Abstract:
A compact multi-channel optical may include a multi-channel transmitter optical subassembly (TOSA), a multi-channel receiver optical subassembly (ROSA) and a circuit board configured and arranged to fit within a relatively small space. The multi-channel ROSA is spaced from the circuit board to allow circuit components to be mounted between the circuit board and the ROSA. The multi-channel ROSA may also be inverted and mounted proximate a transceiver top housing portion, for example, using an L-shaped ROSA support, to transfer heat from the ROSA to the transceiver housing portion. The optical transceiver may be used in a wavelength division multiplexed (WDM) optical system, for example, in an optical line terminal (OLT) in a WDM passive optical network (PON).
Abstract:
A multi-channel receiver optical subassembly (ROSA) such as an arrayed waveguide grating (AWG), with outputs directly optically coupled to respective photodetectors such as photodiodes. In one embodiment, an AWG may be configured such that optical components of the AWG do not interfere with direct optical coupling, and the wire bonding points on the photodiodes may also be configured such that wire bonding does not interfere with direct optical coupling. The photodetectors may also be mounted on a photodetector mounting bar with a pitch sufficiently spaced to allow connection to floating grounds. A passive alignment technique may be used to determine the mounting locations on the photodetector mounting bar such that the photodetectors are aligned with the optical outputs.
Abstract:
A filtered laser array assembly generally includes an array of laser emitters coupled between external modulators and an arrayed waveguide grating (AWG). Each of the laser emitters emits light across a plurality of wavelengths including, for example, channel wavelengths in an optical communication system. The AWG filters the emitted light from each of the laser emitters at different channel wavelengths associated with each of the laser emitters. Lasing cavities are formed between each of the laser emitters and a back reflector coupled to an output of the AWG such that laser output from the laser emitters is provided at the respective channel wavelengths of the reflected, filtered light. The external modulators enable high speed modulation of the laser output. The modulated laser output may then be optically multiplexed to produce an aggregate optical signal including multiple channel wavelengths.
Abstract:
A laser apparatus has a first mirror, a second mirror, at least a portion of which is defined by the first and second mirrors. The laser has an active region located in the laser cavity, which is capable of stimulated emission at one or more wavelengths of light. The second mirror comprises a plurality of dielectric layers arranged in parallel and having a reflectivity band with a peak reflectivity at a peak wavelength, said reflectivity band having a width of less than 1 nm at a reflectivity of 3% less than the peak reflectivity. The laser apparatus may be a tunable laser apparatus in which the peak wavelength of the reflectivity band is adjusted, thereby adjusting the lasing wavelength of the laser. The reflectivity band may be a lasing threshold reflectivity band over which the reflectivity of the second mirror is greater than a lasing threshold reflectivity which is sufficient to permit lasing.
Abstract:
A zigzag waveguide device-based apparatus and method for achieving or maintaining wavelength lock for a tunable laser designed to generate light at a selected one of a plurality of target wavelengths. The apparatus has a reflectively coupled zigzag waveguide device for receiving a portion of light output by the tunable laser, the zigzag waveguide device having a plurality of filters, each having a passband centered at a respective one of the plurality of target wavelengths, whereby said zigzag waveguide device produces a plurality of filtered light outputs. A plurality of photosensors is provided, one for each of said plurality of filters, each said filter positioned to receive a respective one of the plurality of filtered light outputs, each said filter producing a filter output signal related to the intensity of said portion of light in the passband of the corresponding filter. A processor generates, in response to the plurality of filter output signals, a control signal to adjust the lasing wavelength of the tunable laser to achieve or maintain said selected one of the target wavelengths. In one embodiment, the zigzag waveguide device includes a first waveguide that is coupled to the laser to receive light output. A first wavelength filter is coupled to the first waveguide to receive light therefrom. The first wavelength filter transmits a band of wavelengths and reflecting one or more bands of wavelengths. A second waveguide is coupled to the first wavelength filter and receives light reflected from the first wavelength filter. A mirror is coupled to the second waveguide and receives light from the second waveguide. A third waveguide is coupled to the mirror to receive light reflected from the mirror. A second wavelength filter is coupled to the third waveguide to receive light therefrom. The second wavelength filter transmits a band of wavelengths different from the band of wavelengths transmitted by the first wavelength filter and reflects one or more bands of wavelengths. A first photodiode is coupled to receive light transmitted by the first wavelength filter. A second photodiode is coupled to receive light transmitted by the second wavelength filter. A laser wavelength controller is coupled to the tunable laser and is capable of modifying the wavelength of the tunable laser based at least in part on an output of one of the first and second photodiodes.
