Lucent Technologies Inc.

At&t Bell Laboratories

At+t Corp.

American Telephone & Telegraph Co., At&t Bell Laboratories

At&t Ipm Corp.

Multiplex, Inc.

Kang-Yih Liou

Uziel Koren

Bernard Glance

Christopher Richard Doerr

Won-Tien Tsang

Thomas L Koch

Robert D Feldman

Tawee Tanbun-Ek

Liang David Tzeng

Fumio Koyama

Martin G Young

An optical transponder/transceiver for intermediate range (e.g., 10-50 km) optical communication applications utilizes an electroabsorption modulated laser for the transmitting device. Preferably, the laser operations at a wavelength of approximately 1310 nm and comprises an electroabsorption modulated Fabry-Perot laser.

Optical transponders and transceivers

Data loss is reduced and bandwidth efficiency improved while tuning an optical add/drop device comprising a hitless wavelength-tunable optical filter. The hitless wavelength-tunable optical filter includes a broadband reflective surface and a tunable filter surface, the reflective surface and filter surface positioned adjacent to each other. Hitless tuning of the device is accomplished by changing the point at which an optical beam strikes the filter surface along a constant wavelength channel track whenever the beam is incident to the filter surface region. Realignment to a position associated with a new wavelength channel track is performed with the optical beam incident to the reflective surface region. Repositioning the optical beam to the filter region occurs at a location corresponding to the new wavelength to be added/dropped and subsequent optical beam realignment within the filter region is along the new wavelength channel track.

Tunable optical add/drop device and method

A stable single-mode wavelength selectable ring laser operates at a single wavelength which is selectable from any channel passband of a multiple-channel wavelength multiplex/demultiplexer element (e.g., an arrayed waveguide grating router (AWGR)). A Fabry-Perot semiconductor optical amplifier (FP-SOA) is connected together with the AWGR to form a ring laser structure where the FP-SOA is used as an intra-cavity narrow-band mode-selecting filter to stabilize ring laser oscillation to a single axial mode. This is the first time that a FP-SOA is used in a fiber ring laser as a mode-selecting interferometer with gain.

Wavelength-selectable fiber ring laser

An apparatus and method pulses a broadband optical source such as an LED, and generates multiple optical wavelength signals channels which are time division multiplexed onto a single optical channel. The multiple optical wavelength signals may subsequently be modulated by low frequency data signals and then transmitted to a receiver as corresponding multiple independent optical wavelength channels over a single optical fiber. Both spectral slicing and time division multiplexing are accomplished by a wavelength channel defining assembly including a wavelength grating router (WGR) and optical delay lines by using the periodic routing characteristics of the WGR. The WGR separates the broadband optical signal appearing at one input port of the WGR into discrete wavelength bands constituting respective pulses defining the optical wavelength channels by spectrally slicing the broadband optical source frequency spectrum with a multiple channel filter. The WGR then routes each of the wavelength signals to corresponding output ports. Optical delay lines then loop-back the separate wavelength signals from the output ports to other WGR input ports determined according to the routing characteristics of the WGR to multiplex the channels onto a single output port, while also inserting the delay to separate the wavelength signals in time.

WDM transmitter for optical networks using a loop-back spectrally sliced

A Wavelength Division Multiplexing (WDM) transceiver includes a Wavelength Multiplexer/Demultiplexer (WM/D) having a plurality of inputs (N) and N Amplified Light Emitting (ALED) devices, each ALED device transmitting a wideband optical signal to and receiving an optical signal from a different one of the N inputs of the WM/D transceiver. During transmission, the WM/D selects different wavelengths from ALED signals at each of the N inputs and multiplexes them together into a combined signal at its output. During receiving, the WM/D demultiplexes different wavelengths from a signal received at its output and sends the different wavelengths to each of the N inputs. A WDM system is formed using two WDM transceivers which are connected over an optical link and which alternately transmit and receive signals.

Full-duplex wavelength division multiplexing system using single-device

A selected positive coefficient resistor is connected in parallel across a laser, Light Emitting Diode (LED) or amplifier LED (ALED) to adjust the bias current, respectively, to the laser, LED or ALED as a function of temperature so as to maintain a more regulated optical power output therefrom.

Circuit for controlling the output power of an uncooled laser or light

An apparatus and method provides optical multiple wavelength signals using a single, broadband optical source such, for example, as an LED, to generate many independent optical wavelength channels. An optical transmitter includes a wavelength channel defining assembly which resolves the broad spectrum pulses output by the source into discrete wavelength bands constituting respective pulses (i.e., wavelength channels) and which inserts a delay between the bands to define a sequence of individually addressable channels. In accordance with one embodiment of the invention, spectral splicing is achieved by a multiple channel filter, and insertion of the respective delays is achieved by individual fiber sections, each section having a length selected to introduce a particular delay, coupled to the output ports of the router. The inserted delays can be conveniently selected to separate adjacent wavelength channels and thereby minimize the likelihood of crosstalk. Pulses of the thus-resolved channels arrive at different times to a multiplexer which may be configured, for example, as a passive WDM multiplexer or as a star combiner. The resulting sequence of addressable wavelength channels may be supplied to one or more high-speed, broadband modulators, with each modulator being operable to modulate some or all of the channels.

