981 results about "Tunable laser" patented technology

Implementations described herein provide a method for processing a substrate on a substrate support assembly which enables both lateral and azimuthal tuning of the heat transfer between an electrostatic chuck and a substrate. The method includes processing a first substrate using a first temperature profile on the ESC having primary heaters and spatially tunable heaters. A deviation profile is determined from a result of processing the first substrate from a target result profile. The first temperature profile is adjusted to a second temperature profile on the ESC based on the deviation profile. Adjusting to the second temperature profile includes incrementing the power to one or more spatially tunable heaters in one or more discrete locations corresponding to the deviations profile. A second substrate is then processed on the ESC using the second temperature profile.

A gain medium 12 and a tunable filter are provided in an optical path of laser oscillation. The tunable filter has an optical beam deflector for periodically changing an optical beam at a constant angular speed, a prism 26 on which deflected light is made incident, and a diffraction grating 27. Appropriate selection of the apex angle α of the prism 26 and an angle β formed by the prism 26 and the diffraction grating 27 can provide a tunable laser light source for changing the oscillation frequency at high speed and a constant variation rate.

A microwave tunable filter having some advantages as follows: a) the integration of MEMS tunable filter and MMIC; b) the very low signal transmission loss and low dispersion; and c) the drastic variation and linear characteristic of frequency by means of MEMS capacitor and an external control signal. The microwave tunable MEMS filter includes a plurality of unit resonant cells, each unit resonant cell being formed by various serial and parallel combination of an inductor, a capacitor, a transmission line, and a variable MEMS capacitor, whereby capacitance variation of the variable MEMS capacitor in the unit resonant cell converts a resonant frequency of the unit resonant cell to thereby convert a center frequency of the filter.

A wavelength discretely tunable semiconductor laser that addresses wide wavelength tuning range, is mode hopping free, has high output power, has fast wavelength switching time, is wavelength locking free and is relatively simple. Four exemplary embodiments disclosed herein utilize a wavelength discretely tunable semiconductor laser that comprises a discretely tunable filter and laser amplifier. In the first embodiment, the tuning element comprises a pair of cascade Fabry-Perot filters, each having a plurality of characteristic narrow transmission passbands that pass only the cavity mode under the passband. The spacing between the narrow transmission passbands are slightly different in one filter from the other filter so that only one passband from each filter can be overlapped in any given condition over the entire active element gain spectral range, thereby permitting lasing only at a single cavity mode passed by the cascade double filters. One of the two etalon filters can be made with a plurality of transmission passbands predetermined by industry, application and international standards, making this element an intra-cavity wavelength reference and eliminating further wavelength locking needs for the tunable laser. In a second embodiment, one of the two etalons is replaced by a wedge filter. The filter optical path change and thus the transmission passband shift are achieved by translating the wedge filter in a direction perpendicular to the optical axis. In a third embodiment, one of the two etalon filters is replaced by a polarization interference filter. The polarization interference filter consists of an electro-optically-tunable birefringent waveplate, a fixed birefringent waveplate, the laser cavity and T.E. polarization light emitted from the laser diode. In a fourth embodiment, the laser and wavelength tuning structure are integrated on a semiconductor substrate by epitaxy processes.

A free-space communication transceiver includes a telescope for transmitting and receiving laser beams, a tunable laser transmitter for generating a transmit laser beam modulated with data, a tunable optical receiver for processing a receive laser beam received from the telescope to recover data, and a tunable beamsplitter that directs the transmit laser beam to the telescope and directs the receive laser beam from the telescope to the optical receiver. Between the telescope and beamsplitter, the transmit and receive laser beams travel along a common optical axis as collinear collimated free-space beams. The transmit and receive laser beams operate at different wavelengths that can be interchanged, thereby support full-duplex operation. The beamsplitter employs a tunable etalon filter whose wavelength-dependent transmission characteristics are adjusted according to the transmit and receive wavelengths. Optionally, RF signals can additionally be couple to the common optical axis and transmitted and received by the telescope.