Abstract:
A monitored laser system includes a laser with a first mirror and an exit mirror. The laser also has a laser cavity defined at least in part by the first mirror and the exit mirror. Within the laser cavity is an active region that contains material that is capable of stimulated emission at one or more wavelengths such that laser light is emitted from the laser. A power source is coupled to the active region. A multiple reflectivity band reflector (MRBR) is coupled to at least a portion of the emitted laser light. The MRBR has at least first and second wavelength bands with reflectivity above a particular reflectivity separated by at least a third wavelength band having reflectivity below the particular reflectivity. A first photodiode is coupled to at least a portion of the filtered laser light and produces an output based on the amount and wavelength of light received. A means for adjusting the emitted wavelength of the laser toward a particular wavelength in one of the at least first, second, and third wavelength bands based at least in part on the output of the first photodiode.
Abstract:
One or more photodiode performance parameters for a photodiode are determined by first determining four data points Iph1, Voc1, Iph2, and Voc2, where Iph1 is a first short-circuit current, and Voc1 is a first open-circuit voltage, for the photodiode under a first illumination condition, and Iph2 is a second short-circuit current, and Voc2 is a second open-circuit voltage, for the photodiode under a second illumination condition. Then, at least one photodiode performance parameter for the photodiode is determined as a function of said four data points.
Abstract:
Low data rate, low power, bi-directional transmissions may be provided over existing physical communication media (e.g., coaxial cables) using a portable network communications module and in the presence of higher bandwidth, higher power primary signals currently being transmitted over the communication media. The low data rate, low power, bi-directional transmissions may be accomplished using spread-spectrum modulated signals that are positioned in frequency relative to the primary signals, such that the low data rate, low power transmissions occur without detectable interference with the primary signals, which include multiplexed narrowband modulated signals. The primary signals may be modulated using quadrature amplitude modulation (QAM) and multiplexed using orthogonal frequency division multiplexing (OFDM) and the spread-spectrum modulated signals may be chirp spread spectrum (CSS) modulated signals modulated using Gaussian frequency shift keying (GFSK). One example of the spread-spectrum modulated signals is implemented using LoRa technology and communication protocols defined by the LoRaWAN standard.
Abstract:
A coaxial cable seizure assembly includes a stamped conductor with a leaf spring receptacle portion to provide a coaxial cable connection inside an HFC network device, such as an HFC node or amplifier. The stamped conductor portion is stamped from a single piece of metal and is located in an insulator portion. The insulator portion may be located inside a housing of the HFC network device adjacent a coaxial cable port such that the leaf spring receptacle portion is aligned with and receives a coaxial cable center conductor pin of a coaxial cable connected to the coaxial cable port. In one embodiment, a coaxial cable seizure assembly further includes a pin portion formed from the same piece of metal as the leaf spring receptacle. In another embodiment, a PCB-mounted coaxial cable seizure assembly further includes a PCB mounting portion formed from the same piece of metal as the leaf spring receptacle.
Abstract:
A forward and reverse test point circuit with a switchable termination may be used to provide testing of forward and reverse RF signals in an RF amplifier before and/or after amplification. The switchable forward and reverse test point circuit includes at least one switchable termination circuit coupled between forward and reverse terminals of a directional coupler and at least one test point. During forward signal testing, the forward terminal is switched to the at least one test point and the reverse terminal is switched to a termination. During reverse signal testing, the reverse terminal is switched to the at least one test point and the forward terminal is switched to a termination. The RF amplifier including the switchable forward and reverse test point circuit may be used in a hybrid fiber-coaxial (HFC) network delivering CATV services and may be capable of amplifying RF signals up to 1.8 GHz.