73results about How to "Compensation for dispersion" patented technology

A system, process and software arrangement are provided to compensate for a dispersion in at least one portion of an image. In particular, information associated with the portion of the image is obtained. The portion of the image can be associated with an interference signal that includes a first electromagnetic radiation received from a sample and a second electromagnetic radiation received from a reference. The dispersion in the at least one portion of the image can be compensated by controlling a phase of at least one spectral component of the interference signal.

A system (100) for transmitting digital information includes a transmitting apparatus (102) for generating an optical signal bearing digital information, a dispersive optical channel (104), and a receiving apparatus (110) for receiving the optical signal. The dispersive optical channel (104) is disposed to convey the optical signal from the transmitting apparatus (102) to the receiving apparatus (110). The transmitting apparatus includes an encoder (114) for encoding digital information into a series of blocks, each including a plurality of data symbols corresponding with one or more bits of digital information. A signal generator (118) generates a time-varying signal corresponding with each of said blocks. An optical transmitter (136) is arranged to apply the time-varying signal to an optical source (138) to produce an optical signal which includes an optical carrier and substantially only a single information bearing optical sideband in an optical frequency domain, the sideband corresponding with the time-varying signal. The receiving apparatus (110) includes an optical detector (146) for detecting the optical signal to produce a corresponding received time-varying electrical signal. The receiver further includes means (166) for generating a series of received data blocks from the time-varying electrical signal. An equaliser (168) performs an equalisation of received data symbols included in each data block to mitigate the effect of dispersion of the optical channel, thereby enabling the transmitted data symbols to be recovered.

An inverse dispersion fiber having a large effective area and a transmission system that incorporates the fiber for providing dispersion and dispersion slope compensation in a transmission fiber. The large-effective-area inverse dispersion optical fiber (IDF) has a negative dispersion and a negative dispersion slope. The effective area, A_eff, of the IDF preferably is greater than approximately 31 micrometers squared (μm²) at a transmission wavelength of approximately 1550 nm. The large-effective-area IDF is suitable for use with super-large-effective-area (SLA) transmission fiber for compensating dispersion in the SLA transmission fiber while reducing nonlinear effects between wavelength channels and cabling loss, which is especially advantageous in transoceanic and long-haul terrestrial systems. These nonlinear effects are inversely related to the effective area of the fiber (i.e., nonlinearities˜1/A_eff). Thus, an increase in the effective area of the fiber translates into a decrease in nonlinear interactions, which increases bandwidth capabilities and limits signal degradation. Furthermore, the large-effective-area IDF of the present invention has very desirable transmission properties. The present invention also provides a transmission system comprising at least one of the large-effective-area IDF optical fibers of the present invention. Furthermore, A_eff can be made large without having to increase the ratio, R_a, of the diameter of the core to the diameter of the trench region.

The problem of the invention is to so develop known dispensers, that it is possible to very precisely determine the actual discharged medium volume. A dispenser according to the invention has a media path, which leads from a medium storage container to a discharge opening. A delivery device for delivering medium is located in said media path. The media reservoir stores a medium, particularly a fluid, which preferably incorporates at least one pharmaceutical substance. A media discharge can be brought about by means of an operating means. According to the invention, on the dispenser is provided an electronic detecting device for detecting a quantity representing the amount of medium discharged.

A coherent optical receiver includes a 90-degree optical hybrid circuit to which a received signal light is input, I-channel and Q-channel photo detectors to which the outputs of the hybrid circuit are input, a clock extraction circuit which reproduces a clock whose speed is the same as a demodulated signal obtained by demodulating the received signal light and which is synchronized therewith, I-channel and Q-channel sampling circuits which sample the signal outputs from the I-channel and Q-channel photo detectors by use of the clock, and a digital signal processing section which digitally processes the sampled signals, converts them to a digital signal, and outputs the digital signal. The digital signal processing section feeds a phase offset signal detected there back to the clock extraction circuit to thereby control the phase of the clock, and compensates dispersion of light within a fiber and phase fluctuation during free-space propagation.

A planar dispersion compensator for an optical signal is provided. The compensator decomposes an inputted optical signal into N component signals separated by a fractional wavelength deltalambda. Each component signal has its path-length adjusted to induce a sufficient phase shift between input and output to change the group delay of the optical signal when recombined from each of the component signals. In this manner, pulse broadening can be compensated by selectively varying the induced phase shifts to produce the desired level of opposite group delay.

