Lucent Technologies Inc.

Agere Systems Guardian Corp.

Triquint Technology Holding Co.

Agere Systems Optoelectronics Guardian Corp.

John Evan Johnson

David Alan Ackerman

Leonard Jan-Peter Ketelsen

Charles H Joyner

Christopher Richard Doerr

Uziel Koren

Lawrence Warren Stulz

Sung-Nee George Chu

Liming Zhang

Dirk Joachim Muehlner

Sharon K Sputz

Kishore K Kamath

William R Heffner

David V Lang

Eric J Dean

Janet L Lentz

C Lewis Reynolds, Jr

Rudolph Conrad Schweizer

A method of increasing the monomolecular recombination and the immunity to noise of a continuously tunable laser is disclosed. A concentration of recombination centers in the range of about 1&#xd7;10cmto about 1&#xd7;10cmin the tuning region of the laser device is achieved by doping the waveguide layer with impurity atoms, by irradiating the waveguide layer with high energy particles or by varying the growth conditions of the waveguide layer to introduce native point defects due to lattice mismatch. This way, the monomolecular recombination is increased and the radiative recombination over low current ranges is reduced. By increasing the monomolecular recombination, the immunity to noise is improved but the tuning efficiency is reduced. Nevertheless, only a minimal effect on the tuning efficiency is noted over high current ranges and, therefore, the overall tuning range is only insignificantly changed.

Wavelength tunable laser and method of formation

A process evaluates an aging property of a distributed Bragg reflector (DBR) laser. The process includes illuminating a Bragg grating of the distributed Bragg reflector (DBR) laser with light while the DBR laser is both supplied a tuning current and not lasing. The process also includes performing an action to the DBR laser responsive to a wavelength of a Bragg peak in a portion of the light reflected by the Bragg grating and a value of the tuning current supplied during the illuminating.

Aging in tunable semiconductor lasers

The invention is a semiconductor device, and a method of fabrication, where a waveguide layer in which light is propagated and an integral photodetector are formed in the device. A light absorbing layer of the photodetector includes a portion of the waveguide layer which is modified to absorb a portion of the light while transmitting the remainder of the light. Additional components, such as a laser, optical amplifier and modulator can be included with the photodetector.

Optoelectronic device with power monitoring tap

A monolithically integrated light source and frequency discriminator has a section in which a single frequency optical signal is produced and a section in which the frequency is sensed. The output of the optical discriminator is connected to a controller for stabilizing the output frequency of the light source.

Apparatus and method for stabilizing the frequency of a light source

A hybrid integrated optical transmitter comprising a wavelength selectable laser (WSL) source coupled to an optical amplifier/modulator has been realized. Disposed between the optical combiner and the optical amplifier/modulator is an &ldquo;optical isolator.&rdquo; The optical isolator includes at least a Faraday rotator and, either solely or in combination with a single polarizer and/or half-wave plate is used to selectively rotate and pass polarized light egressing from the wavelength selectable laser source. Optical isolation is achieved by the egressing radiation from and back reflections incident on the laser source being at two mutually exclusive orthogonal polarization states or by the reflections being totally extinguished. Advantageously, the laser source is unresponsive to orthogonally polarized light, and hence any unwanted back reflections do not substantially affect the operating characteristics of the laser(s). Optical isolation may be further improved, however, with the use of an additional polarizer positioned in front of the Faraday rotator to totally extinguish the polarized back reflections. Preferably, a latching Faraday rotator is used. As such, permanent magnets are not needed to maintain the latching Faraday rotator in its saturated state, and substantially reduces cost, size and complexity of the transmitter package. The wavelength selectable laser source is integrated on a single substrate with an optical combiner that directs the radiation to the optical amplifier/modulator, which is integrated on a second substrate. Alternatively, the laser source and optical combiner may be integrated on different substrates.

Hybrid integration of a wavelength selectable laser source and optical amplifier/modulator

A method of manufacturing and testing a laser device that facilitates in-wafer testing of the laser device includes forming the laser device on a wafer and forming a light detecting device on the wafer adjacent to the laser device. The laser device should include a grating. The method further includes causing the laser device to lase while in the wafer and detecting light generated from the laser device with the light detecting device. Finally, the method includes obtaining an electro-optic parameter of the laser device from the detected light.

