A method for scheduling resources for a Wavelength Division Multiplexed, WDM, Passive Optical Network, PON. The WDM PON comprises a central hub (201) and a plurality of remote Optical Network Terminals, ONTs, (220) handling different types of communications traffic. The method (450) comprises receiving (452) a notification message from the plurality of remote Optical Network Terminals, ONTs, indicating a loading status of the ONT, and allocating (454) one or more slots to a plurality of the ONTs based on the received notification messages from the ONTs, wherein the plurality of ONTs (220) handle different types of communications traffic. The slots (301) are allocated based on the received notification messages as a time slot which is time division multiplexed with further time slots, and the slots are further allocated based on the received notification messages as an optical wavelength of a plurality of optical wavelengths of the WDM PON.

Optical network systems are disclosed, including a system comprising a transmitter including a digital signal processor operable to receive a plurality of independent data streams and output a plurality of digital signals based on the plurality of independent data streams, digital-to-analog circuitry operable to supply a plurality of analog signals based on the plurality of digital signals, a laser operable to supply an optical signal, a modulator operable to receive the optical signal and supply a modulated optical signal based on the plurality of analog signals, including a plurality of optical subcarriers, each of which being associated with a corresponding one of the plurality of independent data streams, a first one of the plurality of optical subcarriers having a first spectral width and a second one of the plurality of optical subcarriers having a second spectral width different than the first spectral width; and a first and a second receiver.

A method and apparatus for wavelength allocation for bidirectional optical access. The wavelength allocation method sets a first central wavelength for the optical path terminal to perform downstream transmission to the optical network unit, and a second central wavelength for the optical network unit to perform upstream transmission to the optical network terminal. At this time, the first center wavelength and the second center wavelength are separated by a predetermined wavelength interval, and the first center wavelength is set larger than the second center wavelength.

A semiconductor laser, an optical transmitter component, an optical line terminal, and an optical network unit. The semiconductor laser includes a substrate, a lower waveguide layer, a lower confining layer, a central layer, an upper confining layer, a grating layer, an upper waveguide layer, and an electrode layer that are sequentially formed on the substrate. The upper confining layer, the central layer, and the lower confining layer in a filtering region form a core layer of the filtering region. The grating layer in the filtering region includes a slanted grating. Thus, a modulation chirp and dispersion of a transmitted optical pulse can be reduced.

Methods, systems, and devices for network communications to reduce optical beat interference (OBI) in upstream communications are described. For example, a fiber node may provide a narrow band seed source to injection lock upstream laser diodes. Therefore, upstream communications from each injection locked laser diode may primarily include the wavelength associated with each seed source. The seed sources may be unique to each end device and configured to minimize OBI. That is, the upstream laser diodes may be generic, but the received seed source may enable upstream communications at varying wavelengths. The fiber node may provide each seed source by filtering (e.g., by a grating filter) a broadband light source.

Embodiments relate to providing simultaneous digital and analog services in optical fiber-based distributed radio frequency (RF) antenna systems (DASs), and related components and methods. A multiplex switch unit associated with a head-end unit of a DAS can be configured to receive a plurality of analog and digital downlink signals from one or more sources, such as a service matrix unit, and to assign each downlink signal to be transmitted to one or more remote units of the DAS. In one example, when two or more downlink signals are assigned to be transmitted to the same remote unit, a wave division multiplexer/demultiplexer associated with the multiplex switch unit can be configured to wave division multiplex the component downlink signals into a combined downlink signal for remote side transmission and to demultiplex received combined uplink signals into their component uplink signals for head-end side transmission.

Digital information can be carried on the fiber leg of an access network using binary modulation. Binary modulated data received at an O/E node can then be modulated onto an analog waveform using quadrature amplitude modulation or some other technique for modulating an analog waveform and transmitted over, for example, the coaxial leg of the network. The O/E node may also receive an analog signal, over the coaxial leg, modulated to carry upstream data from subscriber devices. The O/E node may demodulate the upstream signal to recover the upstream data and forward that upstream data over the fiber leg using a binary modulated optical signal.

Optical network systems are disclosed, including a transmitter comprising a digital signal processor that receives data; circuitry that generate a plurality of electrical signals based on the data; a plurality of filters, each of which receiving a corresponding one of the plurality of electrical signals, a plurality of roll-off factors being associated with a respective one of the plurality of filters; a plurality of digital-to-analog converter circuits that receive outputs from the digital signal processor, the outputs being indicative of outputs from the plurality of filters; a laser that supplies light; and a modulator that receives the light and outputs from the digital-to-analog converter circuits, the modulator supplying a plurality of optical subcarriers based on the outputs of the digital-to-analog converter circuits, such that one of the plurality of optical subcarriers carrying information for clock recovery.

Optical network systems and components are disclosed, including a transmitter comprising a digital signal processor receiving a plurality of independent data streams, and supplying a plurality of digital subcarrier outputs, based on the plurality of independent data streams, and configurable to vary the frequency spacing between two or more of the plurality of digital subcarrier outputs; the transmitter configured to output a modulated optical signal including a plurality of optical subcarriers based on the digital subcarrier outputs wherein based on first ones of the plurality of digital outputs, the first one of the plurality of subcarriers is spectrally spaced from the second one of the plurality subcarriers by a first gap, and based on second ones of the plurality of digital outputs, the first one of the plurality of subcarriers is spectrally spaced from the second one of the plurality of subcarriers by a second gap different than the first.

A passive optical network includes a central office providing subscriber signals; a drop terminal; and a wave division multiplexer. A fiber distribution hub may split or separate out dedicated optical signals from subscriber optical signals between the central office and the drop terminal. The wave division multiplexer separates dedicated optical signals pertaining to a specific dedicated subscriber from other optical signals on the line received at the wave division multiplexer. The wave division multiplexer may be part of a cable or part of an intermediate service terminal.