Abstract: In accordance with embodiments there is proposed an ultrasound sensor device and an ultrasound sensor system configured to perform a method using ultrasound to determine a ratio or concentration of respective gases in a flow of mixed gases. There is provided a method to adapt a distribution system with an ultrasound sensor device and/or an ultrasound sensor system.

Abstract: Optical transmitters and optical receivers utilizing long wave infrared light for use with an earth-orbiting satellite communication system, and a structure including an intracavity optical nonlinear process, are described herein. The transmitters include a pumping laser diode with a fast-axis collimating lens and a pumping wavelength ?0, operating in a continuous wavelength (CW) mode. The transmitters also include a laser cavity having a beam combiner or a dichroic mirror, a laser crystal with a lasing wavelength ?1 and a difference frequency generation orientation patterned semiconductor to generate long wave-IR light. The transmitters also include a second laser at a wavelength ?2, operating in a modulation mode. The receivers have a similar structure to the transmitters, utilizing a sum frequency generation orientation patterned semiconductor to convert long wave-IR light into the short wave-IR.

Abstract: A difference frequency generation optical transmitter and sum frequency generation optical receiver operating in the mid-infrared wavelength range for use in free space optical satellite communications are described. By using mid-infrared light, the transmitter/receiver can mitigate atmospheric scintillation, scattering, and other non-ideal optical effects in the communication channel. This is achieved through the use of nonlinear optical crystals designed for difference frequency generation in the case of the transmitter and sum frequency generation for the receiver. High-speed modulated communication signals can thus be frequency converted to the mid-infrared wavelength range by a relatively low cost, compact and high-power optical communication system.

Abstract: A narrow linewidth mid infrared laser, including a pumping laser diode with a fast-axis compressor and a pumping wavelength ?o; and an optical resonator arranged to receive the pumping wavelength ?o, the optical resonator including a laser crystal with a lasing wavelength ?p, a dichroic mirror, and a nonlinear crystal to generate an idler wavelength ?i.

Abstract: Optical transmitters and optical receivers utilizing long wave infrared light for use with an earth-orbiting satellite communication system, and a structure including an intracavity optical nonlinear process, are described herein. The transmitters include a pumping laser diode with a fast-axis collimating lens and a pumping wavelength ?0, operating in a continuous wavelength (CW) mode. The transmitters also include a laser cavity having a beam combiner or a dichroic mirror, a laser crystal with a lasing wavelength ?1 and a difference frequency generation orientation patterned semiconductor to generate long wave-IR light. The transmitters also include a second laser at a wavelength ?2, operating in a modulation mode. The receivers have a similar structure to the transmitters, utilizing a sum frequency generation orientation patterned semiconductor to convert long wave-IR light into the short wave-IR.

Abstract: In accordance with embodiments there is proposed an ultrasound sensor device and an ultrasound sensor system configured to perform a method using ultrasound to determine a ratio or concentration of respective gases in a flow of mixed gases. There is provided a method to adapt a distribution system with an ultrasound sensor device and/or an ultrasound sensor system.

Abstract: A difference frequency generation optical transmitter and sum frequency generation optical receiver operating in the mid-infrared wavelength range for use in free space optical satellite communications are described. By using mid-infrared light, the transmitter/receiver can mitigate atmospheric scintillation, scattering, and other non-ideal optical effects in the communication channel. This is achieved through the use of nonlinear optical crystals designed for difference frequency generation in the case of the transmitter and sum frequency generation for the receiver. High-speed modulated communication signals can thus be frequency converted to the mid-infrared wavelength range by a relatively low cost, compact and high-power optical communication system.

Abstract: A method of image projection including selecting a set of desired chromaticity coordinates of a projection system, the projection system including a plurality of laser sources; determining a set of parameters of an expected operational environment; and configuring each laser source to have a power ratio and a power spectrum density function generating a normalized power spectrum density function of the projection system having the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2 in the expected operational environment. A projection system including an input device configured to receive a set of desired chromaticity coordinates and a set of operational parameters; a plurality of laser sources each having a power ratio and a power spectrum density function configured to generate a normalized power spectrum density function producing the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2.

Abstract: A method of image projection including selecting a set of desired chromaticity coordinates of a projection system, the projection system including a plurality of laser sources; determining a set of parameters of an expected operational environment; and configuring each laser source to have a power ratio and a power spectrum density function generating a normalized power spectrum density function of the projection system having the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2 in the expected operational environment. A projection system including an input device configured to receive a set of desired chromaticity coordinates and a set of operational parameters; a plurality of laser sources each having a power ratio and a power spectrum density function configured to generate a normalized power spectrum density function producing the set of desired chromaticity coordinates and a wavelength diversity factor of at least 2.

Abstract: A crystal poling apparatus has as ingle-domain ferroelectric substrate (e.g. MgO doped LiNbO3 substrate), a sample holder, a high voltage source, a corona torch, a gas source, a chamber, and at least one vacuum pump. An electrode with a certain structure (e.g. a periodical pattern) is formed on the first surface of the substrate, and the substrate is set with the electrode facing down on top of the sample holder. The electrode is grounded so that high electric field is formed in the area with electrode due to the formation of charges generated by the corona torch on the second surface of the substrate. The charge distribution on the second surface of the substrate is controlled by the high voltage source and the gas source. To achieve the optimized crystal poling, the temperature of the substrate is set by the temperature controller, and the electrode on the first surface of the substrate is isolated by the vacuum pump.

