Applied Optoelectronics, Inc.

Lucent Technologies Inc.

Agere Systems Guardian Corp.

Agere Systems Optoelectronics Guardian Corp.

Klaus Alexander Anselm

Wen-Yen Hwang

Jun Zheng

James Nelson Baillargeon

Chih-Hsiang Lin

Huanlin Zhang

Alfred Yi Cho

Stefan J Murry

Hung-Lun Chang

Dion McIntosh-Dorsey

I-Lung Ho

Yi Wang

Sung-Nee George Chu

Jeffery L Johnson

Rajesh Bikky

Stephen Hu

Greg Pickrell

Nahid Sultana

Jae Yoon Um

Guipeng Luo

Chia Chen David Wong

Dion Mcintosh-Dorsey

A tunable laser with multiple in-line sections including sampled gratings generally includes a semiconductor laser body with a plurality of in-line laser sections configured to be driven independently to generate laser light at a wavelength within a different respective wavelength range. Sampled gratings in the respective in-line sections have the same grating period and a different sampling period to produce the different wavelengths. The wavelength of the light generated in the respective laser sections may be tuned, in response to a temperature change, to a channel wavelength within the respective wavelength range. By selectively generating light in one or more of the laser sections, one or more channel wavelengths may be selected for lasing and transmission. By using sampled gratings with the same grating period in the multiple in-line sections, the multiple section tunable laser may be fabricated more easily.

Tunable laser with multiple in-line sections including sampled gratings

A parallel cavity tunable laser generally includes a semiconductor laser body defining a plurality of parallel laser cavities with a common output. Each of the parallel laser cavities is configured to be driven independently to generate laser light at a wavelength within a different respective wavelength range. The wavelength of the light generated in each of the laser cavities may be tuned, in response to a temperature change, to a channel wavelength within the respective wavelength range. The laser light generated in each selected one of the laser cavities is emitted from the common output at a front facet of the laser body. By selectively generating light in one or more of the laser cavities, one or more channel wavelengths may be selected for lasing and transmission.

Tunable laser including parallel lasing cavities with a common output

A two-section semiconductor laser includes a gain section and a modulation-independent grating section to reduce chirp. The modulation-independent grating section includes a diffraction grating for reflecting light and forms a laser cavity with the gain section for lasing at a wavelength or range of wavelengths reflected by the diffraction grating. The gain section of the semiconductor laser includes a gain electrode for driving the gain section with at least a modulated RF signal and the grating section includes a grating electrode for driving the grating section with a DC bias current independent of the modulation of the gain section. The semiconductor laser may thus be directly modulated with the modulated RF signal without the modulation significantly affecting the index of refraction in the diffraction grating, thereby reducing chirp.

Two-section semiconductor laser with modulation-independent grating section to reduce chirp

A dual testing system and method is used to perform both optical power and wavelength measurements on laser light emitted from a laser diode, such as a chip-on-submount (COS) laser diode or a laser diode in a bar laser. A testing fixture may be used to facilitate both measurements by simultaneously detecting the light for performing a first test including the optical power measurement(s) and reflecting the light for performing a second test including the wavelength measurement(s). The testing fixture may include an angled photodetector and an optical coupling system such as a collimating lens, a focal lens and an optical waveguide. The testing fixture may be electrically connected to an optical power testing module, such as a light-current-voltage (LIV) testing module, for performing the optical power measurement(s) and may be optically coupled to a wavelength measurement module, such as an optical spectrum analyzer (OSA) for performing the wavelength measurement(s).

