Abstract: A multi-channel optical transceiver includes a multi-channel transmitter optical subassembly (TOSA), a multi-channel receiver optical subassembly (ROSA), and a dual fiber type direct link adapter directly linked to the multi-channel TOSA and the multi-channel ROSA with optical fibers. The dual fiber type direct link adapter is also configured to receive pluggable optical connectors, such as LC connectors, mounted at the end of fiber-optic cables including optical fibers for carrying optical signals to and from the transceiver. The dual fiber type direct link adapter thus provides the optical input and output to the transceiver for the optical signals received by the ROSA and transmitted by the TOSA. The multi-channel 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 thermally shielded multi-channel transmitter optical subassembly (TOSA) may be used in a multi-channel optical transceiver. The multi-channel TOSA generally includes an array of lasers optically coupled to an arrayed waveguide grating (AWG) to combine multiple optical signals at different channel wavelengths. A plurality of laser array thermal shields are thermally coupled to a temperature control device, such as a thermoelectric cooler (TEC), and thermally shield the respective lasers in the laser array in separate thermally shielded compartments. Each of the lasers may also be individually thermally controlled to provide a desired wavelength, for example, using a heater and/or cooler located in each thermally shielded compartment. 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 thermally isolated multi-channel transmitter optical subassembly (TOSA) may be used in a multi-channel optical transceiver. The multi-channel TOSA generally includes an array of lasers optically coupled to an arrayed waveguide grating (AWG) to combine multiple optical signals at different channel wavelengths. The lasers, and possibly other components, are wire bonded to a thermal isolation bar. The thermal isolation bar provides an electrical connection to external circuitry and is thermally coupled to a temperature control device, such as a thermoelectric cooler (TEC). Thus, the thermal isolation bar electrically connects the lasers to the circuitry while preventing external heat from being conducted to the lasers from outside the TOSA. 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 temperature controlled multi-channel transmitter optical subassembly (TOSA) may be used in a multi-channel optical transceiver. The multi-channel TOSA generally includes an array of lasers optically coupled to an arrayed waveguide grating (AWG) to combine multiple optical signals at different channel wavelengths. A temperature control system may be used to control the temperature of both the array of lasers and the AWG with the same temperature control device, e.g., a thermoelectric cooler (TEC). The multi-channel optical transceiver may also include a multi-channel receiver optical subassembly (ROSA). 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 distortion compensation circuit compensates for distortion generated by one or more non-linear elements such as a laser device and may include a primary signal path for carrying an input signal and one or more secondary signal paths for generating distortion. The distortion compensation circuit may also include one or more controllable phase inverters on at least one of the paths. For example, the secondary signal path may include a distortion generator to produce distortion products from the input signal and a signal controlled phase inverter that inverts the phase of the distortion products. The distortion generator and phase inverter may be combined as an invertible distortion generator. The phase inversion may be controlled in response to a phase inversion control signal generated based on one or more parameters such as temperature.

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 distortion compensation circuit including a configurable delay may be used with one or more non-linear elements, such as a laser, to compensate for distortion generated by the non-linear element(s), for example, in broadband RF applications. Embodiments of the distortion compensation circuit may include a primary signal path with a configurable delay segment and a secondary signal path including at least one distortion generator. The configurable delay segment may be selectively configured to provide different delay settings to accommodate different RF loading conditions such that the delayed RF signal on the primary signal path is aligned with the distortion products generated on the secondary signal path when combined to form an RF signal with distortion compensation.

Abstract: An optical transceiver includes an internal optical fiber coupled to optical sub-assemblies in the transceiver and is capable of maintaining a bend diameter of the internal optical fiber above a minimum bend diameter. The optical transceiver thus allows optical fiber to be used within a relatively small space within a housing of the optical transceiver without significant power loss in the optical signal carried on the optical fiber. The optical transceiver may be a small form-factor pluggable (SFP) transceiver used, for example, in an optical line terminal (OLT) and/or optical networking unit (ONU) in a wavelength division multiplexed (WDM) passive optical network (PON).

Abstract: A distortion compensation circuit with frequency detection may be used with one or more non-linear elements, such as a laser, to compensate for frequency-dependent distortion generated by the non-linear element(s), for example, in broadband multichannel RF applications. Embodiments of the distortion compensation circuit may include a frequency detector circuit that detects changes in frequency loading conditions in the distortion compensation circuit such that distortion compensation may be adjusted to compensate for distortion under different frequency loading conditions. In a multichannel RF system with multiple channel operation modes, for example, the frequency detector circuit may detect changes in the frequency loading condition as a result of changing operation modes.

Abstract: A distortion compensation circuit compensates for distortion generated by one or more non-linear elements such as a laser device and/or an optical fiber and may include a primary signal path for carrying an input signal and a secondary signal paths for generating distortion. The distortion compensation circuit may also include a controllable phase inverters and a tunable filter. For example, the secondary signal path may include a distortion generator to produce distortion products from the input signal and a signal controlled phase inverter that inverts the phase of the distortion products and a tunable filter that adjusts the phase of the frequency dependent distortion. The phase inversion and tunable filter may be controlled in response to control signals generated based on one or more parameters such as, for example, laser power, input RF channel loading, temperature, and fiber length.

Abstract: An external cavity laser array system may be used in a WDM optical system, such as a WDM-PON, for transmitting optical signals at multiple channel wavelengths. The system generally includes a plurality of laser emitters (e.g., gain chips) optically coupled to and separated from respective exit reflectors (e.g., tunable narrow-band reflectors), thereby forming an array of external cavity lasers with extended lasing cavities. The exit reflectors may be distributed Bragg reflectors (DBRs) located in the waveguides in an arrayed waveguide grating (AWG). The laser emitters emit a range of wavelengths including multiple channel wavelengths and the DBRs reflect a subset of channel wavelengths including at least a channel wavelength associated with the laser emitter such that lasing occurs at the subset of channel wavelengths. The AWG then filters the emitted laser light at the associated channel wavelengths.