A tunable laser for providing a laser beam with a selectable wavelength. In one example, the tunable laser includes a gain medium for generating the laser beam; a waveguide for processing the laser beam, the waveguide having liquid crystal material or other electro-optic material disposed therein; an optical path length control element disposed within said waveguide for controlling an effective optical path length of the laser cavity; and a wavelength selective element for controlling the wavelength of the laser beam. The tunable laser may be designed without any moving mechanical parts if desired.

Semi-integrated external cavity diode laser (ECDL) designs including integrated structures comprising a gain section, phase control section, and optional modulator section. Each integrated structure includes a waveguide that passes through each of the sections. A mirror is defined in the structure to define one end of a laser cavity. A reflective element is disposed generally opposite a rear facet of the gain section, forming an external cavity therebetween. A tunable filter is disposed in the external cavity to effectuate tuning of the laser. During operation, a modulated drive signal is provided to the phase control section. This modulates an optical path length of the laser cavity, which produces an intensity (amplitude) modulation in the laser output. A detector is employed to produce a feedback signal indicative of the intensity modulation that is used for tuning the laser in accordance with a wavelength locking servo loop. Upon passing through the modulator section, an optical signal is modulated with data.

Agile frequency converter and method, IF-RF level exchange process, and notch filtering techniques. System noise and spurious levels generated by channel frequency conversion is reduced in applications requiring broadband combining of frequency converters to form multichannel composite signal. Converter employs two-stage frequency conversion process, with gain exchange system using variable pre-mixer gain and variable post-mixer attenuation to maintain constant RF output signal power level. For those few conversion frequencies where distortion component(s) cannot be filtered without degrading desired signal, IF-RF level exchange is optimized for meeting the carrier-to-distortion (C/D) ratio specifications at slight expense of noise level for that channel only, while still meeting aggregate combined carrier-to-noise (C/N) specification requirements. Optimal apportionment of level exchange for each channel depends on specific frequency rejection capability of spurious components and is matched to filtering capability and stored within non-volatile memory of a microcontroller used in the frequency converter.

Implementations described herein provide a substrate support assembly which enables both lateral and azimuthal tuning of the heat transfer between an electrostatic chuck and a heating assembly. The substrate support assembly comprises a body having a substrate support surface and a lower surface, one or more main resistive heaters disposed in the body, a plurality of spatially tunable heaters disposed in the body, and a spatially tunable heater controller coupled to the plurality of spatially tunable heaters, the spatially tunable heater controller configured to independently control an output one of the plurality of spatially tunable heaters relative to another of the plurality of spatially tunable heaters.

An electrically focus-tunable lens having a passive lens and a liquid crystal diffractive lens both sandwiched between a first transparent substrate with a first electrode applied to one surface and a second transparent substrate with a second electrode applied to one surface. The electrodes are operative to apply at least one voltage across the liquid crystal diffractive lens

Photonic integrated circuits on silicon are disclosed. By bonding a wafer of III-V material as an active region to silicon and removing the substrate, the lasers, amplifiers, modulators, and other devices can be processed using standard photolithographic techniques on the silicon substrate. The coupling between the silicon waveguide and the III-V gain region allows for integration of low threshold lasers, tunable lasers, and other photonic integrated circuits with Complimentary Metal Oxide Semiconductor (CMOS) integrated circuits.

Dry oxygen, dry air, or other gases such as ozone are hermetically sealed within the package of the external cavity laser or ASE swept source to avoid packaging-induced failure or PIF. PIF due to hydrocarbon breakdown at optical interfaces with high power densities is believed to occur at the SLED and/or SOA facets as well as the tunable Fabry-Perot reflector/filter elements and/or output fiber. Because the laser is an external cavity tunable laser and the configuration of the ASE swept sources, the power output can be low while the internal power at surfaces can be high leading to PIF at output powers much lower than the 50 mW.

