摘要:
A single-port, reflective, optical modulator with internal amplification. In one advantageous embodiment of the present invention, the single-port modulator includes a semiconductor waveguide amplifier with a high reflector at one end. The single-port geometry reduces the high packaging cost associated with two-port modulators, while the internal amplification compensates for splitting and coupling losses. The single-port optical modulator generally includes an input/output port for receiving a light input signal. A modulation region for modulating the light input signal in response to an electrical drive signal is included along with an amplification region for providing amplification of the light input signal. The modulation region and the amplification region include a waveguide for directing the light input signal. A high reflector coupled at one end of the waveguide opposite the input/output port is operable to reflect the light input signal back toward the input/output port, wherein an amplified and modulated light signal is output therefrom.
摘要:
A fiber optic system includes a transmitter for transmitting high-speed streaming electrical data to a receiver for receiving the high-speed data. In order to transmit multiple channels in the system at high-speeds, an electrical data signal is converted into multiple optical sub-signals. Each of the multiple optical sub-signals are transmitted at the common wavelength on multi-spatial mode media. The receiver receives the multiple optical sub-signals as a multi-spatial mode optical signal and separates the multi-spatial mode optical signal into branch signals having a common wavelength. The receiver mixes each of the branch signals with optical carrier waves having the common wavelength and converts the branch signals into electrical signals. Digital signal processing is used to recover the data sub-signals which are used to recover the original data signal.
摘要:
Various apparatus and methods for reducing inter-core crosstalk in a multicore optical fiber are disclosed. A multicore optical fiber may include a plurality of cores capable of transmitting optical signals, and a cladding surrounding the cores, the cladding having a heterogeneous refractive index such that the optical signals propagate at different velocities in different ones of the cores. A multicore optical fiber may include a first length including cores having heterogeneous modal velocities and a second length, adjacent to the first length, including cores having heterogeneous modal velocities, and the cores in the first length are aligned with cores in the second length having a different modal velocity. Inter-core cross talk in a multicore optical fiber may also be reduced by transmitting optical signals through cores of a multicore optical fiber and pumping light into the cores to create unequal modal velocities in the cores.
摘要:
A method for fabricating an optical device wherein the device comprises a first substrate wafer with at least one buried optical waveguide on an approximately flat planar surface of the substrate and a second substrate wafer with at least a second buried optical waveguide. The waveguides so formed may be straight or curved along the surface of the wafer or curved by burying the waveguide at varying depth along its length. The second wafer is turned (flipped) and bonded to the first wafer in such a manner that the waveguides, for example, may form an optical coupler or may cross over one another and be in proximate relationship along a region of each. As a result, three-dimensional optical devices are formed avoiding the convention techniques of layering on a single substrate wafer.
摘要:
A system and method that utilizes digital coding techniques to combine a high-rate data stream with a lower rate side data stream to produce a combined data stream in such a way that the side data can be extracted by an inexpensive, low-bandwidth receiver. The method generally comprises the steps of: combining at least one payload data stream with at least one side data stream into a composite electrical data stream; applying the composite data stream to an optical transmitter to produce an optical signal; detecting the optical signal with an optical receiver having a maximum frequency of operation less than one-half of the rate of the composite data stream; and recovering the side data stream from the electrical output of the optical receiver.
摘要:
A method and apparatus for providing wavelength-cyclic communication services. M wavelength channels are provided to a plurality of add/drop modules in the network, and each of the add/drop modules selects a distinct comb of wavelength channels for provision to a subscriber. The add/drop modules select a comb of wavelength channels such that each selected channel is separated by N wavelength channels from adjacent selected channels. Thus, each add/drop module can select M/N channels for a corresponding subscriber. A passive Fabry-Perot interferometer having controlled dispersion can function as a wavelength selector at each add/drop module. The Fabry-Perot interferometer can have two different materials having different dispersion properties provided in an interference cavity, thereby providing desired tunability characteristics for the interferometer.
摘要:
A tunable bidirectional multiplexer/demultiplexer (MUX/DEMUX) is disclosed for adding and dropping wavelength channels between an optical transmission system and at least one optical transceiver. The MUX/DEMUX includes at least one add port for adding wavelength channels, at least one drop port for dropping wavelength channels, and at least one first optical circulator coupled to the at least one drop port and the at least one add port. The MUX/DEMUX further includes at least one 1×N wavelength-selective switch coupled to the at least one first optical circulator, and at least one second optical circulator coupled to at least one transceiver port on a second side of the at least one wavelength-selective switch, where the optical circulators and switching components are disposed within a common housing. The at least one wavelength-selective switch and ports are configured such that an optical signal communicated from the at least one transceiver port to the at least one add port follows a first optical path, and an optical signal communicated from the at least one drop port to the at least one transceiver port follows a second optical path, where a portion of the first and second optical paths are the same.
摘要:
A method and system for encoding and determining labels in a Dual Polarization (DP) Quaternary Phase Shift Keying (QPSK) signal is provided. A label frame, signature sequence, and data payload are combined using a complementary constant-weight code encoding (CCWC) encoder, the output of which is deinterleaved and differentially precoded to generate a polarized tributary of a DP-QPSK signal. This encoding can be duplicated for a second tributary of the DP-QPSK signal. The label can be determined using one or more polarizers and corresponding low-speed photodetectors, each applied to a copy of the DP-QPSK signal. The strongest output of the photodetectors is then used to determine the label. Alternatively, the DP-QPSK signal can be viewed as having XI, XQ, PH, and PV tributaries. These tributaries can then be translated into XI, XQ, YI, and YQ tributaries are encoded into a standard DP-QPSK signal.
摘要:
A method for fabricating optical devices comprises the steps of preparing a first substrate wafer with at least one buried optical waveguide on an approximately flat planar surface of the substrate and a second substrate wafer with at least a second buried optical waveguide. The waveguides so formed may be straight or be curved along the surface of the wafer or curved by burying the waveguide at varying depth along its length. The second wafer is turned (flipped) and bonded to the first wafer in such a manner that the waveguides, for example, may form an optical coupler or may crossover one another and be in proximate relationship along a region of each. As a result, three dimensional optical devices are formed avoiding conventional techniques of layering on a single substrate wafer. Optical crossover angles may be reduced, for example, to thirty degrees from ninety degrees saving substrate real estate. Recessed areas may be provided in one or the other substrate surface reducing crosstalk in a completed three dimensional crossover device. Three dimensional optical couplers may comprise waveguides of identical or dissimilar characteristics. Moreover, three dimensional optical switches may be formed using the proposed flip and bond assembly process.
摘要:
A photonics package, and methods for its use are disclosed. In one configuration, a collimating lens is disposed between a photonics device and a ferrule containing two optical fibers. Preferably, one of the fibers delivers an optical signal to the photonics device, and the other fiber receives an optical signal from the photonics device. The fibers within the dual-fiber ferrule are located off of the optical axis of the lens so that light emanating from the signal-delivering fiber will be imaged onto the photonics device at a slight angle from the normal and may be reflected at the same angle for coupling into the signal-receiving fiber Preferably, the photonics device is situated at the Fourier plane to facilitate coupling reflected light into the signal-receiving fiber. The function of the photonics package varies with the included photonics device. For example, the package can function as a data receiver, a data transmitter and a data transceiver by incorporating, respectively, a photodetector, an optical modulator, and a transceiver. The photonics package, which can be integrated in optical communications networks, allows for incoming and outgoing signals to be handled on separate fibers, obviating the need for a splitter as required in one fiber systems. A decrease in signal loss throughout the optical communications system can thus be realized.