From an real valued OFDM signal (S₀(t)) is a baseband signal (S_B(t)) derived and converted into a complex single sideband modulation signal (n(t)). This is modulated onto an optical carrier (f_OC) to generate a SSB transmission signal (S_OT) having a small bandwidth an carrying the information in the envelope or in the power of the envelope. According to the modulation direct detection is possible. Only a small bandwidth is necessary for the transmission.

The invention describes a transmission component for producing chromatic dispersion which can be predetermined, having

• • a glass fiber optical waveguide in which it is possible to carry not only the LP₀₁ fundamental mode but also at least one LP_mn mode, and
  • two pairs of Bragg gratings (gratings 1 and 2, as well as 3 and 4), of which at least one pair has chirped Bragg gratings,

in which the first Bragg grating in each pair reflects the arriving light beam back to the other Bragg grating in a direction approximately opposite the incidence direction, and from which other Bragg grating the light beam emerges in, or at least parallel to, the original incidence direction.

A method and apparatus are disclosed for replacing riveted metal components in place on existing metal structures. The method includes the steps of positioning a rivet removing tool at a rivet on an in situ structural component that is maintained in place by a plurality of rivets, encoding the position of the rivet removing tool at the rivet and transmitting the encoded position of the rivet to a processor, removing the rivet, sequentially moving the rivet removing tool to each of the rivets on the structural component that hold the structural component in place, sequentially encoding the position of the rivet removing tool at each rivet, transmitting the encoded the position of each rivet to the processor, and removing each rivet with the tool when the tool is at the rivet, designing a replacement component based upon the encoded positions of the rivets and fabricating the replacement component based on the transmitted rivet positions.

A dispersion compensation device for compensating chromatic dispersion of optical pulses launched from the exterior is disclosed. The device comprises a waveguide and a photonic crystal part, the waveguide comprising a core part for guiding the optical pulse from an input end to an output end and a clad part consisting of a first clad layer and a second clad layer, the photonic crystal part providing a chromatic dispersion variation of a proper dispersion characteristic to the optical pulses guided through the waveguide, the chromatic dispersion variation having an absolute value of the variation and a positive or negative sign, wherein the photonic crystal part is layered onto the first clad layer, the core part is layered onto the photonic crystal part, and the second clad part is formed so that a portion of which is layered onto the photonic crystal part and a remaining part of which covers the exposed surface of the core part.

The present invention provides a dispersion compensator applicable to a WDM optical transmission system and featuring low loss, wideband usage, and minimum ripple. The dispersion compensator is constructed so that the light emitted from a collimator will be reflected from an etalon of a 100% single-side reflectance by arranging the etalon and a mirror in parallel or with a slight angle and then enter another collimator. Elements for achieving variable dispersion compensation by changing temperature using a heater, for example, are also provided. In addition, these dispersion compensating elements are provided in multi-stage form and the angle of the mirror and the reflectance of the etalon are optimized. Thus, it becomes possible to realize a dispersion compensator applicable to a WDM optical transmission system and featuring low loss, wideband usage, and minimum ripple.

Described are an optical communications system and a method that allow for compensation of chromatic dispersion and polarization mode dispersion imparted to a communications signal propagating through an optical link. The system is based on a cost-effective optical transport architecture that accommodates baud rates exceeding 15 Gbaud and eliminates the need for costly optical dispersion compensators. Compensation for polarization mode dispersion is performed at the receiver using nonlinear processing. Advantageously, direct detection modulation using inexpensive electro-optic system components can be used in place of more costly and complex coherent and differential modulation formats. Digital filtering can be performed at the transmitter and the input signal can be inverted based on the nonlinearity of the transmitter electro-optic components. Consequently, the bandwidth and linearity requirements for the transmitter electro-optic components are relaxed, and cost reductions are realized.

A reconfigurable wavelength selective dispersion compensation device RWSDCD for selective compensation of dispersion in optical channels having different wavelengths. The RWSDCD comprises a controllable wavelength selective unit WSU having a plurality of local, wavelength related input/output (I/O) ports. The RWDSD also comprises a dispersion compensation cascade comprising at least one chain of successively connected dispersion compensation units DCUs, wherein one or more of the DCUs in the chain are respectively connectable to one or more of the local I/O ports. The RWSDCD outputs one or more of the incoming optical channels upon selectively compensating chromatic dispersion in them, by controllably passing these channels via one or more DCUs of the dispersion compensation cascade.