Techniques for stabilizing a laser at a selectable frequency include splitting an output beam from an electrically adjustable laser into a first beam and a second beam. The second beam is transmitted through a modulator. Then the second beam is transmitted through a transient spectral hole burning material onto a detector. The laser is electronically adjusted in response to a detector output from the detector which senses the changes in the modulated second beam after it passes through the transient spectral hole burning material. Additions here to encompass the mode-locked case?

A device contains at least one wavelength-tunable multilayer interference reflector controlled by an applied voltage and at least one cavity. The stopband edge wavelength of the wavelength-tunable multilayer interference reflector is preferably electrooptically tuned using the quantum confined Stark effect in the vicinity of the cavity mode (or a composite cavity mode), resulting in a modulated transmittance of the multilayer interference reflector. A light-emitting medium is preferably introduced in the cavity or in one of the cavities permitting the optoelectronic device to work as an intensity-modulated light-emitting diode or diode laser by applying an injection current. The device preferably contains at least three electric contacts to apply forward or reverse bias and may operate as a vertical cavity surface emitting light-emitter or modulator or as an edge-emitting light emitter or modulator. Using a multilayer interference reflector containing tunable section allows also obtaining a wavelength-tunable laser or a wavelength-tunable resonant cavity photodetector in the case where the optical field profile in the active cavity or cavities is affected by the stopband wavelength shift. Adding additional modulator sections enables applications in semiconductor optical amplifiers, frequency converters or lock-in optical amplifiers.

A cable television transmitter includes a substrate including a silicon material, control electronics disposed in the substrate, and a gain medium coupled to the substrate. The gain medium includes a compound semiconductor material. The cable television transmitter also includes an optical modulator optically coupled to the gain medium and electrically coupled to the control electronics, a waveguide disposed in the substrate and optically coupled to the gain medium, a first wavelength selective element characterized by a first reflectance spectrum and disposed in the substrate, and a second wavelength selective element characterized by a second reflectance spectrum and disposed in the substrate. The cable television transmitter further includes an optical coupler disposed in the substrate and joining the first wavelength selective element, the second wavelength selective element, and the waveguide and an output mirror.

A tunable laser includes a substrate comprising a silicon material and a gain medium coupled to the substrate. The gain medium includes a compound semiconductor material. The tunable laser also includes an optical modulator optically coupled to the gain medium, a phase modulator optically coupled to the optical modulator, and a waveguide disposed in the substrate and optically coupled to the gain medium. The tunable laser further includes a first wavelength selective element characterized by a first reflectance spectrum and disposed in the substrate, a second wavelength selective element characterized by a second reflectance spectrum and disposed in the substrate, an optical coupler disposed in the substrate and joining the first wavelength selective element, the second wavelength selective element, and the waveguide, and an output mirror.

A wavelength locker for use with tunable optical devices, such as tunable lasers, detectors, or wavelength selection filters is described. The invention enables the determination of an optical wavelength or waveband position of a tunable device. Embodiments of the invention supply a reference wavelength which may be used to tune the tunable device to a specified wavelength or waveband. The invention enables the tunable device to be locked to a desired wavelength. The invention enables discrete and continuously tunable optical wavelength determination and locking across a waveband. Applications for the invention include utilization in optical networks. For instance, the invention may be utilized to reference, tune, and lock an incoming signal at the receiving end of an optical network link. In particular, the invention may be used in tunable laser sources, tunable detectors, or tunable optical signal filters as used in optical fiber communications and DWDM applications.

The present invention includes various novel systems and methods for dynamically modifying WDM transmission and receive steps (individually or in combination), including encoding client signals, mapping them to subchannels within or across ITU channels, modulating them onto subcarrier frequencies, and multiplexing them together for optical transmission. By dynamically modifying one or more of these processing steps over time (as well as encrypting underlying client signals), additional security is provided at the physical (optical) layer of an optical network, thereby greatly enhancing overall network security. Tunable lasers are employed to generate respective subcarrier frequencies, which represent subchannels of an ITU channel to which client signals are mapped. Client circuits are divided and combined with one another before being mapped to individual subchannels within and across ITU channels, thereby facilitating desired optical routing, switching, concatenation and protection of the client circuits mapped to those subchannels across the nodes of a WDM network.

