834 results about "Arrayed waveguide grating" patented technology

The invention relates to high power semiconductor lasers based on a laser diode array waveguide grating (DAWG) in which the wavelength is stabilized using an array waveguide grating (AWG) in an external cavity configuration. Another aspect of the present invention relates to techniques for efficiently coupling optical gain element arrays to an AWG. Another feature provides for the efficient and brightness-conserving combination of multiple high power DAWG lasers into a single output.

An optical coherent detector that employs an interleave-chirped arrayed waveguide grating (AWG). The AWG has a periodic chirp pattern that enables the AWG to function as an optical 90-degree hybrid. If the AWG is implemented using a birefringent material, then the AWG can also function as a polarization demultiplexer. In one embodiment, the AWG is designed to simultaneously function as a wavelength demultiplexer, a polarization demultiplexer for each wavelength-division-multiplexed (WDM) signal component, and a 90-degree hybrid for each polarization-division-multiplexed component of each WDM signal component.

This invention provides a system that combines a wavelength multiplexer with an FM discriminator for chirp reduction and wavelength locker in a filter to produce a wavelength division multiplexed signal with reduced chirp. A partially frequency modulation laser signal is converted into a substantially amplitude modulation laser signal. This conversion increases the extinction ratio of the input signal and further reduces the chirp. A wavelength division multiplexing (WDM) method is used for transmitting high capacity information through fiber optics systems where digital information is carried on separate wavelengths through the same fiber. Separate transmitters normally generate their respective signals that are transmitted at different wavelengths. These signals are then combined using a wavelength multiplexer to transmit the high capacity information through the fiber optic system. Various technologies can be used to multiplex the signals such as, for example, thin film filters, or arrayed waveguide gratings. In a WDM system, a wavelength locker may also be used that fixes the center wavelength of a transmitter to a reference. Wavelength lockers may include etalons or fiber gratings, either of which provides a reference wavelength. A control circuit typically compares the wavelength of the transmitter to the reference. An error signal adjusts the transmitter format wavelength by varying temperature or by other means to keep it locked to the reference wavelength.

A fiber optic communication system includes a device of switching and setting wavelength of optical signals used in communication by network-node equipments, which sets the mapping of the wavelength of the optical signal used in communication by the network node equipments, and the input / output ports of an array waveguide grating (AWG), so as to construct a predetermined logical network topology by a plurality of network node equipments which are connected via optical fibers to the array waveguide grating that outputs optical signals inputted to optical input ports, to predetermined optical output ports in accordance with the wavelength thereof. As well as enabling a simple construction, it is easy to realize flexible network design, construction, and operation, and different network groups can also be easily connected to each other. Moreover, a fiber optic communication system having robust security and which can be stably operated even at the time of failure is realized at low cost.

The present invention discloses a network architecture for upgrading a legacy time division multiplexing-passive optical network (TDM-PON) to a wavelength division multiplexing-passive optical network (WDM-PON) based next-generation passive optical network (next-generation PON), wherein the legacy TDM-PON comprises: a central office (CO) having a first optical line termination (OLT); a remote node (RN) having a splitter; a single mode fiber (SMF) connecting the first OLT and the splitter; and a first group of one or more optical network terminations (ONTs) being connected to the splitter by a first group of one or more distribution fibers, and wherein the network architecture further comprises: in case that the next-generation PON is a WDM-PON, a first apparatus for combining and splitting wavelength bands being positioned between the SMF and the first OLT, in order to add a second OLT to be used for the WDM-PON within the CO or within another CO which is located in a position different from the CO, while sharing the SMF; a second apparatus for combining and splitting wavelength bands being positioned at a front terminal of the splitter; and an arrayed waveguide grating (AWG) being connected to the second apparatus for combining and splitting wavelength bands within the RN, and being connected to a second group of one or more ONTs by a second group of one or more distribution fibers within the RN or within another RN which is located in a position different from the RN.

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.

An optical coupling arrangement has a first transition region having a plurality of first segmented waveguides and a plurality of transverse segments of alternating indices of refraction with at least some of the transverse segments traversing the first segmented waveguides. The first segmented waveguides are formed by core segments in some of the transverse segments. The arrangement may also have a second transition region having a plurality of second segmented waveguides each aligned with a respective one of the first segmented waveguides. The arrangement is manufactured with a high production yield and is used in an optical coupling device for combining / splitting optical signals to reduce the insertion loss. The optical coupling device is also used in other devices such as Mach-Zehnder devices and arrayed waveguide grating demultiplexers / multiplexers.

