133 results about "Wavelength reuse" patented technology

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.

In an optical device, each of a plurality of radiation sources generates a separate different wavelength output signal to a wavelength locking device wherein a grating device receives the separate wavelength output signals from the plurality of radiation sources. The grating device generates a multiplexed wavelength output signal at a zero diffraction order output port thereof, and resolves separate symmetric wavelength−δ and wavelength−δ output signals at separate predetermined locations within at least one non-zero diffraction order thereof for each of the radiation sources. Each of a plurality of radiation detectors is coupled to receive a separate one of the symmetric wavelength−δ and wavelength−δ output signals and generate an output signal representing the magnitude of the received wavelength output signal. A control device is responsive to output signals from each pair of radiation detectors coupled to receive the separate symmetric wavelength+δ and wavelength−δ output signals from a specified predetermined radiation source for generating an output control signal appropriate to that radiation source for locking the wavelength thereof.

The invention relates to a system for realizing wavelength reuse of a self-injection wavelength division multiplexing passive optical network and a method thereof. The system is formed by an optical line terminal OLT connected with remote nodes RN through a feed fiber, and the remote nodes RN connected with a plurality of optical network units ONU, wherein 2n optical network units ONU are divided into a group I of the optical network units ONU and a group II of optical network units ONU, and the number of the optical network units ONU in each group is the same, while uplink signals and downlink signals of two groups of the optical network units ONU are just opposite and do not have interaction with each other; the remote nodes are connected with the two groups of the optical network units ONU respectively and realize downlink signal separation, uplink signal combination and generation and return of seed light of the two groups of the optical network units ONU. The method realizes wavelength reuse by the system, divides the usable wave band into a wave band A and a wave band B, wherein the group I of the optical network units ONU carries the uplink signal and the seed light thereof by the wavelength of the wave band A, carries the downlink signal by the wavelength of the wave band B, while the group II of the optical network units ONU are just the opposite, thereby reusing the uplink signal and the downlink signal of the group I of the optical network units ONU by the group II of the optical network units ONU, not only avoiding that the seed light and the downlink signal cannot be separated by the optical network units ONU due to the fact that the seed light and the downlink signal are in the same wave band and are aliased with each other, but also realizing doubling of the number of the optical units ONU supported by the system and the wavelength utilization ratio.

A differential interference contrast (DIC) microscope system is provided comprising: (a) an illumination source for illuminating a sample ; (b) a lens system for viewing the illuminated sample, including an objective, defining an optical axis; (c) at least one detector system for receiving a sample image; (d) mechanisms for wavelength multiplexing the shear direction or shear magnitude or both on the sample and demultiplexing the resultant DIC images on the detector; and (e) a mechanism for modulating the phase of the interference image. Various approaches are disclosed to accomplish wavelength multiplexing of shear direction and demultiplexing the two DIC images that result. It is possible for the two, wavelength multiplexed DIC images to differ in either or both shear direction or magnitude. These approaches include (1) two DIC microscopes, each operating at a different wavelength, but which share a single objective through a beam splitter; (2) a segmented DIC prism that is made in four sections where opposite sections are paired and have the same shear direction and amount, and each pair of sections have filters transmitting different wavelengths; (3) a segmented DIC prism that is located in or near an aperture stop or pupil of said DIC microscope to obtain data in two shear directions that is multiplexed by wavelength; (4) a dual field-of-view optical system with two DIC prisms, one in each path to wavelength multiplex shear direction or shear magnitude through said objective; (5) demultiplexing wavelength multiplexed DIC images through the use of a wavelength selective beam splitter and two detectors; (6) demultiplexing wavelength multiplexed DIC images through the use of a wavelength controlled source and a single detector; and (7) demultiplexing wavelength multiplexed DIC images through the use of dual field-of-view optics and a single detector. These various approaches permit rapid, robust measurement of slope in two directions. Further, phase shifting and DIC microscopy are limited to measurements within the depth of focus (DOF) of the objective while WLI microscopy is not.

