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We have developed a static Fabry Perot based filter array operating in the mid-infrared range from ~2 to 4.5 μm, matching the absorption region of several volatile organic compounds. Each filter consists of a cavity system formed by two distributed bragg reflectors with a tuning element with varying length in between. The filters with high transmission (>80%) and controllable transmission peak width are integrated with an array of pyroelectric detectors. The robustness, easy-fabrication and the possibility to tune the optical response to a specific application make the integrated filter arrays suitable for compact sensing systems.

We demonstrate a near-infrared (900-1650nm) spectral sensor based on an array of 16 pixels for classifying and quantifying materials and their composition. These pixels consist of resonant-cavity enhanced photodetectors containing a thin absorbing layer, tuning element and cavity. Using a wafer-scale optical lithography process, we achieve a tunable, wavelength-specific response with narrow linewidths of 50nm and high responsivity (R>0.1A/W). The customizability of the response, small-size and robustness make it suitable for portable spectroscopic solutions in a wide variety of applications. The sensing performance is demonstrated on the prediction of moisture in rice with a coefficient of determination of R^2=0.95.

Spectral sensing in the near-infrared range is of increasing interest for application areas ranging from industrial processes to the agri-food sector, as it allows measuring the chemical composition of organic materials in a fast and non-destructive manner. On-field applications demand spectral sensors with a large spectral range, low angular dependence, robust geometry and small footprint, while being manufacturable on large scale at low cost. To meet these requirements, we developed a multi-pixel array of resonant-cavity enhanced detectors using an InP-membrane-on-silicon platform, where each of the 16 pixels provides an individual photoresponse with a number of resonances, which together cover the wavelength range of 800-1700 nm. The pixels consist of two metal mirrors, which enclose an InP p-i-n photodiode with an InGaAs absorber layer and a tuning layer, which varies in thickness to create the individual photoresponses of different pixels. The multi-pixel arrays are fabricated by adhesive wafer bonding followed by a series of lithography steps to define the tuned pixels and metal contacts for the photocurrent read-out. Despite the limited number of measurement channels with broad spectral response, information on the chemical composition of the sample can be directly retrieved using chemometrics. The sensing capabilities for our spectral sensors are demonstrated with two practical application cases: determination of the nutritional information in raw milk and the classification of different plastic types. For both experiments, the photocurrent measurements from the sensor were used directly in regression or classification algorithms based on partial least squares analysis, leading to convincing prediction performance. This shows that the fabricated spectral sensor can retrieve chemical information for a broad set of sensing problems. Simulations have shown that for a specific sensing problem the prediction performance of the spectral sensor can be further improved by an optimized selection of the available spectral responses.

Many high performance computers (HPC) and cloud computing applications rely on distributing tasks among large numbers of virtual and real servers. This implies that advancements in performance of data centers and HPCs is increasingly dependent on connectivity. In order to insure high degree of connectivity at increasing bit rates and distances the demand for large bandwidth-distance product connections is increasing. These can almost exclusively be provided using optical interconnects. Traditionally optical-interconnect come in the form of pluggable transceivers. However the increases in number of connections and bit-rate poses a limit to further scaling (the front-plate bottleneck). A shift towards mid-board optics is in the making but requires solutions which are compact, power efficient and low cost for manufacturing. In this talk we will present our most recent demonstrations of high density optical interconnect solutions as well as high density switches. First some details about the design aspects and advantages of compact electronic switches employing mid-board optical engines will be discussed. Then, for addressing the challenge of low cost optical interconnects, we will give details on our recent work targeting high channel count VCSELs based sub-modules. Results based on 2.5D and 3D assembly on high resistivity silicon will be discussed as well as the use of direct die attach to flexible PCBs for making high density interconnects.

We report a novel component for integrated quantum photonic applications, a waveguide single-photon autocorrelator. It is based on two superconducting nanowire detectors patterned onto the same GaAs ridge waveguide. Combining the electrical output of the two detectors in a correlation card enables the measurement of the second-order correlation function g (2) (W), which realizes the functionality of a Hanbury-Brown and Twiss experiment in a very compact integrated device. Each detector shows a polarization-independent quantum efficiency of ~0.5-1% at 1300 nm. This autocorrelator represents a key building block for quantum photonic integrated circuits including single-photon sources and linear optics. Keywords: Quantum photonic integrated circuits, |HBT in terferometer, WSPDs, waveguide autocorrelators 1. INTRODUCTION Quantum photonic integrated circuits (QPICs) including active components such as single-photon sources and single photon detectors as well as passive components

We present a novel configuration for a photon number resolving detector based on a series array of shunted superconducting nanowires, which has the potential to provide a high dynamic range. The first prototype of the detector consisting of four series elements is demonstrated with the ability to resolve up to four photons in an incident optical pulse at the telecommunicat ion wavelength window. Keywords: photon-number resolving detectors, superconducting single-photon detectors, quantum optics. 1. INTRODUCTION Standard linear optical detectors that generate an electrical response proportional to the intensity of the incident light have their maximum sensitivity in the few hundreds of photons range, limited by the amplifier noise. On the other hand, single photon detectors (SPDs), which are the most sensitive detectors, are strongly nonlinear: One or more photons result in the same output signal. The gap in between these two detection modes can be filled with photon number resolving (PNR) detectors, which have the sensitivity of SPDs and are able to determine the number of photons in a weak optical pulse. Such detectors are greatly desirable not only in the field of quantum information processing and quantum communication, but also in any application dealing with low light levels, such as fluorescence spectroscopy or optical time-domain reflect ometry. The existing appr oaches for realization of PNR detectors, especially in the telecom wavelength range do not meet all the essential requirements of most applications in terms of timing resolution, sensitivity, speed and dynamic range. In this work, we present a new PNR detector based on spatial multiplexing of nanowire superconducting single-photon detectors

Photonic crystal (PC) devices in the InP/InGaAsP/InP planar waveguide system exhibiting narrow bandwidth features were investigated for use as ultrasmall and tunable building blocks for photonic integrated circuits at the telecom wavelength of 1.55 µm. The H1 cavity, consisting of a single PC-hole left unetched, represents the smallest possible cavity in a dielectric material. The tuning of this cavity by temperature was investigated under the conditions as etched and after the holes were infiltrated with liquid crystal (LC), thus separating the contributions of host semiconductor and LC-infill. The shift and tuning by temperature of the MiniStopBand (MSB) in a W3 waveguide, consisting of three rows of holes left unetched, was observed after infiltrating the PC with LC. The samples finally underwent a third processing step of local wet underetching the PC to leave an InGaAsP membrane structure, which was optically assessed through the ridge waveguides that remained after the under etch and by SNOM-probing.

We have compared the gain dynamics of the ground state excitonic transition between undoped and p-doped electrically-pumped InGaAs quantum-dot optical amplifiers, for temperatures from 300K to 20K. A pump-probe differential transmission technique in heterodyne detection with sub-picosecond time resolution was used. The comparison shows that in the gain regime at high temperatures the recovery dynamics of the p-doped sample is slower than in the undoped device operating at the same modal gain, due to a reduced electron reservoir in the excited states. Conversely, at 20K the initial gain dynamics is faster in the p-doped device due to hole-hole scattering. © 2009 SPIE.