According to various embodiments and aspects of the present invention, there is provided a dynamically tunable thin film interference coating including one or more layers with thermo-optically tunable refractive index. Tunable layers within thin film interference coatings enable a new family of thin film active devices for the filtering, control, modulation of light. Active thin film structures can be used directly or integrated into a variety of photonic subsystems to make tunable lasers, tunable add-drop filters for fiber optic telecommunications, tunable polarizers, tunable dispersion compensation filters, and many other devices.

The present disclosure provides reconfigurable optical add drop multiplexer (ROADM) node automatic topology discovery systems and methods providing a mapping of optical connections within a mesh optical network that includes tunable lasers and multi-degree ROADM's with colorless/directionless add/drop. The present disclosure may include additional transceiver, receiver, and add/drop filter equipment integrated in or disposed at a ROADM degree. This equipment supports a so-called topology wavelength which is one of a plurality of wavelengths supported by a wavelength division multiplexed (WDM) system that is dedicated and used solely for topology discovery. The topology wavelength may be utilized by the system to detect interconnects between ROADM degrees and between XCVRs/CDMDs. Further, the automated topology discovery may be integrated within a management system and/or control plane.

A monolithically-integrated semiconductor optical transmitter that can index tune to any transmission wavelength in a given range, wherein the range is larger than that achievable by the maximum refractive index tuning allowed by the semiconductor material itself (i.e. Δλ/λ>Δn/n). In practice, this tuning range is >15 nm. The transmitter includes a Mach-Zehnder (MZ) modulator monolithically integrated with a widely tunable laser and a semiconductor optical amplifier (SOA). By using an interferometric modulation, the transmitter can dynamically control the chirp in the resulting modulated signal over the wide tuning range of the laser.

A wavelength tunable laser comprises a multiple ring resonator, an input/output side waveguide coupled to a ring resonator, a reflection side waveguide coupled to a ring resonator, a multiple ring resonator, a PLC substrate where the input/output side waveguide and the reflection side waveguide are formed, a high reflection film set on the reflection side waveguide, a SOA connected to the input/output side waveguide through a anti-reflection film, a film heater which is placed above a ring waveguide for wavelength tuning in the PLC substrate and provides heat to the ring waveguide for wavelength tuning, and a adiabatic groove, which restrain conducting heat provided by the film heater to the PLC substrate except the ring waveguide for wavelength tuning.

An optical lasing device, comprising (i) a lasing medium disposed in a lasing cavity, (ii) an etalon disposed within the lasing cavity, and (iii) an electrically tuned filter device, such as a grating waveguide structure device. The lasing device also comprises a detector for determining the lasing power of the lasing device, and a controllable phase shift capability, and the device is preferably locked to a maximum of the lasing power by adjusting the phase, thereby achieving locking to a wavelength predetermined by the etalon, aligned to an ITU grid wavelength. Adjusting the phase shift to achieve the maximum of the lasing power is preferably performed using a closed loop system. Furthermore, adjusting of the phase shift to achieve a maximum of the lasing power is preferably also operative to wave lock the lasing device to a peak wavelength of the etalon.

The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate subcarrier frequencies representing subchannels of an ITU channel to which client signals can be mapped. Client circuits can be divided and combined before being mapped, independent of one another, to individual subchannels within and across ITU channels. Subchannels may be independently routed to a single subchannel receiver filter, such that each subchannel detected at the receiver may come from a different source location. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of client circuits mapped to these subchannels across the nodes of a WDM network. Subchannel hopping may also be used to increase the optical network security.

