Abstract: We disclose an optical receiver for direct detection of an intensity-modulated optical signal, the digital signal processor of which employs a clock-recovery circuit capable of reliably recovering the internal clock of the received optical signal without relying on dispersion-compensation processing even if the signal's eye pattern is substantially closed. In an example embodiment, the clock-recovery circuit comprises a frequency-domain phase detector that operates to determine and track in time the sampling phase using only a subset of the digital spectral components corresponding to the received optical signal. The determined sampling phase is then used to synchronize the digital electrical samples of the received optical signal with the internal clock thereof by way of digital interpolation or through appropriate control of the sampling frequency and phase of the receiver's analog-to-digital converter.

Abstract: We disclose an optical receiver for direct detection of an intensity-modulated optical signal, the digital signal processor of which employs a clock-recovery circuit capable of reliably recovering the internal clock of the received optical signal without relying on dispersion-compensation processing even if the signal's eye pattern is substantially closed. In an example embodiment, the clock-recovery circuit comprises a frequency-domain phase detector that operates to determine and track in time the sampling phase using only a subset of the digital spectral components corresponding to the received optical signal. The determined sampling phase is then used to synchronize the digital electrical samples of the received optical signal with the internal clock thereof by way of digital interpolation or through appropriate control of the sampling frequency and phase of the receiver's analog-to-digital converter.

Abstract: It is disclosed an optical coherent receiver for an optical communication network. The optical coherent receiver is configured to receive a modulated optical signal and to process it for generating an in-phase component and a quadrature component. The optical coherent receiver comprises a power adjuster in turn comprising a multiplying unit and a retroactively connected digital circuit. The multiplying unit is configured to multiply the in-phase and quadrature components by in-phase and quadrature gains, respectively, thereby providing power-adjusted in-phase and quadrature components. The digital circuit is configured to compute: a common gain indicative of a sum of the powers of the power-adjusted in-phase and quadrature components; a differential gain indicative of a difference between the powers of the power-adjusted in-phase and quadrature components; and the in-phase and quadrature gains as a product and a ratio, respectively, between the common gain and the differential gain.

Abstract: Various embodiments relate to a method, device, and machine-readable storage medium including: an optical modem, the optical modem being configured to negotiate a format of an optical communication session with a remote optical transceiver via an optical fiber link; and wherein the optical modem is configured to select a transmission optical wavelength channel for transmitting data of the optical communication session in response to sensing the optical fiber link for light emission and determining that the transmission optical wavelength channel is unused based on the sensing.

Abstract: The present application is directed an optical gyroscope. The optical gyroscope includes a substrate including a first and a second waveguide disposed thereon. One or both of the waveguides may be doped with a rare-earth material. A crossing element is disposed between the first and the second waveguides to form a substantially orthogonal connection therebetween. The application is also directed to a system including an optical gyroscope. The application is further directed to a method of observing characteristics of the optical gyroscope.

Abstract: The present invention aims to provide a cyclosporine external preparation showing improved transdermal absorbability of cyclosporine. The present invention provides an external preparation containing cyclosporine and a ketone.

Abstract: A chromatic dispersion compensator to receive a first set of digital signal values produced by sampling an analog signal at a first sampling rate and generate a second set of digital signal values by sampling the first set of digital signal values at a second sampling rate. The chromatic dispersion compensator applies a chromatic dispersion filter and an anti-aliasing filter to the first set of digital signal values.

Abstract: An apparatus includes an optical modulator and an electrical driver. The electrical driver is configured to provide to the modulator an input drive signal comprising multiple input electrical drive levels of a pulse-amplitude modulation (PAM) signal. The electrical driver is further configured to provide unequal spacing between adjacent ones of the multiple input electrical drive levels, and is still further configured to provide a non-zero bias to the input drive signal. The electrical driver may be a component of an optical transmitter, and the input drive signal may be a differential drive signal. The electrical driver may be further configured such that the bias configures the modulator to produce PAM-modulated optical field output levels that are more evenly spaced than the input electrical drive levels.

Abstract: In one embodiment, a filter includes two sets of dielectric resonators mounted in corresponding sets of metallic resonant cavities. Adjoining resonant cavities are separated by a wall that have an opening. Each dielectric resonator of the first and second sets has a post and a single connected pedestal and is mounted within its corresponding cavity so that the post contacts a first cavity wall and the pedestal is separated from the opposing wall by an air gap. Each dielectric resonator of the first set is oriented in a first direction, with its pedestal on the bottom. Each dielectric resonator of the second set is oriented in a second direction, opposite to the first, with its pedestal on the top. The filter's (i) source port couples with a resonator of the first set and (ii) load port couples with a resonator of the second set.

Abstract: In one embodiment, the cavity filter includes a housing defining a cavity, and at least one post projecting from a first interior surface of the housing towards a second interior surface of the housing. The first interior surface faces the second interior surface. The cavity filter further includes a thermo electric cooler disposed on the housing. The thermo electric cooler is configured to one of cool and heat at least a portion of the housing.