System, method and fixture for performing both optical power and wavelength measurements of light emitted from a laser diode

Individual channels of a multiplexed laser array in a multi-channel optical transmitter are monitored at an output of an optical multiplexer. The monitoring may be used to confirm proper operation of each of the channels in the multiplexed laser array and/or to perform wavelength locking on each of the channels. Monitoring at the output of the optical multiplexer avoids the use of multiple photodetectors coupled directly to multiple lasers in the multiplexed laser array. The multiplexed laser array generally includes a plurality of laser emitters optically coupled to an optical multiplexer such as an arrayed waveguide grating (AWG). An optical transmitter with a monitored multiplexed laser array may be used, for example, in an optical line terminal (OLT) in a wavelength division multiplexed (WDM) passive optical network (PON) or in any other type of WDM optical communication system capable of transmitting optical signals on multiple channel wavelengths.

Monitoring a multiplexed laser array in an optical communication system

An improved scribe etch process for semiconductor laser chip manufacturing is provided. A method to etch a scribe line on a semiconductor wafer generally includes: applying a mask layer to a surface of the wafer; photolithographically opening a window in the mask layer along the scribe line; etching a trench in the wafer using a chemical etchant that operates on the wafer through the window opening, wherein the chemical etchant selectively etches through crystal planes of the wafer to generate a V-groove profile associated with the trench; and cleaving the wafer along the etched trench associated with the scribe line through application of a force to one or more regions of the wafer.

Scribe etch process for semiconductor laser chip manufacturing

A semiconductor laser diode with integrated heating generally includes a lasing region and a heating region integrated into the same semiconductor structure or chip. The lasing region and the heating region include first and second portions, respectively, of the semiconductor layers forming the semiconductor structure and include first and second portions, respectively, of the active regions formed by the semiconductor layers. Separate laser and heater electrodes are electrically connected to the respective lasing and heating regions for driving the respective lasing and heating regions with drive currents. The heating region may thus be driven independently from the lasing region, and heat may be conducted through the semiconductor layers from the heating region to the lasing region allowing the temperature to be controlled more efficiently.

Semiconductor laser diode with integrated heating region

A directly modulated distributed feedback (DFB) laser with improved optical field uniformity and mode stability may include a laser cavity and a distributed reflector and/or external reflectors. The distributed reflector may be a Bragg grating and may extend asymmetrically over a only portion of the laser cavity. The external reflectors may themselves be distributed Bragg reflectors and may have unequal reflectances. Optical field uniformity may be improved by adjusting the length and/or position of the distributed reflector in the laser cavity. Optical field uniformity may be improved by adjusting a coupling strength parameter, which is a function of a coupling coefficient, &#x3ba;, and the length of the distributed reflector.

Distributed feedback laser with improved optical field uniformity and mode stability

Methods for fabricating a VCSEL having current confinement, the VCSEL having a substrate, a semiconductor active region, and a bottom mirror disposed between the substrate and the active region. A first top spacer layer is epitaxially grown on the active region, the first top spacer layer comprising a current-spreading buffer layer disposed on the active region, a current-confinement layer disposed on the buffer layer, and a current-spreading platform layer disposed on the current-confinement layer, wherein the combined thickness of the platform and current-confinement layers is less than the thickness of the buffer layer. A current-confinement structure having an annular region of enhanced resistivity and a central aperture of comparatively lower resistivity is formed in the current-confinement layer using ion implantation. Subsequently, epitaxial regrowth is performed to form a second top spacer layer on the platform layer, said second top spacer layer comprising a top current-spreading layer. The resulting current-confinement structure is the result of a shallower ion implantation and thus has more precise dimensions and can be closer to the active region.

Method for fabricating a VCSEL with ion-implanted current-confinement structure

A surface-emitting laser, such as a VCSEL, for generating single-transverse mode laser light at a lasing wavelength, has a first mirror and a second mirror positioned so as to define a laser cavity therebetween, and a semiconductor active region disposed between the first and second mirrors for amplifying, by stimulated emission, light in the laser cavity at the lasing wavelength. An annular antiguide structure is disposed within the laser cavity and between the active region and one of the first and second mirrors, the annular antiguide structure comprising an antiguide material and having a central opening, the central opening comprising a second material having an index of refraction for light at the lasing wavelength smaller than that of the antiguide material, whereby the annular antiguide structure causes preferential antiguiding of higher order transverse lasing modes in the laser cavity.