Abstract: A laser array optical coupling assembly may be used to couple a laser array to an arrayed waveguide grating (AWG), for example, in an optical transmitter in a wavelength division multiplexed (WDM) optical communication system. The laser array optical coupling assembly may include an optical fiber tip array with polished optical fiber tips providing a reduced mode field diameter to improve coupling efficiency with the laser array. The laser array optical coupling assembly may also include a direct coupling of the laser array to the AWG with modified AWG inputs reducing the mode field diameter to improve coupling efficiency with the laser array. The laser array optical coupling assembly may be used, for example, in an optical line terminal (OLT) in a WDM passive optical network (PON) or in other transmitters or transceivers in a WDM system capable of transmitting and receiving optical signals on multiple channel wavelengths.

Abstract: An optical transceiver may include an optical fiber coupling assembly for coupling optical fibers to transmitter and receiver sub-assemblies to increase the number of usable channel wavelengths by reducing an incident angle on a WDM filter without causing unwanted back reflection to a laser. In one example, the optical fiber coupling assembly may be used to increase the number of usable channel wavelengths between the L-band and the C-band. The optical transceiver may be used, for example, in an optical line terminal (OLT) and/or optical networking unit (ONU) in a wavelength division multiplexed (WDM) passive optical network (PON) capable of transmitting and receiving optical signals on multiple channel wavelengths.

Abstract: The subject matter disclosed herein relates to synchronizing network timing. In one particular example, network timing may be synchronized using reflected signals.

Abstract: An optical transceiver includes an internal optical fiber coupled to optical sub-assemblies in the transceiver and is capable of maintaining a bend diameter of the internal optical fiber above a minimum bend diameter. The optical transceiver thus allows optical fiber to be used within a relatively small space within a housing of the optical transceiver without significant power loss in the optical signal carried on the optical fiber. The optical transceiver may be a small form-factor pluggable (SFP) transceiver used, for example, in an optical line terminal (OLT) and/or optical networking unit (ONU) in a wavelength division multiplexed (WDM) passive optical network (PON).

Abstract: A system for reducing clipping may be used between a multichannel RF source and a laser to reduce or correct clipping that might occur in the laser as a result of negative spikes or peaks in a multichannel RF signal. The system generally includes a clipping correction circuit that receives the multichannel RF signal and responsive to the RF signal, prevents one or more of the negative peaks in the RF signal from causing clipping. The clipping correction circuit may either detect an envelope of the RF signal and/or may detect one or more peaks in the RF signal. One or more negative peaks may be prevented from causing clipping by adjusting a bias current provided by a bias control circuit and/or by modifying the RF signal with one or more clipping correction pulses coinciding with one or more negative peaks.

Abstract: A wavelength division multiplexed (WDM) optical system generally includes multi-channel transmitters that transmit optical signals on multiple channel wavelengths in the WDM system. The output of the multi-channel transmitters is filtered to select a unique channel wavelength associated with each of the respective transmitters for multiplexing and transmission in the WDM optical system. One embodiment of a multi-channel transmitter includes a full-spectrum Fabry-Perot (FP) laser that emits light across a range of wavelengths including all of the system channel wavelengths. Another embodiment of a multi-channel transmitter includes a broadly-tunable FP laser that is tunable to emit light across different ranges of wavelengths including subsets of the system channel wavelengths. The WDM optical system may include an arrayed waveguide grating (AWG) for filtering and multiplexing the optical signals output from the transmitters.

Abstract: A laser array mux assembly generally includes an array of laser emitters coupled to an optical multiplexer, such as an arrayed waveguide grating (AWG), with an external partial reflector after the multiplexer. Each of the laser emitters may include a gain region that emits light across a range 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. The reflector reflects at least a portion of the filtered light such that lasing occurs at the channel wavelengths of the reflected light. The laser array mux assembly may be used to generate an optical signal at a selected channel wavelength or to generate and combine optical signals at multiple channel wavelengths.

Abstract: A laser mux assembly generally includes a back reflector selectively coupled to one of the input ports of an optical multiplexer, such as an arrayed waveguide grating (AWG), and at least one laser emitter coupled to an output port. The laser emitter may include a gain region that emits light across a plurality of wavelengths including, for example, channel wavelengths in an optical communication system. The emitted light is coupled into the output port and the AWG or optical multiplexer filters the emitted light from the laser emitter at different channel wavelengths. The back reflector reflects the filtered light at the respective channel wavelength such that lasing occurs at the channel wavelength(s) of the reflected, filtered light. The laser mux assembly may be used, for example, in a tunable transmitter, to generate an optical signal at a selected channel wavelength.

Abstract: An extended cavity Fabry-Perot laser assembly provides relatively narrow mode spacing while allowing relatively high speed optical modulation. The extended cavity Fabry-Perot laser assembly generally includes an exit reflector physically separated from a laser emitter (e.g., a gain chip) to extend the lasing cavity and narrow the mode spacing while maintaining a relatively small gain region in the laser emitter capable of higher speed optical modulation. The extended cavity Fabry-Perot laser assembly may be used in a multi-channel transmitter in a wavelength division multiplexed (WDM) optical system that selects a channel wavelength for the transmitter from among multiple channel wavelengths emitted by the laser assembly. The narrow mode spacing may be less than a WDM channel width, and more specifically, may be less than a channel passband of an arrayed waveguide grating (AWG) or other filter used to select the channel wavelength.