Optical communication system employing spectrally sliced optical source

An apparatus and technique for providing isolation for a signal source utilizing two or more modulators is described. In particular, the apparatus generates a timed sequence of 'open gates' that are synchronized to the data signal which permit transmission in a forward direction, and which attenuate a reverse direction signal. Another embodiment attenuates primarily reflected light signals by utilizing a passive waveguide and a modulator. The passive waveguide provides a propagation delay such that signals reflected from its end facet are attenuated by the modulator. The apparatus is suitable for use as an isolator for a light source in a high-speed optical fiber data transmission system.

Optical modulators as monolithically integrated optical isolators

A lightwave communication system includes an optical distribution system for routing optical signals and a plurality of optical transmitters coupled to the optical distribution system. At least one of the optical transmitters has an amplified light emitting diode for generating an optical spectrum. At least one optical receiver is optically coupled to the optical distribution system.

Passive optical network having amplified LED transmitters

A light source includes a light emitting diode and an optical fiber having a first end coupled to the output of the light emitting diode. A single or multiple transverse mode optical semiconductor amplifier has an input coupled to a second end of the optical fiber. The light source may be fabricated from discrete components or alternatively it may be fabricated as a monolithically integrated device.

Semiconductor light source having a spectrally broad, high power optical

A semiconductor laser has been developed which is capable of efficiently transmitting a predetermined number of modes to an external fiber or waveguide. The laser includes an active gain region disposed in a laser cavity that is formed in a semiconductor material. A lens and a waveguide are also located in the laser cavity. The lens receives optical energy generated by the active gain region and directs this energy into one end of the waveguide. The waveguide transmits the optical energy from the laser to an external fiber or waveguide. The waveguide may be either a single mode waveguide or a multimode waveguide that selects a predetermined number of modes from among all the modes generated by the active region. If a single mode waveguide is employed, the output energy is composed of the fundamental frequency generated by the active region. If a multimode waveguide is employed, the output energy is composed of the predetermined modes selected by the waveguide.

Semiconductor laser having integrated waveguiding lens

An optical device includes a semiconductor optical amplifier and a lens for receiving optical energy from the optical amplifier. The lens and the optical amplifier are monolithically integrated on a common substrate. The optical amplifier may be of the type having a tapered active region. Rather than an optical amplifier, a semiconductor laser may be integrated with the lens. The lens may be formed by changing the refractive index of the waveguide core which is formed in the semiconductor material. This refractive index change may be produced by changing the thickness of a portion of the waveguide core layer.

Semiconductor amplifier or laser having integrated lens

An optical amplifier and photodetector are monolithically integrated, with the photodetector being optically coupled to the optical amplifier through a low radiative loss and low back reflectivity branching waveguide. Because of the low reflectivity, the branching waveguide, although having a truncated wedge tip, is able to redirect a small portion of optical radiation from the amplifier to the photodetector without deleteriously effecting the performance of the optical amplifier. The branching waveguide is realized by employing between the branches of the waveguide, a junction region having a gradual decrease in effective refractive index such as to decrease the difference between the refractive indices at the optical interface of the truncated wedge tip as seen by optical radiation incident thereto from the optical amplifier.

Monolithic integrated optical amplifier and photodetector

An optical branching waveguide having low radiative loss and low back-reflectivity is described. By employing between the branches a region having a gradual decrease in effective refractive index along the direction of optical propagation, the deleterious effect of wedge tip truncation can be reduced. According to the teachings of the invention, this may be accomplished by gradually decreasing the thickness of the optical material along the axis of optical propagation and planarizing the region with an optical material having a lower refractive index than the underlying optical material.

Optical branching waveguide

There are disclosed a method and apparatus for producing laser pulses at two wavelengths alternately by switching the oscillations of a distributed feedback semiconductor laser of the continuous grating type back and forth across the stop band. The necessary shaping of the gain or index of refraction characteristic along the path of the oscillations is accomplished in part by two top electrodes, one of which is longer than the other along that path, and by varying the current supplied to at least one of those electrodes in the appropriate sense. Applications for optical communication and for optical logic are disclosed, the preferred embodiment being a transmitter for an optical communication system with minimal chirp of the optical pulses, in which pulses at one of the wavelengths are modulated at a bit rate exceeding 1 Gigabit by direct-modulation control of the switching of the laser, and the pulses at the other of the two wavelengths are discarded.

Growing community of inventors

Holmdel, NJ, United States of America

Kang-Yih Liou