Abstract: Methods and apparatus for coherent transmitter calibration are provided that employ direct detection (DD) using one single photodetector (PD). The provided method and apparatus do not require hardware for coherent reception, or additional ADCs for quality control. An additional optical tone is added to a QAM optical signal that is outside the band of the QAM optical signal. The result of this is that after direct detection, there is a correlation between the real and imaginary parts, and the imaginary part can be recovered with a Hilbert transform. The estimated QAM optical signal obtained by direct detection is used to perform a transmitter factory calibration method to calibrate for one or more transmitter impairments and/or to perform in-line self-calibration.

Abstract: The disclosed systems, structures, and methods are directed to monitoring performance of optical networks. Transmitted and received optical channel signal has both low-power gaps and an amplitude modulation pilot tone applied. The low-power gaps are applied at a gap frequency with gap power being lower than a signal power of the optical channel signal. The pilot tone is applied to the optical channel signal at a pilot tone modulation frequency, which is different from the gap frequency. Described methods include determining pilot tone modulation depth based on detected gap power in low-power gaps of the received optical channel signal. Amplifier spontaneous emission and nonlinear noise in optical link are detected separately. This permits determining and monitoring of optical signal-to-noise ratio.

Abstract: The disclosed systems, apparatuses and methods are directed to controlling a difference between a first center frequency of a first optical subcarrier and a second center frequency of a second optical subcarrier of an optical super-channel signal in an optical network. The method comprises modulating the first optical subcarrier at a first optical side component frequency with a first side modulation frequency and modulating the second optical subcarrier at a second optical side component frequency with a second side modulation frequency. The method further comprises detecting a radio-frequency (RF) power at a modulated beat frequency tone in the modified optical signal.

Abstract: The present disclosure relates to methods and apparatus for graphics processing. In some aspects, multiple processing units can be in a graphics processing pipeline of a GPU. The apparatus can also group the multiple processing units into one or more processing unit clusters. In some aspects, each of the one or more processing unit clusters can correspond to one or more context registers. Additionally, the apparatus can determine one or more context states of the one or more context registers in each of the one or more processing unit clusters. Also, the apparatus can implement one or more execution counters corresponding to at least one of the one or more processing unit clusters in the graphics processing pipeline, where each of the one or more execution counters includes an execution value.

Abstract: The present disclosure relates to methods and apparatus of operation of a processing unit. The apparatus can update a first context register of one or more context registers based on a first programming state. In some aspects, the one or more context registers can be associated with at least one processing unit cluster in a graphics processing pipeline of the processing unit. The apparatus can execute a first draw call function corresponding to the first programming state. The apparatus can determine whether at least one additional first draw call function corresponds to the first programming state. In some aspects, the at least one additional first draw call function can follow the first draw call function in the graphics processing pipeline. Also, the apparatus can execute the at least one additional first draw call function when the at least one additional first draw call function corresponds to the first programming state.

Abstract: The present disclosure relates to methods and apparatus of operation of a processing unit. The apparatus can update a first context register of one or more context registers based on a first programming state. In some aspects, the one or more context registers can be associated with at least one processing unit cluster in a graphics processing pipeline of the processing unit. The apparatus can execute a first draw call function corresponding to the first programming state. The apparatus can determine whether at least one additional first draw call function corresponds to the first programming state. In some aspects, the at least one additional first draw call function can follow the first draw call function in the graphics processing pipeline. Also, the apparatus can execute the at least one additional first draw call function when the at least one additional first draw call function corresponds to the first programming state.

Abstract: The disclosed systems, structures, and methods are directed to monitoring performance of optical networks. Transmitted and received optical channel signal has both low-power gaps and an amplitude modulation pilot tone applied. The low-power gaps are applied at a gap frequency with gap power being lower than a signal power of the optical channel signal. The pilot tone is applied to the optical channel signal at a pilot tone modulation frequency, which is different from the gap frequency. Described methods include determining pilot tone modulation depth based on detected gap power in low-power gaps of the received optical channel signal. Amplifier spontaneous emission and nonlinear noise in optical link are detected separately. This permits determining and monitoring of optical signal-to-noise ratio.

Abstract: In a powered device (PD), four MOSFETs are used in a rectifier circuit. The four MOSFETs are disposed based on a premise that an electric potential of a contact pair 1-2 is lower than that of a contact pair 3-6 and an electric potential of a contact pair 7-8 is lower than that of a contact pair 4-5, so that a PoE current of each contact group passes through only two of the MOSFETs but does not pass through a diode.

Abstract: An embodiment method includes multiplexing light emitted by the plurality of optical transmitters to provide a multiplexed optical signal; propagating the multiplexed optical signal through an optical interleaver from a first port thereof to a combined port thereof and back to a second port thereof; and detecting an optical signal at the second port of the optical interleaver.

Abstract: In a powered device (PD), four MOSFETs are used in a rectifier circuit. The four MOSFETs are disposed based on a premise that an electric potential of a contact pair 1-2 is lower than that of a contact pair 3-6 and an electric potential of a contact pair 7-8 is lower than that of a contact pair 4-5, so that a PoE current of each contact group passes through only two of the MOSFETs but does not pass through a diode.