In-wafer testing of DFB semiconductor lasers

An optical transmitter for generating any one of N carrier signals for use in an M-channel WDM system (M&gE;N), each channel operating at a different carrier wavelength &lgr;,(s&equals;1, 2 . . . M), includes an optical source for generating the carrier signals at any one of multiplicity of N wavelengths &lgr;,(i&equals;1, 2 . . . N), where (1&lE;N&lE;M). A first controller selects a particular one of the wavelengths &lgr;,at which the source operates. An optical modulator receives the carrier signal corresponding to the selected wavelength &lgr;,and impresses information on the received signal. The modulator has a characteristic electronic bandgap and a wavelength &lgr;,corresponding thereto. At a given temperature, &lgr;,is offset from each &lgr;,by an amount &Dgr;&lgr;,. For each wavelength &lgr;,there is a predetermined value of &Dgr;&lgr;,which delivers preferred (e.g., optimum) transmission performance. In general, however, the actual &Dgr;&lgr;,may not be equal to the predetermined &Dgr;&lgr;,for all values of i. The difference between the actual &Dgr;&lgr;,and the predetermined &Dgr;&lgr;,is termed the detuning error. In accordance with one aspect of my invention, the transmitter includes a second controller for minimizing the detuning error. In a preferred embodiment, the second controller changes the temperature of the modulator as the wavelength of the source is changed (i.e., as different &lgr;,are selected) so that &Dgr;&lgr;,is controlled according to the above criterion. In one embodiment, in which the wavelength of the source can be tuned independent of the temperature of the modulator, the second controller maintains the detuning error essentially zero for all values of i selected. In another embodiment, in which the wavelength of source is not tuned independent of the temperature of the modulator, &lgr;,is detuned from &lgr;,by a predetermined amount related to the rate of change of &lgr;,and &lgr;,with respect to temperature.

Optical transmitter for WDM systems

A method of fabricating an expanded beam optical waveguide device (e.g., a laser), comprises the steps of (a) forming a first semiconductor waveguide region having first and second sections of different thickness and an intermediate vertical taper section of varying thickness coupling the first and second sections to one another, the first waveguide region being effective to expand the size of the beam as it propagates from the first section to the second section, (b) forming a second semiconductor region (e.g., a laser active region) on the first waveguide region, (c) etching the second region so as to form an essentially vertical first surface of length A-B which extends obliquely across the propagation axis of the device, (d) forming a third semiconductor region (e.g., a cladding region) on the second region and over the first surface, and (e) etching an elongated mesa along the axis, the mesa extending through at least the second region and the first surface so as to form a second waveguide region having an oblique, essentially second vertical surface which has a length a-b&lt;A-B and which is a subsection of the first surface, the second surface forming an asymmetric horizontal taper effective to optically couple the beam between the second waveguide region and the first waveguide region. Also described is a monolithically integrated optical amplifier and electroabsorption modulator with a dual waveguide expanded beam device fabricated by the inventive method.

Method of fabricating an expanded beam optical waveguide device

In accordance with the present invention, a wavelength selectable laser source comprises a tunable pump source, an array of waveguide lasers for emitting light at respectively different wavelengths and a router for directing light from the pump source to an appropriate waveguide laser. A second router can be used to direct all laser outputs to a common output waveguide. The result is a wavelength selectable, stable signal source. In preferred embodiments the routers are dense wavelength-division multiplexers (DWDMs) and the waveguide lasers are rare-earth doped fiber lasers. Alternative embodiments provide a variety of ways of routing the pumping source.

Wavelength selectable laser source

Methods and apparatus for stabilizing or otherwise controlling wavelength in tunable semiconductor lasers and other optical sources. A tunable semiconductor laser includes a gain section and at least one tuning section. Spontaneous emission (SE) from the tuning section is detected and used in a feedback control loop to control the amount of current applied to the tuning section. The SE may be detected using an integrated detector on the semiconductor laser chip, an external detector arranged adjacent the chip to detect SE emitted from a side of the tuning section, or an external detector arranged to detect SE coupled from an optical fiber or other signal line connected to an optical signal output of the laser. The feedback control loop may operate to maintain the detected SE at a constant level, such that the current applied to the tuning section is adjusted to compensate for the effects of aging and the laser output wavelength is thereby stabilized. The invention may also be implemented using multiple feedback control loops to control the current supplied to corresponding multiple tuning sections of a given optical source. Each of the multiple feedback control loops may operate to maintain the SE detected from a corresponding one of the tuning sections at a constant level, such that the output wavelength is stabilized.

Wavelength stabilization in tunable semiconductor lasers

An automatic access code dialer stores a user entered telephone number and compares the first three digits of the stored telephone number to a list of three digit numbers that specify telephone exchanges that may be contacted using an alternative shorthaul long distance service provider. If the stored digits match one of the numbers on the list, the user entered telephone number and an access code for a alternative service provider are passed to the telephone network. If the stored digits do not match one of the numbers on the list, the user entered telephone number is passed to the telephone network.

Growing community of inventors

New Providence, NJ, United States of America

John Evan Johnson