Abstract: An encoder system for encoding a signal according to any number of FEC and/or channel codes comprises a shift register, an array of MOD/XOR stages, and a generator matrix stage for controlling the connections between the shift register and the MOD/XOR stages and altering these connections according to a coding format selected by an encoder selection stage. There is also disclosed a decoder system for decoding a signal encoded according to a number of FEC and/or channel codes comprising a decoding stage, and a generator matrix stage for configuring the decoding stage to a decoding code format to be applied an incoming encoded signal. A decoder selection stage is coupled to the generator matrix stage and selects the decoding code format to be used in the decoding process. The decoder selection stage instructs the generator matrix stage to configure the decoding stage according to the selected decoding code format. There is also disclosed a method for encoding and decoding.

Abstract: An optical sensor has a core, a cladding, and an over-layer. In some embodiments the optical sensor also has a sensing layer. The over-layer acts as a sensitivity enhancement layer, with a refractive index larger than that of the cladding layers. A periodic structure, such as a long-period grating (LPG), is formed in the core. A transmission spectrum of the device shows several notches due to the existence of the LPG. A change in the sensing layer's refractive index and/or thickness results in a shift in the notch wavelengths of the LPG. By choosing proper refractive indices and thicknesses of the core, the cladding and the over-layer, the shift in the notch wavelengths can be significantly enhanced.

Abstract: A communications system employs a HARQ method and, for at least some transmission formats, incremental redundancy (IR) signals. For such formats, the multiple IR signals are derived from a single turbo encoded signal by forming multiple permutations of the encoded signal. The permutations are then converted to the coding rate of the selected transmission format. It is demonstrated by simulation that the present proposal achieves a better performance than the known HARQ techniques, while its implementation is simpler. For certain transmission formats, the transmitted signal in response to a retransmission request is identical to the first transmitted signal.

Abstract: A method of estimating the reliability of decoded message bits in a digital communications system is proposed. Message and tail bits are coded and transmitted across a communications channel. The coded message and tail bits are then decoded and it is determined that the decoded message bits have no error when the decoded tail bits have at least one error.

Abstract: Multipath interference in a received wireless signal is cancelled by generating an estimated duplicate of the interference and subtracting it from the received signal. The interference duplication is performed in a truncated manner, based on a determination of which multipath signals are present, so as to reduce the complexity and processing requirement of the interference duplication. In particular, the present invention proposed that the truncation is based on a determination of which multipath signals are present, and the properties of those signals. In a first case, the truncation is that only interference between selected pairs of paths are cancelled in MPIC. In a second case, for given pairs of paths cancellation is only performed for a subset of the chips in which the corresponding two paths can cause interference.

Abstract: A receiver for a HARQ communication system includes a buffer for storing a signal derived from a message. The signal is transmitted to the receiver at a first coding rate. The receiver also includes a decoder which accepts signals having a second coding rate, and a rate dematcher which converts signals from the first coding rate to the second coding rate. The rate dematcher is arranged to process either a combination of the received signals (in the case that the received signals are noisy versions of identical signals transmitted within the communications network) or simply the set of received signals. In either case, the dematcher forwards the results to the decoder. Provided that the second coding rate is lower than the first coding rate, the amount of memory required by the buffer is reduced by locating the buffer before the rate dematching unit.

Abstract: A wavelength conversion element which can set the wavelength of a pump light to a wavelength longer or shorter than the wavelength of a plurality of signal lights and a wavelength of a plurality of conversion lights present in an optical communication band, and a method for using such a wavelength conversion element are provided. A first pump light with a wavelength ?1 of 1.51 ?m, a second pump light with a wavelength ?2 of 1.57 ?m, and a signal light with a wavelength of ?S of 1.55 ?m are multiplexed in a multiplexer and introduced as an incident light into an optical waveguide of a wavelength conversion element. In the optical waveguide, an SF light with a wavelength ?SF of 0.77 ?m is generated by the SFG of the first pump light with a wavelength ?1 of 1.51 ?m and the second pump light with a wavelength ?2 of 1.57 ?m, the signal light is wavelength converted as a DF light (wavelength 1.53 ?m) by the DFG of the SF light and signal light, and this DF light is outputted as the converted light (wavelength ?C=1.

Abstract: A wavelength conversion element which can set the wavelength of a pump light to a wavelength longer or shorter than the wavelength of a plurality of signal lights and a wavelength of a plurality of conversion lights present in an optical communication band, and a method for using such a wavelength conversion element are provided. A first pump light with a wavelength ?1 of 1.51 ?m, a second pump light with a wavelength ?2 of 1.57 ?m, and a signal light with a wavelength of ?S of 1.55 ?m are multiplexed in a multiplexer and introduced as an incident light into an optical waveguide of a wavelength conversion element. In the optical waveguide, an SF light with a wavelength ?SF of 0.77 ?m is generated by the SFG of the first pump light with a wavelength ?1 of 1.51 ?m and the second pump light with a wavelength ?2 of 1.57 ?m, the signal light is wavelength converted as a DF light (wavelength 1.53 ?m) by the DFG of the SF light and signal light, and this DF light is outputted as the converted light (wavelength ?C=1.

Abstract: A method of estimating the reliability of decoded message bits in a digital communications system is proposed. Message and tail bits are coded and transmitted across a communications channel. The coded message and tail bits are then decoded and it is determined that the decoded message bits have no error when the decoded tail bits have at least one error.

Abstract: A method of estimating fading of a modulated signal transmitted through a pilot channel using a digital filter 20 is disclosed herein.