, a 10 Gbps 12-channel receiver is assembled on the silicon interposer, and the sub-module is scaled down to 4 mm by 6 mm. The performance of the fully assembled sub-module is tested on a probe station. Clear eye patterns are captured for each channel. Bit error rate (BER) testing is also performed showing uniform BER with performance matching that of commercial MM receiver.

The indium phosphide (InP) photonic integrated circuit (PIC) industry has been offering sensing solutions on a chip, with high precision and low cost. The major application is sensor signal read-out. Its next generation, where the InP PICs are much smaller and faster, enables new sensing opportunities. We review our recent developments in the next-generation InP PIC, and discuss their potential in optical sensing.

This work reports on the design of a ring resonator with a high quality factor compatible with InP based generic foundry processes. The resonator consists of a spiral delay line, coupled to a waveguide via a Multimode Interference Coupler with unequal splitting ratio. The spiral loss is greatly reduced by using low-doped shallowly etched waveguides with millimeter bending radii. Based on a measured propagation loss of 0.3 dB/cm, a quality factor of 10 6 and an extinction ratio of about 10 dB are expected for a ring length of 80 mm. By folding the ring into a spiral the chip size is reduced significantly, resulting in a footprint of 2.5 mm × 3.6 mm.

We have fabricated InP nanowire array solar cells with an axial p-n junction. Catalyst gold nanoparticles were first patterned into an array by nanoimprint lithography. The nanowire array was grown in 19 minutes by vapor-liquid-solid growth. The sidewalls were in-situ etched by HCl and ex-situ cleaned with a piranha etch. With this cleaning procedure, we could remove the sidewall extrusions and carbon contamination on the nanowire sidewall. We obtained a Voc of 0.68V, a fill factor of 71%, a diode rectification ratio of 107, an ideality factor of 2.12, a solar cell efficiency of 10.2% and a >90% device yield.

Summary form only given. Single laser chips that emit multiple wavelengths simultaneously are interesting for a range of applications including wavelength division multiplexing, optical instrument testing and optical sensing. A number of approaches have been proposed to achieve multiple wavelength emission (MWE) by e.g. using multiple lasers, but they tend to be bulky and/or expensive. Some of these structures need thermal tuning of the emission wavelengths, which is relatively slow and requires precise control of the chip temperature. In this work we report on a novel integrated approach in order to obtain MWE from a single semiconductor laser based on on-chip filtered optical feedback. The layout of our device is shown in Fig.1(a). It consists of semiconductor ring laser (SRL), two arrayed waveguide gratings which are used to split/recombine light into 4 different wavelength channels, four semiconductor optical amplifier gates and passive and active waveguides to connect these different components.We can select either triple wavelength emission, dual wavelength emission (DWE) or single longitudinal mode emission (SME) by properly adjusting the currents in the semiconductor optical amplifier gates of the feedback loop. An advantage of our device is that we can select the lasing longitudinal modes, and thus the emitted wavelengths, in a simple manner by changing the current in the feedback amplifiers. Wavelength selection is done in a non-thermal fashion, which can in principle be done fast. MWE is achieved in a SRL, which has the additional advantage that it can easily be integrated with other photonic components on a chip.Experimentally the device output without feedback is multi-mode above the threshold current (64 mA). SME can be achieved by pumping one gate with a suitable current [1]. When current is applied to two gates at the same time while the SRL is biased above threshold current, SRL shows DWE for a range of currents on gate 4 and gate 2. This DWE can be observed in the optical spectrum shown in Fig.1(b), at the top of this figure we show a schematic plot of the filter passband of each of the gate channels. The selected longitudinal modes are spectrally positioned within the arrayed waveguide gratings filter passbands corresponding to gate 2 and gate 4 which are chosen to be pumped. The two peak wavelengths are λ1 = 1580.788 nm (gate 4 channel), λ2 = 1583.288 nm (gate 2 channel). This DWE can be explained by the fact that a suitable amount of feedback cancels the gain difference between the wavelength channels due to fabrication and material dichroism. By increasing or decreasing the current injected in one of the pumped gates, we notice switching from two modes in the output to one of them. By pumping three gates instead of two and by precise adjustment of the currents in the gates, triple wavelength emission was observed with similar switching behavior to DWE and then to SME just by changing one of the gate currents. In this contribution we will further discuss the precise behavior of the MWE from the device. We will also show results from numerical simulations based on two directional-mode model[2] extended with Lang-Kobayashi terms to take into account for optical feedback. Some of these numerical results are shown in Fig.1(c). We plot in this figure the maxima of the intensities of the three modes when the feedback phase is equal to 0.5π for each mode. The first modes feedback strength η1 is fixed while the feedback strength η2 and η3 of the second and third modes are kept equal η2 = η3 and are increased simultaneously. As can be seen from Fig1.(c), the device output is changing from SME when (η2 = η3) η1. The numerical results are in qualitative agreement with the experimental observations, showing that MWE is obtained when the effective gain (which includes the effects of material gain, losses and feedback) of the longitudinal modes is equal.

Here, we numerically and experimentally demonstrate that, by combining two post-processing methods (multi-bit extraction and bitwise OR-exclusive (XOR) operations). in a single chaotic semiconductor ring laser (SRL), it is possible to generate true random bits with a bit rate up to 40 Gb/s from a chaos bandwidth of ˜ 2 GHz, thanks to the device ability of lasing in two directional modes and the fact that the two mode signals have low correlations. In addition, SRLs can be easily implemented on chip.

We present a chromatic dispersion and bandwidth pre-compensated 112-Gbit/s single side band signal transmitter over 93 km SSMF at 1550 nm using a dual-drive MZM. The proposed scheme is computationally efficient utilising only 21 linear and 11 quadratic taps.

We demonstrate the first waveguide-coupled metal-cavity nanoLED in a III-V photonic membrane bonded to a silicon substrate, which operates at telecommunication wavelengths. The device works under electrical injection and was characterized through a grating coupler.