A method of determining an optical distance between two nodes of an optical network for chromatic dispersion compensation includes using existing optical supervisory channel components in each node to measure the “time-of-flight” of an optical signal having a known wavelength. The effective optical distance is determined based on the time-of-flight and known wavelength of the optical signal. The computed optical distance may then be used to compensate for the dispersion experienced by the optical signal when transmitted between the two nodes. Advantageously, the method allows tunable dispersion compensation of a wavelength channel to be periodically optimized at each node in response to incremental changes in environmental factors that affect the chromatic dispersion produced between the two nodes or in response to reconfigurations that affect the chromatic dispersion produced between the two nodes.

A quantum nanostructure semiconductor laser is provided that does not use a buried structure defined by etching and regrowth processes in the prior arts, and can be manufactured using a procedure that is simple and has good reproducibility. This helps to reduce the threshold current and provides good lasing wavelength stability. The laser has a stripe-shaped ridge with a plurality of V-grooves formed on a compound semiconductor substrate in the direction of laser beam emisson, with the V-grooves being arrayed in parallel, with each V-groove extending orthogonally to the direction of laser beam emission. On the ridge, an optical waveguide is provided that comprises a lower cladding layer, a plurality of quantum wires and an upper cladding layer formed in order by a crystal growth process. The quantum wires are formed to a finite length corresponding to the stripe width of the laser beam, and are each located at a position corresponding to a V-groove, thereby constituting the laser active region. The optical waveguide is trapezoidal in shape, and has a peripheral sidewall that is at least as high as a height at which the quantum wires are located, and is exposed or covered only by an insulation layer.

A resonator-type variable dispersion compensator is provided which is effective for practical use with a wavelength division multiplex transmission system. The dispersion compensator is constructed so as to shift a variable range to the plus or minus side according to the particular specifications of a transmission line. The dispersion compensator with an etalon and a mirror arranged in parallel or at a slight angle with respect to each other is constructed so that emitted light from a collimator is reflected by the etalon multiple times and then enters another collimator. The dispersion compensator also has dispersion compensating units that change temperature using a heater or equivalent in order to render the amount of dispersion variable. In addition, these dispersion compensating units are provided in multi-stage form, and the angle of the mirror, the amplitude reflectance of the etalon, and temperature are optimized to offer polygonal dispersion characteristics. This realizes a practical, variable dispersion compensator suitable for a wavelength division multiplex optical transmission system and capable of shifting a variable amount of dispersion to the plus or minus side.

This invention discloses a backmixing non-conjugated grating pair Martinez impulse stretcher and compressor applied in the compensation impulse enlarger material with low color dispersion, which belongs to the structure technique of stretcher and compressor in the femtosecond enlarge system. The said Martinez stretcher comprises concave spherical reflecting lens, plane reflecting lens and grating. The said compressor comprises plane reflecting lens, inner right angle reflecting lens and grating, which is characterized by the following: the grating fringe density of the stretcher is larger than that of the compressor. The advantages of this invention are the following: backmixing non-conjugated grating pair Martinez impulse stretcher and compressor are applied in the multiple-pass enlarger with material of low dispersion and can effectively compensate the material dispersion in the enlarger and reduces the deformation of femtosecond impulse.

A control system for use in compensating for temperature-induced dispersion drift of an optical path, comprising an input adapted to obtain temperature data associated with the optical path; a control module adapted to determine control information on the basis of the temperature data; and an output adapted to provide a control signal to a dispersion compensator. The control signal is determined such that its receipt by the dispersion compensator causes the latter to induce a dispersive effect in a signal that travels the optical path, the dispersive effect being related to the control information. The ability to compensate for temperature-induced dispersion drift reduces the distortion margin in optical link budgets, allowing optical links to have longer reach, or to achieve the same reach using fewer line amplifiers. In a specific embodiment, dispersion compensation is accomplished via an open-loop control system such that feedback from the receiver site is not required.

The invention discloses a two-port tunable thin film filter (TFF) optical filter. The filter comprises a tunable optical filter unit, a wavelength detection unit and a control unit, wherein the tunable optical filter unit partially feeds input signal light back to the wavelength detection unit; the wavelength detection unit is connected with the tunable optical filter unit, detects the power change condition of the received signal light and outputs the condition to the control unit; and the control unit is connected with the wavelength detection unit, determines the drift condition of the central wavelength of output light through the power change condition of the output light of the wavelength detection unit, and corrects a tuning controller connected with the control unit. The filter has a simple structure and a built-in wavelength feedback structure and can completely eliminate influence caused by unstable light source power; symmetrical optical paths are adopted, so that all wavelengths and incident angles can completely compensate polarization mode dispersion caused by an optical path difference; the tuning performance of a device is improved; and the filter has the function of optical signal monitoring modules such as the Optical Society of America (OSA), an optical wavelength manager (OWM) and the like.