Abstract: An embodiment method includes multiplexing light emitted by the plurality of optical transmitters to provide a multiplexed optical signal; propagating the multiplexed optical signal through an optical interleaver from a first port thereof to a combined port thereof and back to a second port thereof; and detecting an optical signal at the second port of the optical interleaver.

Abstract: A system for monitoring optical signal-to-noise ratio (OSNR) is provided. In some specific examples, the system may use a pilot tone power of a signal modulated with pilot tone to derive the pure signal power and the variance of the whole electric field to derive the total power (pure signal power plus amplified spontaneous emission (ASE) power of the signal). The ASE power can be obtained by subtracting the pure signal power from the total power (ASE+pure signal). Once the ASE power and the pure signal power are known, the OSNR can be calculated.

Abstract: A system for monitoring optical signal-to-noise ratio (OSNR) is provided. In some specific examples, the system may use a pilot tone power of a signal modulated with pilot tone to derive the pure signal power and the variance of the whole electric field to derive the total power (pure signal power plus amplified spontaneous emission (ASE) power of the signal). The ASE power can be obtained by subtracting the pure signal power from the total power (ASE+pure signal). Once the ASE power and the pure signal power are known, the OSNR can be calculated.

Abstract: An optical transceiver is provided with an optical front end for receiving signal light comprising an optical sub-channel, and for providing an electrical signal based on the signal light; a light source optically coupled to the optical front end for providing local oscillator light thereto for mixing with the signal light; an electro-optical modulator coupled to the light source for receiving output light therefrom and for modulating the output light with digital information to obtain modulated light; and a signal processor operably coupled to the optical front end. The signal processor is configured for processing the electrical signal to obtain a frequency offset of the sub-channel; and adjusting an optical frequency of the modulated light based on the frequency offset. When applied to a multiple-access environment, this may allow access nodes to generate optical sub-channels in the uplink direction using the downlink optical signal as an optical frequency reference.

Abstract: An optical transceiver is provided with an optical front end for receiving signal light comprising an optical sub-channel, and for providing an electrical signal based on the signal light; a light source optically coupled to the optical front end for providing local oscillator light thereto for mixing with the signal light; an electro-optical modulator coupled to the light source for receiving output light therefrom and for modulating the output light with digital information to obtain modulated light; and a signal processor operably coupled to the optical front end. The signal processor is configured for processing the electrical signal to obtain a frequency offset of the sub-channel; and adjusting an optical frequency of the modulated light based on the frequency offset. When applied to a multiple-access environment, this may allow access nodes to generate optical sub-channels in the uplink direction using the downlink optical signal as an optical frequency reference.

Abstract: A graphics processing unit (GPU) may perform a binning pass to determine primitive-tile intersections for a plurality of primitives and a plurality of tiles making up a graphical scene, including performing low-resolution z-culling of representations of the plurality of primitives based at least in part on a first set of culling z-values each having a first test size to determine a first set of visible primitives from the plurality of primitives. The GPU may further perform a rendering pass to render the plurality of tiles based at least in part on performing the low-resolution z-culling of representations of the first set of visible primitives based at least in part on a second set of culling z-values that represents a second test size to determine a second set of visible primitives from the first set of visible primitives, wherein the first test size is greater than the second test size.

Abstract: A graphics processing unit (GPU) may determine a workload of a fragment shader program that executes on the GPU. The GPU may compare the workload of the fragment shader program to a threshold. In response to determining that the workload of the fragment shader program is lower than a specified threshold, the fragment shader program may process one or more fragments without the GPU performing early depth testing of the one or more fragments before the processing by the fragment shader program. The GPU may perform, after processing by the fragment shader program, late depth testing of the one or more fragments to result in one or more non-occluded fragments. The GPU may write pixel values for the one or more non-occluded fragments into a frame buffer.

Abstract: An optical transceiver using a modulator biased to a non-linear region of the modulator's power transfer function can extend the possible transmission distance of intensity modulated direct detection (IMDD) n-level pulse amplitude modulated (PAM-n) signals. A non-linear look-up-table may compensate for non-linear characteristics of the modulator. An adaptive decision threshold look-up-table may be used to provide adaptive decision levels at the receiver.

Abstract: The present applies to digital wavelength converters that convert, independently of the format in which optical data may be encoded, an input waveform at a first wavelength to an output waveform at a second wavelength. When operating in an environment where an input waveform has a pilot tone associated thereto, the method and system of the present disclosure allows for the removal of the pilot tone from the input waveform, and also allows for the addition of another pilot to the output waveform.

Abstract: An optical transceiver using a modulator biased to a non-linear region of the modulator's power transfer function can extend the possible transmission distance of intensity modulated direct detection (IMDD) n-level pulse amplitude modulated (PAM-n) signals. A non-linear look-up-table may compensate for non-linear characteristics of the modulator. An adaptive decision threshold look-up-table may be used to provide adaptive decision levels at the receiver.