Abstract: An apparatus includes a dielectric slab having first and opposing second major surfaces. A planar antenna element is located on the first major surface. A via formed through the dielectric slab is conductively connected to the antenna element. A plurality of solder bump pads is located on the second major surface and is configured to attach the dielectric slab to an integrated circuit.

Abstract: In one embodiment, a filter includes two sets of dielectric resonators mounted in corresponding sets of metallic resonant cavities. Adjoining resonant cavities are separated by a wall that have an opening. Each dielectric resonator of the first and second sets has a post and a single connected pedestal and is mounted within its corresponding cavity so that the post contacts a first cavity wall and the pedestal is separated from the opposing wall by an air gap. Each dielectric resonator of the first set is oriented in a first direction, with its pedestal on the bottom. Each dielectric resonator of the second set is oriented in a second direction, opposite to the first, with its pedestal on the top. The filter's (i) source port couples with a resonator of the first set and (ii) load port couples with a resonator of the second set.

Abstract: An optical receiver having a plurality of optical IQ modulators arranged in a butterfly configuration and configured to operate as an optical polarization de-multiplexer. The optical receiver further has (i) an opto-electric circuit configured to apply optical homodyne detection to an optical input signal received by the optical receiver and (ii) a controller configured to generate one or more control signals for driving the IQ modulators of the plurality based on one or more electrical feedback signals received from the opto-electric circuit.

Abstract: An optical receiver includes an equalizer to generate a plurality of equalization coefficients corresponding to a plurality of frequencies of an optical signal received by the optical receiver. The equalizer zeroes out a first subset of the equalization coefficients corresponding to a first subset of the plurality of frequency components and applies a second subset of non-zero equalization coefficients to the first signal. The optical receiver may also include a chromatic dispersion compensator to generate inverse chromatic dispersion coefficients corresponding to the plurality of frequency components, and to zero out a first subset of the inverse chromatic dispersion coefficients corresponding to the first subset of the plurality of frequency components and further to apply a second subset of non-zero inverse chromatic dispersion coefficients to a second optical signal.

Abstract: A chromatic dispersion compensator to receive a first set of digital signal values produced by sampling an analog signal at a first sampling rate and generate a second set of digital signal values by sampling the first set of digital signal values at a second sampling rate. The chromatic dispersion compensator applies a chromatic dispersion filter and an anti-aliasing filter to the first set of digital signal values.

Abstract: An optical receiver having an electronic dispersion-compensation module with two parallel signal-processing branches configured to provide a greater range of dispersion compensation than that provided by a prior-art device of comparable implementation complexity. In an example embodiment, each of the signal-processing branches includes a respective bank of finite-impulse-response filters that are configured in accordance with a different respective approximation of the group delay that needs to be compensated. The two group-delay approximations used by the filter banks rely on different respective step functions, each having a respective plurality of quantized steps, with the transitions between adjacent steps in one step function being spectrally aligned with the flat portions of the corresponding steps in the other step function.

Abstract: We disclose an optical receiver having a digital filter with an integrated signal re-sampler that enables the receiver to both equalize and re-sample the digital signals generated by the receiver's ADCs configured to run at a fractional sampling frequency. In an example embodiment, the digital filter performs both signal equalization and signal interpolation in the frequency domain by applying an appropriate discrete spectral transfer function to a fractionally oversampled signal and then zero-padding the resulting equalized set of spectral samples. The digital filter re-samples the signal by applying an inverse Fourier transform to the zero-padded set of spectral samples and then truncating and decimating the resulting interpolated set of time-domain samples.

Abstract: The present application is directed an optical gyroscope. The optical gyroscope includes a substrate including a first and a second waveguide disposed thereon. One or both of the waveguides may be doped with a rare-earth material. A crossing element is disposed between the first and the second waveguides to form a substantially orthogonal connection therebetween. The application is also directed to a system including an optical gyroscope. The application is further directed to a method of observing characteristics of the optical gyroscope.

Abstract: In one embodiment, the cavity filter includes a housing defining a cavity, and at least one post projecting from a first interior surface of the housing towards a second interior surface of the housing. The first interior surface faces the second interior surface. The cavity filter further includes a thermo electric cooler disposed on the housing. The thermo electric cooler is configured to one of cool and heat at least a portion of the housing.

Abstract: An optical receiver having an optical IQ modulator configured to generate an optical local-oscillator (OLO) signal for optical homodyne detection of an optical input signal applied to the optical receiver. The optical receiver further has (i) a phase detector configured to generate an electrical measure of the phase difference between the OLO signal and a carrier wave of the optical input signal and (ii) a phase-lock loop configured to drive the optical IQ modulator using the electrical measure. In an embodiment, the phase detector is configured to generate the electrical measure using both I and Q components of the homodyne-detected signal and in a manner that enables the optical receiver to be compatible with the M-QAM modulation format.