Abstract: This invention describes algorithmic and computational approaches to optimize the design and performance of microresonator based ultra-low noise lasers including a reflector or filter comprised of multiple (?3) microresonator rings with different ring radii coupled together through bus waveguides. The enhanced reflector/filter design optimization provides more control over the key parameters, including the suppression ratio of unwanted modes over both a wide wavelength range (supporting wide wavelength tunability) and over the narrow range around the laser wavelength (improving laser singlemode and noise performance), while also enabling the design of specific reflector/filter bandwidth and effective length (delay), supporting the design of an ultra-low noise laser with specific operating performance parameters.

Abstract: This invention provides ultra-low noise lasers with exceptional performance through the use of ultra-low loss microresonator based filters/reflectors including multiple (?3) microresonator rings with different ring radii. The ultra-low loss microresonators provide a long effective laser cavity length enabling very narrow linewidth laser operation, with multiple (?3) microresonators providing extremely high selectivity of the lasing mode over a very wide wavelength range; supporting single wavelength and widely tunable wavelength laser operation. The highly selective and also low loss filter/reflector supports high output power operation of the lasers.

Abstract: The invention provides a new linearized electro-optic modulator in which linearization is achieved by modulating the index of a Bragg grating reflector placed in the arm(s) of a Michelson Interferometer. This grating-assisted Michelson Interferometer (GAMI) modulator operates as either an intensity or amplitude modulator, and is shown to significantly improve the linearity of microwave photonics links. Furthermore, this modulator improves the performance of optical communication systems using advanced modulation formats.

Abstract: This invention removes the need to provide temperature control for an optical time delay chip, which is usually provided by a thermo-electric-cooler, in order to significantly reduce the power dissipation of the device and allow ‘uncooled’ operation. Uncooled operation is achieved by monitoring the temperature of the chip, and changing the tuning of each microresonator within the device in order to continue providing the required time delay as the temperature is varied. This invention takes advantage of the fact that microresonators provide a series of resonant wavelengths over a wide wavelength range, so that the closest resonance wavelength below the operating wavelength can always be tuned up to that wavelength. When the device temperature changes, this is accounted for by both the choice of resonance wavelengths and the tuning for each of the microresonators in the device, in order to keep the correct tunable delay.

Abstract: The invention provides a new linearized electro-optic modulator in which linearization is achieved by modulating the index of a Bragg grating reflector placed in the arm(s) of a Michelson Interferometer. This grating-assisted Michelson Interferometer (GAMI) modulator operates as either an intensity or amplitude modulator, and is shown to significantly improve the linearity of microwave photonics links. Furthermore, this modulator improves the performance of optical communication systems using advanced modulation formats.

Abstract: This invention provides ultra-low noise lasers with exceptional performance through the use of ultra-low loss microresonator based filters/reflectors including multiple (?3) microresonator rings with different ring radii. The ultra-low loss microresonators provide a long effective laser cavity length enabling very narrow linewidth laser operation, with multiple (?3) microresonators providing extremely high selectivity of the lasing mode over a very wide wavelength range; supporting single wavelength and widely tunable wavelength laser operation. The highly selective and also low loss filter/reflector supports high output power operation of the lasers.

Abstract: A system includes a transmitter to multiplex a plurality of modulated optical signals and an unmodulated optical signal and to transmit the plurality of modulated optical signals and the unmodulated optical signal along a transmission path. The system also includes a receiver to de-multiplex each of the plurality of modulated optical signals and the unmodulated optical signal and to demodulate each of the plurality of modulated optical signals with the unmodulated optical signal to coherently detect a modulating signal from each of the plurality of modulated optical signals.

Abstract: This invention provides an optical device comprising a large group of non-uniform resonators operating cumulatively as a ‘super-ring’ to provide a controllable group delay with large bandwidth. The super-ring tuning is performed by a single control. The device may include two super-rings, each includes a large number of resonators with a resonant frequencies centered around ?1 and ?2 respectively. The invention provides multiple ways to improve the delay duration, bandwidth and the tuning speed, and overcomes the issue of non-uniformity of resonance frequency for devices incorporating multiple optical resonators.

Abstract: A laser communication system and method are disclosed. The laser communication system includes a laser receiver system to receive a frequency-shift keyed (FSK) optical signal encoded with a plurality of data signals. The laser receiver system including an FSK differential detection system that includes a plurality of differential detection filters that can each receive the FSK optical signal and generate an output. The FSK differential detection system can demodulate the FSK optical signal into a multi-bit digital code corresponding to a frequency of the FSK optical signal based on the output of each of the plurality of differential detection filters.

Abstract: The present invention relates generally to highly power-efficient quantum cascade sources, such as highly power-efficient quantum cascade lasers having ultra-strong coupling between injector and active regions which may be configured to provide broadband quantum cascade lasers.