The present invention is directed to the provision of a wavelength division multiplexing optical transmission apparatus and, more particularly, to a wavelength division multiplexing optical transmission apparatus having high wavelength stability unaffected by the temperature characteristics, aging, etc. of an arrayed-waveguide grating (AWG) and its peripheral components. The wavelength division multiplexing optical transmission apparatus comprises: an arrayed-waveguide grating 10 having operating input / output ports and an input dummy port; a light emitting means 21 for generating a pilot signal to be input to the input dummy port; a light detecting means 22 for monitoring the pilot signal contained in a wavelength division multiplexed signal output from the operating output port; and a temperature control circuit 11 for controlling the temperature of the arrayed-waveguide grating in such a manner as to cancel the amount of wavelength fluctuation occurring in the arrayed-waveguide grating and detected by monitoring the pilot signal.

The encoder / decoder design for spectrum-encoded optical CDMA systems uses waveguide circuits monolithically integrated on one chip to fulfill essential encoding and decoding functions. The integrated device functions as a 1x2 wavelength selective Mach-Zehnder interferometer switch to encode the input broadband light source and to decode the transmitted spectrally encoded signals. The device comprises a frontal 3-dB coupler, a double-ended arrayed-waveguide grating (AWG), and arrays of thermooptic phase shifters and attenuators, together with their symmetric images reflected from the high-reflection coated facet, to realize all required functionality. The thermooptic phase shifters and attenuators are programmable through electronic interface to realize programmable encoding and decoding capabilities. The attenuators are used to equalize the powers and to increase the ON / OFF extinction ratio of all spectral chips.

The structure comprises the array of the wave-guide grating as well as the input and output optical fiber array, which is aimed at and coupled to the array of the input and output wave-guide in the array of the wave-guide grating. The array of the wave-guide grating and the input and output optical fiber array are integrated on the same silicon substrate. The self-alignment method is adopted in the invention to carry out the end surface coupling between the input and output wave-guide in the array of the wave-guide grating and the optical fiber array. The optical fiber array is prepared by using the adhesive agent to bond the array of the V or U shaped groove on the substrate, the upper cover piece and the monomode fiber with multiple cores.

In a Wavelength Division Multiplexed Passive Optical Network (WDM-PON) including, a system for distributing uplink, downlink and RF / Video broadcast signalling. An Array Waveguide Grating (AWG) couples respective wavelength channels between a trunk fibre of the WDM-PON and a plurality of branch fibers of the WDM-PON. The AWG has a predetermined free spectral range and implements a channel plan comprising at least three spectral segments, each segment having a width equal to the free spectral range of the AWG. An Optical Line Terminal of the WDM-PON receives wavelength division multiplexed uplink signals within a first one of the spectral segments, and transmits wavelength division multiplexed downlink signals within a second one of the spectral segments. Respective channel plans within the first and second spectral segments are identical. An RF / Video broadcast transmitter generates an RF / Video broadcast signal within a third one of the spectral segments.

The invention discloses a fiber fault location equipment, method and device in the optical receiving network field. The optical time-domain echo wave length selecting module of the equipment comprises the following parts: an optical switch and an array waveguide raster. The method comprises the following steps: detecting the fault of the turn-up channel by the fiber fault location equipment; informing the optical line ending equipment corresponding with the upgoing channel to break the sending of the downgoing data; producing the line diagnostic signal; proceeding with the downgoing sending of the light source modulating the optical line ending equipment; receiving selectively and analyzing the reflected line diagnostic signal by the fiber fault location equipment; reporting the concrete position of the fiber fault to the network administrator according to the analyzed result. The device comprises the following parts: a control module, a modulating module, a sending module and a fiber fault position module. The invention reduces the cost of the fiber fault position system.

An optical equalizer / dispersion compensator (E / CDC) comprises an input / output for receiving a multiplexed channel signal comprising a plurality of channel signals of different wavelengths. An optical amplifier may be coupled to receive, as an input / output, the multiplexed channel signals which amplifier may be a semiconductor optical amplifier (SOA) or a gain clamped-semiconductor optical amplifier (GC-SOA). A variable optical attenuator (VOA) is coupled to the optical amplifier and a chromatic dispersion compensator (CDC) is coupled to the variable optical attenuator. A mirror or Faraday rotator mirror (FRM) is coupled to the chromatic dispersion compensator to reflect the multiplexed channel signal back through optical components comprising the chromatic dispersion compensator, the variable optical attenuator and the optical amplifier so that the multiplexed channel signal is corrected partially for equalization and chromatic dispersion compensation with respect to each pass through these optical components. The E / CDC components may be integrated in a photonic integrated circuit (PIC) chip. In several embodiments, a photonic integrated circuit (PIC) chip comprises an input into the chip that receives at least one channel signal having experienced chromatic dispersion, a chromatic dispersion compensator (CDC) that separates the at least one channel signal into separate wavelength components over a free spectral range (FSR) spanning only a signal channel width and subjects the wavelength components to a phase shift to change the wavelength group delay in the wavelength components and that recombines the wavelength components to reconstitute the at least one channel signal, and an output from the chip for the recombined at least one channel signal having reduced chromatic dispersion compared to the same channel signal received at the chip input. The CDC device may include a tuning section to vary the phase shift of wavelength components as they propagate through the device. Such a CDC device may include a Mach-Zehnder interferometer (MZI) or a cascaded group of Mach-Zehnder interferometers, or at least one arrayed waveguide grating (AWG) or at least one Echelle grating.