A wavelength-multiplexing optical transmission system includes (a) an optical transmitter 100 for wavelength-multiplexing a plurality of optical signals having different wavelengths and transmitting a wavelength-multiplexed optical signal, (b) an optical fiber cable 4 for transmitting a plurality of transmitted optical signals, and (c) an optical receiver 101 for receiving a plurality of transmitted optical signals. The optical receiver 101 includes a wavelength selector 20 for demultiplexing an optical signal having a predetermined wavelength of a plurality of received optical signals and outputting the demodulated signal. The wavelength selector 20 has comb-shaped wavelength selection characteristics for selectively filtering an optical signal having a plurality of selected wavelengths. A wavelength selection interval DELTA lambda between two adjacent selected wavelengths of the wavelength selection characteristics is different from a signal wavelength interval delta lambda between two adjacent signal wavelengths of a plurality of wavelength-multiplexed optical signals. The difference therebetween is set so that substantially a single optical signal is selectively filtered from a plurality of received optical signals. The wavelength selector 20 includes a wavelength control mechanism 10 for shifting the selected wavelengths of the wavelength selection characteristics, respectively.

The invention provides a wavelength multiplexer / demultiplexer and a method of manufacturing the same. The present invention provides a wavelength multiplexer / demultiplexer comprising a Mach-Zehnder interferometer and an arrayed waveguide diffraction grating, the wavelength multiplexer / demultiplexer having a simple configuration and being capable of reducing the degradation in the temperature compensation characteristics of a temperature compensation material provided in the Mach-Zehnder interferometer or the peeling-off of the temperature compensation material, and a method of manufacturing the same. A wavelength multiplexer / demultiplexer comprises an AWG including two separated slab waveguides and an MZI including two arm waveguides. A temperature compensation groove is formed in the two arm waveguides, wherein in a space between the temperature compensation groove, and two separated slab waveguides, a compensation material, the refractive index matching that of the AWG or Mach-Zehnder interferometer, the compensation material having a temperature dependence coefficient with a sign different from that of the temperature dependence coefficient of the waveguide core and having plasticity or fluidity, is filled.

The present invention relates to a wavelength-multiplexed light amplifying apparatus to be used in a state of being connected to a branching portion of a multiplexing / branching unit or to be used for a mxn matrix optical switch of an optical cross-connect. The wavelength-multiplexed light amplifying apparatus is composed of a plurality of wavelength-multiplexed light amplifying units and an optical feedback loop system. A signal input port of an optical branching section in one wavelength-multiplexed light amplifying unit is connected to an output side of an optical amplifying section in the preceding wavelength-multiplexed light amplifying unit. This configuration disperses the power loss of an optical signal to perform amplification with high efficiency and further enables the expansion of the branching port in the in-service. Additionally, it can eliminate the need for the installation of an optical isolator or reduce the required value of isolation to stabilize the system, or can accomplish the control to maintain the gains of all ports constant.

A method and apparatus for implementing an RF photonic transversal filter that utilizes tap apodization and wavelength reuse to obtain a high side lobe suppression together with narrow and configurable passbands. Several taps are obtained from one wavelength by using dispersive optical delay lines such as chirped fiber gratings that introduce a delay between successive wavelengths. A selected subset of the input wavelengths is utilized to generate multiple taps per wavelength. Some of the taps are apodized to generate various filter transfer functions that yield a high side lobe suppression ratio.

A porous silicon filter for wavelength multiplexing and de-multiplexing. Preferred embodiments include rugate-type porous silicon filters with pores having continuously varying widths with pore depth an optical cross connect switch. In other preferred embodiments, the pores are filled with a material that changes index of refraction with changes in applied voltage, current or temperature. Important applications of these porous silicon filters are for multiplexing and de-multiplexing in fiber optic communication systems. For example, a preferred embodiment is an all optical fiber optic switch utilizing these filters.

Provided is a passive optical network (PON) based on a reflective semiconductor optical amplifier (RSOA). In the PON, seed-light-injection RSOAs are used in an optical line terminal (OLT) to achieve the color-less management of the wavelengths of OLT optic sources, and wavelength reuse RSOAs are used to achieve the color-less management of the wavelengths of ONTs. Therefore, problems related to ONT wavelength management can be eliminated by the wavelength reuse RSOAs, and problems related to OLT wavelength management can be eliminated by the seed-light-injection RSOAs.