Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

An integrated photonic device may include an image detector that comprises an array of pixels. The device may further include an integrated waveguide and a light coupler comprising a light receiving part optically coupled to the integrated waveguide for receiving a light signal. The light coupler may be adapted for coupling a same predetermined spectral band of the light signal to each of a plurality of pixels of the image detector. The light coupler may include a tapered portion, in which the light coupler tapers outward in a direction of propagation, and an end part comprising an elliptically shaped back reflector for reflecting light propagating along the direction of propagation back through the light coupler toward the integrated waveguide.

The invention enables the complexity and cost of implementing a PMU network and/or a control system to be substantially reduced by eliminating the requirement for power supplies, GPS equipment, and telecommunication equipment at each measurement and/or control location. In the case of implementing a PMU network, creation of synchrophasors is achieved by centralising the determining of phasors and corresponding time-stamps at a location away from the actual measurement locations. Alternatively, or in addition to time-stamping phasors, the invention enables the time-stamping of any received signals and/or measurements derived from those signals. These signals are received from appropriate sensors distributed along optical fibres such as may be incorporated in modern power cables. Likewise, control signals can be communicated along optical fibres such as may be incorporated in modern power cables, and a number of approaches to ensuring control signals are received by the intended control modules are provided. It is envisaged that either or both the PMU network and control system can be implemented in a power network by exploiting existing optical fibre infrastructure in this way. It is also envisaged that control signals can be transmitted dependent on analysis performed on synchrophasors.

Various embodiments of the invention provide systems and methods for low-cost, low-power Array Waveguide Grating (AWG)-based miniaturized Raman spectroscopy for use in non-invasive glucose monitoring systems, such as in wearable devices that require no replenishment of chemicals or enzymes. The AWG may be manufactured using VLSI processing technology, which significantly reduces manufacturing cost and replaces holographic grating as the dispersive component of light. In embodiments, the AWG is integrated with a number of PIN photodiode detectors on a substrate to further reduce cost and signal loss. In embodiments, a prism-coupling method eliminates alignment problems associated with traditional approaches that utilize fiber-coupling methods.

A photo-detection system includes: a photo-detection apparatus including a light-shielding film, an optically-coupled layer, and a photodetector including first and second photo-detection cells; and an arithmetic circuit that generates, based on first signals and second signals, third signals each representing coherence of light having entered a position of each of the first and second photo-detection cells and generates at least one selected from the group consisting of an average value of the third signals, a standard deviation of the third signals, a ratio between the standard deviation and the average value, and a ratio between an average value of a first portion of the third signals based on light having entered the positions of the first photo-detection cells and an average value of a second portion of the third signals based on light having entered the positions of the second photo-detection cells.

Embodiments of the present disclosure may relate to a digitized grating that may include a first unit cell that has a first period and a first length, where the first period includes a first grating element width and a first space between adjacent grating elements, and where the first length includes a number of first periods. The digitized grating may further include a second unit cell that has a second period and a second length, where the second period is different than the first period and includes a second grating element width and a second space between adjacent grating elements, and where the second length includes a number of second periods.

Optical spectrometers may be used to determine the spectral components of electromagnetic waves. Spectrometers may be large, bulky devices and may require waves to enter at a nearly direct angle of incidence in order to record a measurement. What is disclosed is an ultra-compact spectrometer with nanophotonic components as light dispersion technology. Nanophotonic components may contain metasurfaces and Bragg filters. Each metasurface may contain light scattering nanostructures that may be randomized to create a large input angle, and the Bragg filter may result in the light dispersion independent of the input angle. The spectrometer may be capable of handling about 200 nm bandwidth. The ultra-compact spectrometer may be able to read image data in the visible (400-600 nm) and to read spectral data in the near-infrared (700-900 nm) wavelength range. The surface area of the spectrometer may be about 1 mm.sup.2, allowing it to fit on mobile devices.

A multimode laser that generates laser emissions that are transmitted into an optical coupling then an optical filter to test for failures or faults within that optical filter is provided herein. Multimode lasers generate emissions which many different modes are present in the gain curve. Due to this, typical multi-mode laser failure-cases can be observed in the output frequency signal of laser emissions passing through an optical component. By using a spectrometer to analyze the exiting laser wavelengths, specific failure-cases of the optical component can be identified and related to root causes.

An optical array waveguide grating-type multiplexer and demultiplexer according to an embodiment of the present invention comprise: a first substrate, a plurality of first waveguides disposed on the first substrate to be superposed in the vertical direction, which is the thickness direction of the first substrate; a 1-1st cladding layer disposed between the first substrate and a 1-1st waveguide, which is nearest to the first substrate among the plurality of first waveguides; a 1-2nd cladding layer disposed between the plurality of first waveguides; and a 1-3rd cladding layer disposed on a 1-2nd waveguide, which is furthest from the first substrate among the plurality of first waveguides.