An optical fiber amplifier utilizing a phosphate glass optical fiber highly doped with rare-earth ions such as erbium to exhibit high gain per unit length, enabling the use of short fiber strands to achieve the needed gain in practical fiber optical communication networks. The high-gain phosphate optical glass fiber amplifiers are integrated onto substrates to form an integrated optics amplifier module. An optical pump such as a semiconductor laser of suitable wavelength is used to promote gain inversion of erbium ions and ultimately provide power amplification of a given input signal. Gain inversion is enhanced in the erbium doped phosphate glass fiber by co-doping with ytterbium. A phosphate fiber amplifier or an integrated optics amplifier module utilizing this power amplification can be combined with other components such as splitters, combiners, modulators, or arrayed waveguide gratings to form lossless or amplified components that do not suffer from insertion loss when added to an optical network. The fiber amplifier can be a single fiber or an array of fibers. Further, the phosphate glass fibers can be designed with a temperature coefficient of refractive index close to zero enabling proper mode performance as ambient temperatures or induced heating changes the temperature of the phosphate glass fiber. Large core 50-100 .mu.m fibers can be used for fiber amplifiers. The phosphate glass composition includes erbium concentrations of at least 1.5 weight percentage, preferably further including ytterbium at 1.5 weight percentage, or greater.

The invention discloses a microwave signal optical fiber stationary phase transmission system based on a microwave phase shifter. The system comprises a central station, a far end and a single-mode optical fiber. The central station is connected with the far end through the single-mode optical fiber. The central station is composed of a semiconductor laser device, a dual-drive Mach-Zehnder modulator, a microwave signal source, a first power divider, a first optical filter, an erbium-doped optical fiber amplifier, an optical coupler, a first array waveguide grating, a first photoelectric detector, a frequency eliminator, a second power divider, an optical source, a strength modulator, a second optical filter, an optical circulator, a second photoelectric detector, a first electric mixer, a band-pass filter, a second electric mixer, a low-pass filter and a linear voltage amplification circuit. The far end is composed of a second array waveguide grating, a third photoelectric detector and a Faraday polariscope. According to the invention, the advantage of low building and maintenance cost can be realized; and the phase jitter of microwave signals can be extracted and fed back on a real-time basis.

A mode-locked laser that has an optical cavity containing multiple optical amplifiers, each dedicated to a respective spectral portion of an optical signal generated by the laser, wherein the dispersion effects are managed by utilizing a separate intra-cavity phase tuner for each such spectral portion and / or by having appropriately configured waveguides corresponding to different spectral portions. Advantageously, a relatively wide combined gain spectrum provided by the optical amplifiers and the intra-cavity dispersion compensation provided by the phase tuners and / or waveguides enable this laser to realize a mode-locking regime that results in the emission of an optical pulse train having a relatively wide frequency spectrum. In one embodiment, the optical cavity of the mode-locked laser has a perfectly spectrally sampled arrayed waveguide grating (AWG) that is configured to divide the optical signal into the spectral portions and apply these portions to the respective waveguides, optical amplifiers, and phase tuners.

A method of depositing a top clad layer for an optical waveguide of a planar lightwave circuit. A GeBPSG top clad layer for an optical waveguide structure of a planar lightwave circuit is fabricated such that the top clad layer comprises doped silica glass, wherein the dopant includes Ge (Germanium), P (Phosphorus), and B (Boron). In depositing a top clad layer for the optical waveguide, three separate doping gasses (e.g., GeH4, PH3, and B2H6) are added during the PECVD (plasma enhanced chemical vapor deposition) process to make Ge, P and B doped silica glass (GeBPSG). The ratio of the Ge, P, and B dopants is configured to reduce the formation of crystallization areas within the top clad layer and maintain a constant refractive index within the top clad layer across an anneal temperature range. A thermal anneal process for the top clad layer can be a temperature within a range of 950C to 1050C. The GeBPSG top clad layer reduces the insertion loss of passive arrayed waveguide grating devices and active planar lightwave circuit devices.