Abstract: A system includes an optical Y-junction coupler to receive a first modulated optical signal on a wide input path of the optical Y-junction coupler and to receive a second modulated optical signal on a narrow input path of the optical Y-junction coupler, wherein the optical Y-junction coupler generates a combined optical signal from signals received on the wide input path and the narrow input path. A multimode waveguide receives the combined optical signal from the optical Y-junction coupler and propagates a spatially multiplexed optical output signal along a transmission path.

Abstract: A field concentrating surface enhanced Raman spectroscopy (SERS) platform includes a signal amplifying material and a pattern of apertures extending through the signal amplifying material. The pattern of apertures includes a central aperture, and a plurality of radiation capturing apertures positioned around the central aperture. Each of the radiation capturing apertures has a diameter that is larger than a diameter of the central aperture. The platform further includes a substrate that supports the signal amplifying material and a channel that extends through the substrate. The channel is at least partially aligned with the central aperture that extends through the signal amplifying material.

Abstract: A laser communication system and method are disclosed. The laser communication system includes a laser receiver system to receive a frequency-shift keyed (FSK) optical signal encoded with a plurality of data signals. The laser receiver system including an FSK differential detection system that includes a plurality of differential detection filters that can each receive the FSK optical signal and generate an output. The FSK differential detection system can demodulate the FSK optical signal into a multi-bit digital code corresponding to a frequency of the FSK optical signal based on the output of each of the plurality of differential detection filters.

Abstract: This invention provides a balanced thermal approach to the tuning of an optical time delay device in order to eliminate any long-term time response of the device performance due to thermal time constants of the device, its mount, packaging or electronic temperature control circuits. The invention provides multiple ways to improve the thermal tuning speed of the balanced thermal approach. Additionally, the invention overcomes an issue of microresonator non-uniformity by operating a large group of microresonators as a ‘super-ring’ by tuning the large group together to provide a controllable group delay with large bandwidth.

Abstract: The method and system are disclosed for automatic feedback control of integrated optical quadrature modulator for generation of optical quaternary phase-shift-keyed signal in coherent optical communications. The method comprises the steps of detecting at least a part of an output optical signal from the QPSK modulator, extracting of a particular portion of the output signal in frequency domain, and processing the signal in frequency domain to optimize the transmission of an optical link. The system and method of optical communications in fiber or free space are disclosed that implement the quadrature data modulator with automatic feedback control.

Abstract: The present invention provides a system and method of optical communications that utilize coherent detection technique and optical orthogonal frequency division multiplexing for phase encoded data transmission. In particular the invention addresses a device and method for digital polarization compensation of optical signals with up to 100 Gb/s transmission rate received via an optical link. The polarization compensation operates in two modes: acquisition mode and tracking mode. The polarization recovery is performed at the receiver side using the received digital signal conversion into frequency domain and separate reconstruction of the polarization state in each spectral component.

Abstract: The method and system are disclosed for automatic feedback control of integrated optical quadrature modulator for generation of optical quaternary phase-shift-keyed signal in coherent optical communications. The method comprises the steps of detecting at least a part of an output optical signal from the QPSK modulator, extracting of a particular portion of the output signal in frequency domain, and processing the signal in frequency domain to optimize the transmission of an optical link. The system and method of optical communications in fiber or free space are disclosed that implement the quadrature data modulator with automatic feedback control.

Abstract: A non-line of sight (NLOS) communications system and method are provided that implement orthogonal frequency, division multiplexing. A data generator produces a digital data stream, which is converted into M parallel frequency sub-carrier digital data streams (where M is an integer), each sub-carrier is encoded with data and an Inverse Fast Fourier Transform operation is applied, and an output signal is converted to an analog signal, which is imposed onto an optical beam generated by a light source. The beam is transmitted skywards at an elevation angle above the horizon in at least one direction. The beam is scattered due to Mie and Raleigh effects, forming a scattered waveform. At least a part of the scattered waveform is received by a receiver outputting an electrical signal, which enters a DSP unit. The DSP unit digitizes the electrical signal, performs Fourier transformation and recovers data from M sub-carrier signals.

Abstract: A photo-thermal, interferometric spectroscopy system is disclosed that provides information about a chemical, such as explosives and the like, at a remote location. It may be used for solid residue detection on a surface. The system includes a novel light detector system with a matrix of optical elements focusing portions of a received light beam on input waveguides of an optical combiner. The combiner adjusts the phases of the received beam portions and combines them together to maximize the intensity of an output beam. The output beam is detected by a detector, and information about at least one of, absorption spectrum and concentration of the chemical is recovered. In the preferred embodiment the detector is a coherent detector based on 90-degrees optical hybrid.

Abstract: An optical beam combiner is provided, which allows efficient collection of light for various applications: non-line of sight and free space optical communications, remote sensing, optical imaging and others. A multitude of transverse scattered optical beam portions is captured by the multi-aperture array positioned perpendicular to the beam projection direction. These beam portions are combined first into a single optical waveguide with minimal loss of power. This is achieved by modulating the beam portions phase and coupling ratio of couplers in the optical beam combiner tuned to maximize the final output power. The data is recovered from the received optical beam using coherent detection.