Abstract: A heart rate detection method includes: acquiring a plurality of time-domain heart rate detection data; if the time-domain heart rate detection data includes a weak interference signal, extracting a first feature point from the time-domain heart rate detection data, and collecting statistics on feature data of the first feature point to determine time-domain heart rate detection data used in calculating heart rate; if the time-domain heart rate detection data includes a strong interference signal, transforming the time-domain heart rate detection data to a frequency domain to obtain a plurality of frequency-domain heart rate detection data, extracting a second feature point from the frequency-domain heart rate detection data, and collecting statistics on feature data of the second feature point to determine frequency-domain heart rate detection data used in calculating heart rate; and calculating the heart rate based on the time-domain or the frequency-domain heart rate detection data.

Abstract: Systems, methods, and software can be used to provide reminding information. In some aspect, a special event is determined to occur. In response to determining that the special event occurs, a network type currently used by a device is acquired. Historical network usage information corresponding to the network type is determined. The network type and a traffic usage situation is outputted based on the historical usage information.

Abstract: A waveguide coupler has a compression region and an expansion region for coupling light between a silicon waveguide and an optical fiber. The compression region receives light from the silicon waveguide and compresses an optical mode of the light. Light is transmitted from the compression region to an expansion region. The expansion region expands the light to have a larger cross section. Light is then transmitted to the optical fiber.

Abstract: An optical receiver, used in wavelength-division multiplexing, has multiple photodetectors per channel. The optical receiver comprises a demultiplexer to separate incoming light into different output waveguides, one output waveguide for each channel. A splitter is used in each output waveguide to split each output waveguide into two or more branches. A separate photodetector is coupled with each branch so that two or more photodetectors are used to measure each channel.

Abstract: A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder and a ridge. In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages having different widths at a given cross section.

Abstract: A waveguide coupler has a compression region and an expansion region for coupling light between a silicon waveguide and an optical fiber. The compression region receives light from the silicon waveguide and compresses an optical mode of the light. Light is transmitted from the compression region to an expansion region. The expansion region expands the light to have a larger cross section. Light is then transmitted to the optical fiber.

Abstract: A method of fabricating a waveguide mode expander includes providing a substrate including a waveguide, bonding a chiplet including multiple optical material layers in a mounting region adjacent an output end of the waveguide, and selectively removing portions of the chiplet to form tapered stages that successively increase in number and lateral size from a proximal end to a distal end of the chiplet. The first optical material layer supports an input mode substantially the same size as a mode exiting the waveguide. One or more of the overlying layers, when combined with the first layer, support a larger, output optical mode size. Each tapered stage of the mode expander is formed of a portion of a respective layer of the chiplet. The first layer and the tapered stages form a waveguide mode expander that expands an optical mode of light traversing the chiplet.

Abstract: A method for eliminating motion interference includes: performing dimensionality reduction on the multi-dimensional acceleration signal to obtain a one-dimensional acceleration signal that represents motion interference; mixing the first signal and the second signal through a plurality of preset coefficients ri respectively, so as to calculate a plurality of mixed signals corresponding to the plurality of preset coefficients; calculating a correlation coefficient between each of the mixed signals and the one-dimensional acceleration signal; obtaining a preset coefficient corresponding to the maximum correlation coefficient among the correlation coefficients and a preset coefficient corresponding to the minimum correlation coefficient among the correlation coefficients; and calculating a signal with motion interference being eliminated from the measurement signal to be processed, according to the first signal, the second signal, the preset coefficient corresponding to the maximum correlation coefficient, and t

Abstract: An integrated optical device includes a photo-detector (such as germanium) optically coupled to an optical waveguide. This photo-detector is deposited on the optical waveguide, and an optical signal propagating in the optical waveguide may be evanescently coupled to the photo-detector. In order to increase the absorption length of the photo-detector, a mirror (such as a distributed Bragg reflection grating) is included in the optical waveguide near the end of the photo-detector. This mirror reflects the optical signal back toward the photo-detector, thereby increasing the absorption of the optical signal by the photo-detector. In addition, absorption may be reduced by using electrical contacts that are electrically coupled to the photo-detector at locations where the optical mode of the optical signal is largely in the underlying optical waveguide, and by using a fingered metal layer to couple to the electrical contacts.

Abstract: An optical filter for attenuating higher-order modes in an optical waveguide includes a shoulder slab formed of a first material having a first index of refraction and disposed on a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction. The shoulder slab defines a near end having a first width, an intermediate section, adjacent to the first end section, and a far end section, adjacent to the intermediate section and opposite the first end section along a direction of beam propagation. The optical filter also includes a waveguide ridge, formed of the first material and disposed atop the shoulder slab, that traverses the shoulder slab, and is configured to guide light of a fundamental mode along the direction of beam propagation from the near end section to the far end section.

Abstract: A polarization-independent, optical circulator is formed in silicon photonics. The polarization-independent, optical circulator uses an optical splitter having two couplers and two waveguides joining the two couplers. One of the two waveguides is thinner than the other to create a large effective index difference between TE and TM modes transmitted through the one waveguide. Polarization rotators, including reciprocal and/or non-reciprocal rotators, are further used to create the optical circulator.

Abstract: A method and device for lightening heavy oil by utilizing a suspension-bed hydrogenation process are provided.

Abstract: A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder and a ridge. In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages having different widths at a given cross section.

Abstract: A method of fabricating a waveguide mode expander includes providing a substrate including a waveguide, bonding a chiplet including multiple optical material layers in a mounting region adjacent an output end of the waveguide, and selectively removing portions of the chiplet to form tapered stages that successively increase in number and lateral size from a proximal end to a distal end of the chiplet. The first optical material layer supports an input mode substantially the same size as a mode exiting the waveguide. One or more of the overlying layers, when combined with the first layer, support a larger, output optical mode size. Each tapered stage of the mode expander is formed of a portion of a respective layer of the chiplet. The first layer and the tapered stages form a waveguide mode expander that expands an optical mode of light traversing the chiplet.

Abstract: A tunable laser has a first mirror, a second mirror, a gain medium, and a directional coupler. The first mirror and the second mirror form an optical resonator. The gain medium and the directional coupler are, at least partially, in an optical path of the optical resonator. The first mirror and the second mirror comprise binary super gratings. Both the first mirror and the second mirror have high reflectivity. The directional coupler provides an output coupler for the tunable laser.

Abstract: A waveguide coupler has a compression region and an expansion region for coupling light between a silicon waveguide and an optical fiber. The compression region receives light from the silicon waveguide and compresses an optical mode of the light. Light is transmitted from the compression region to an expansion region. The expansion region expands the light to have a larger cross section. Light is then transmitted to the optical fiber.

Abstract: A widely tunable laser system includes a substrate, first and second lasers, an output and at least one optical combining device. The first laser is integrated with the substrate, includes a gain medium that includes a first material, and emits light at a wavelength that is tunable within a first wavelength range that is determined at least in part by the first material. The second laser is integrated with the substrate, includes a gain medium that includes a second material, and emits light at a wavelength that is tunable within a second wavelength range that is different from the first wavelength range that is determined at least in part by the second material. The at least one optical combining device is configured to direct light from one or both of the first laser and the second laser to the output.

Abstract: A modulator and a capacitor are integrated on a semiconductor substrate for modulating a laser beam. Integrating the capacitor on the substrate reduces parasitic inductance for high-speed optical communication.

Abstract: A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder made of crystalline silicon and a ridge made of non-crystalline silicon (e.g., amorphous silicon). In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages have different widths and/or thicknesses at a given cross section.

Abstract: A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder and a ridge. In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages having different widths at a given cross section.