The invention discloses a passive optical network (PON) and a signal transmission method thereof. The PON comprises a wavelength selection coupler, an optical splitter, an array waveguide grating (AWG) and a plurality of wavelength selection routers, wherein, the wavelength selection routers couple a downlink signal from a time division multiplexing optical line terminal (TDM-OLT) of the optical splitter and a downlink signal from a wavelength division multiplexing optical line terminal (WDM-OLT) of the AWG and then transmit the coupled signals to branch optical fibers connected with the wavelength selection routers, and transmit an uplink signal in a branch optical fiber connected with a WDM optical network unit (WDM-ONU ) to the AWG and then transmit an uplink signal in a branch optical fiber connected with a TDM-ONU to the optical splitter. The invention enhances network compatibility and improves user experiences.

An arrayed waveguide grating may include a plurality of waveguides, each associated with a different channel in a wavelength division multiplexed system. Each incoming signal channel in a node of a wavelength division multiplexed network may be of an arbitrary wavelength and is provided to one of the wavelength converters attached on the arrayed waveguide grating. Each converter also receives one of blank light channels of different wavelengths on a grid. The converters convert each of the incoming wavelength signals to one of the distinct new wavelength signals on the grid of wavelengths, and these new wavelength signals are multiplexed into a fiber.

An improved cantilever beam optical switch methodology which provides the function of a variable optical attenuator (VOA). A small degree of intentional misalignment of the waveguide will create different levels of optical attenuation. By finely controlling the misalignment of a selected switched position, a single device may be realized that will provide the functions of both switching and attenuating or just attenuation alone. The optical MEMS device utilizes a latching mechanism in association with a thermal drive actuator for aligning a cantilever beam platform. The integration of the switching function and the VOA function reduce the optical loss which is otherwise unavoidable when the inevitable alterative of a separate switch and a separate VOA must necessarily be employed. The resultant improved device can also be applied for correcting the difference in optical intensity created by the manufacturing tolerances inherent in the fabrication of array waveguide gratings.

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).

An arrayed waveguide grating type optical multiplexer and demultiplexer which reduces a package size although plural arrayed waveguide gratings are included, is provided, comprising plural arrayed waveguide gratings which are provided in parallel to one another on a substrate and each of which has a first waveguide, a first slab waveguide, an arrayed waveguide, a second slab waveguide, and a second waveguide, and also includes a waveguide chip divided into a first and second separated waveguide chip in the first or second slab waveguide in each of the arrayed waveguide gratings and a compensation member compensating a temperature dependent shift of a light transmission center wavelength in the arrayed waveguide grating by relatively moving the first and second waveguide chip when expanded or contracted according to a temperature change. The waveguide chip has a shape bending along a bending direction of the arrayed waveguide.

A scanning optical spectrometer with a detector array is disclosed, in which position of focused spot of light at the input of a dispersive element such as arrayed waveguide grating (AWG) with a slab input, is scanned using a micro-electro-mechanical (MEMS) tiltable micromirror so as to make the dispersed spectrum of light scan over the detector array coupled to the AWG. Sub-spectra recorded using individual detectors are concatenated by a processor unit to obtain the spectrum of input light.

An arrayed waveguide grating router (AWGR) comprises sets of output waveguides for a number of bands. Angular separation of adjacent output waveguides is relatively small for adjacent output waveguides. within a band and significantly larger for adjacent output waveguides belonging to different bands. In specific embodiments the output waveguides are arranged into at least two bands, each band comprising at least two adjacent waveguides. Each band is used in conjunction with an input waveguide specific to the particular band. AWGRs according to the invention may be made so that the passbands from a plurality of output waveguides fall on a wavelength grid or a frequency grid. Dummy waveguides may be included for ease of fabrication.

The present invention discloses a concept of natural index contrast (NIC) for producing photonic waveguides and methods of fabrication thereof. Such waveguide forms the basis of a class of chip-scale micro- and nano-photonic integrated circuits (PICs). The NIC method utilizes the built-in refractive index difference between two layers of dielectric thin films of two different materials, one laid on top of another. This new class of waveguides simplifies the PIC fabrication process significantly. Based on the NIC based waveguides, PICs can be fabricated for a number of photonic applications such as arrayed waveguide grating (AWG), reflective arrayed waveguide grating (RAWG), interleaver, interferometer, and optical sensor. Additionally, several other PICs can also be fabricated via tiers of integration, such as triple-phase integration. Examples of such devices include optical amplifier, wavelength router, sensor, optical modulator, transmitter, receiver, transponder, fully built dense wavelength division multiplexer and demultiplxer, optical power splitter, multicahnnel tunable optical attenuator, and multicahnnel tunable optical add-drop multiplexer. Unlike hybrid integration, triple-phase integration monolithically integrates multiple optical functionalities on a single chip.