VCSEL with antiguide current confinement layer

A multiple reflectivity band reflector (MRBR) includes a stack of dielectric layers, arranged so that the reflector has a reflectivity profile comprising a plurality of reflectivity bands, e.g. at least first and second wavelength bands with reflectivity above a lasing threshold reflectivity, separated by a third wavelength band between the first and second wavelength bands having reflectivity below the lasing threshold reflectivity. A laser having at least a first mirror and an MRBR as the second mirror has a laser cavity, at least a portion of which is defined by the first mirror and the MRBR. An active region located within the laser cavity contains a material that is capable of stimulated emission at one or more wavelengths in the first and second wavelength bands. The gain spectrum of the laser is adjusted to select one of the first and second wavelength bands, thereby providing for lasing at a wavelength within the selected wavelength band. The laser may be, e.g., a monolithic VCSEL or a one-section or two-section external-cavity VECSEL having the MRBR as one of its cavity mirrors.

Multiple reflectivity band reflector

A monitored laser system has a laser having a first mirror; an exit mirror, at least a portion of a laser cavity defined by the first mirror and the exit mirror; and an active region located in the laser cavity, the active region containing a material that is capable of stimulated emission at one or more wavelengths of laser light within a tuning range of the laser. A multiple reflectivity band reflector (MRBR) is coupled to at least a portion of laser light emitted from the laser and transmits filtered laser light. The MRBR has a plurality of layers of material arranged in parallel such that the reflector has a plurality of reflectivity peaks within the tuning range, each reflectivity peak separated from neighboring reflectivity peak by a reflectivity trough having a trough minimum, said reflectivity peaks characterized by a peak profile and said trough minima between said reflectivity peaks characterized by a trough profile. At least one of the peak and trough profiles has a substantially non-constant relationship of wavelength to reflectivity. A first photodiode coupled to at least a portion of the filtered laser light produces an output based on the amount of light received. The emitted wavelength of the laser is adjusted toward a desired wavelength within the tuning range based at least in part on the output of the first photodiode.

Multiple reflectivity band reflector with non-uniform profile and laser system employing same for laser wavelength monitoring

Laser having multiple reflectivity band reflector

A monitored laser system includes a laser with a first mirror and an exit mirror. The laser also has a laser cavity defined at least in part by the first mirror and the exit mirror. Within the laser cavity is an active region that contains material that is capable of stimulated emission at one or more wavelengths such that laser light is emitted from the laser. A power source is coupled to the active region. A multiple reflectivity band reflector (MRBR) is coupled to at least a portion of the emitted laser light. The MRBR has at least first and second wavelength bands with reflectivity above a particular reflectivity separated by at least a third wavelength band having reflectivity below the particular reflectivity. A first photodiode is coupled to at least a portion of the filtered laser light and produces an output based on the amount and wavelength of light received. A means for adjusting the emitted wavelength of the laser toward a particular wavelength in one of the at least first, second, and third wavelength bands based at least in part on the output of the first photodiode.

Method and system employing multiple reflectivity band reflector for laser wavelength monitoring

An optical device has at least one reflector disposed in an optical cavity. The reflector has a plurality of mirror pairs each comprising a pair of layers, each layer of each mirror pair having an index of refraction different than that of the other layer of the respective mirror pair. A tuning layer is disposed in the reflector, the tuning layer having an index of refraction different from that of the layers of the mirror pairs. In another embodiment, the reflector has first and second adjacent reflector sections, each reflector section having a respective plurality of mirror pairs where the difference in refractive index of a mirror pair's layers defines a refractive index contrast for the mirror pair. The mirror pairs of the first reflector section have a refractive index contrast different than that of the second reflector section, and a tuning layer is disposed in the optical cavity adjacent to the second reflector section and having an index of refraction different from that of the layers of the mirror pairs of the second reflector section.

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Sugar Land, TX, United States of America

Klaus Alexander Anselm