The present invention provides for an imaging system that obtains, as well as a method for obtaining, the colorimetric value of a plurality of points in a scene when the scene is lit by a source of illumination. The system comprises an imaging detector, imaging optics that receive light from the scene and direct it to the detector, a tunable filter responsive to applied electrical signals that filters the spectrum of light passing therethrough, and a control circuit for acquiring and storing a plurality of images from the detector while the tunable filter expresses a plurality of predetermined filter response functions in response to applied electrical signals, and for determining the colorimetric values from the stored images, wherein each of the filter response functions has substantial transmission at a plurality of wavelengths.

The method and system operate to calibrate a transmission laser of the dense wavelength division multiplexer (DWDM) and to lock the laser to a selected transmission wavelength. In one example, the transmission laser is a widely tunable laser (WTL) to be tuned to one of a set of International Telecommunications Union (ITU) transmission grid lines for transmission through an optic fiber. To lock the WTL to an ITU grid line, a portion of the output beam from the WTL is routed through the etalon to split the beam into a set of transmission lines for detection by an etalon fringe detector. Another portion of the beam is routed directly to a laser wavelength detector. A wavelength-locking controller compares signals from the two detectors and adjusts the temperature of the etalon to align the wavelength of one of the transmission lines of the etalon with the wavelength of the output beam, then controls the WTL in a feedback loop to lock the laser to the etalon line. The wavelength-locking controller thereafter monitors the temperature of the etalon and keeps the temperature constant to prevent any wavelength drift in the etalon. In one example, the optical components are aligned so that laser wavelength detector receives a portion of the laser beam directly from the laser so that phase characteristics of the laser beam are not affected by an intervening beamsplitter thereby permitting improved wavelength locking. In another embodiment, an etalon chirp filter is provided for reducing or eliminating optical frequency chirp, regardless of the particular ITU channel being used for transmission.

A tunable laser includes a substrate comprising a silicon material, a gain medium coupled to the substrate, wherein the gain medium includes a compound semiconductor material, and a waveguide disposed in the substrate and optically coupled to the gain medium. The tunable laser also includes a first wavelength selective element characterized by a first reflectance spectrum and disposed in the substrate and a carrier-based phase modulator optically coupled to the first wavelength selective element. The tunable laser further includes a second wavelength selective element characterized by a second reflectance spectrum and disposed in the substrate, an optical coupler disposed in the substrate and optically coupled to the first wavelength selective element, the second wavelength selective element, and the waveguide, and an output mirror.

A multi-line tunable laser system, which uses lasers as light sources to illuminate, identify and or quantify one or more targets based on multi-dimensional spectral characteristics of each target. The system includes a plurality of laser sources, each tunable to emit an electromagnetic wave, and at least one tuning controller for tuning and locking each beam of light to a wavelength of required spectral line-width. The system also includes a transmitter for transmitting each beam of light to illuminate one or more targets, and a receiver for receiving light returning from the targets and converting the returned light to electrical signals for identifying and or quantifying the targets. The system further includes N tunable lasers where, M of the N lasers are each tuned to a wavelength that is partially absorbed by the targets, and L of the N (one or more) of the lasers are each tuned to a wavelength that is absorption-free of the targets.

A surface emission laser light source is used as a tunable laser light source. Since the surface emission laser light source can realize a broad frequency scanning range at a high speed and in the single mode, a coherent length is longer than that of a multi mode light source. For this reason, when a tomography image is calculated by executing the Fourier transform for an output obtained from an interference optical device, measuring depth can be deepened.

A method of optimizing the operation point of a laser, including characterizing the laser and controlling the different laser sections by varying the currents injected into the respective laser sections. The method includes sensing discontinuities that occur at mode jumps in a signal by utilizing a detection device that is firmly connected to the laser. Control of the different laser sections is effected by means of a control unit. Different control current combinations and the signal delivered by the detection device are provided to the control unit, which causes the control unit to detect the mode plane of the laser. At least a part of a mode plane, or several mode planes, are stored in a memory connected with the control unit, and the control unit controls the different laser sections so that the laser will operate at the desired operation point.