Applied Optoelectronics, Inc.

Lucent Technologies Inc.

Wen-Yen Hwang

Klaus Alexander Anselm

James Nelson Baillargeon

Jun Zheng

Chih-Hsiang Lin

Stefan J Murry

Alfred Yi Cho

Sung-Nee George Chu

Yu-Hwa Lo

Zuhua Zhu

Yucai Zhou

Keh-Yeng Cheng

A filtered laser array assembly generally includes an array of laser emitters coupled between external modulators and an arrayed waveguide grating (AWG). Each of the laser emitters emits light across a plurality of wavelengths including, for example, channel wavelengths in an optical communication system. The AWG filters the emitted light from each of the laser emitters at different channel wavelengths associated with each of the laser emitters. Lasing cavities are formed between each of the laser emitters and a back reflector coupled to an output of the AWG such that laser output from the laser emitters is provided at the respective channel wavelengths of the reflected, filtered light. The external modulators enable high speed modulation of the laser output. The modulated laser output may then be optically multiplexed to produce an aggregate optical signal including multiple channel wavelengths.

Filtered laser array assembly with external optical modulation and WDM optical system including same

An external cavity laser array system may be used in a WDM optical system, such as a WDM-PON, for transmitting optical signals at multiple channel wavelengths. The system generally includes a plurality of laser emitters (e.g., gain chips) optically coupled to and separated from respective exit reflectors (e.g., tunable narrow-band reflectors), thereby forming an array of external cavity lasers with extended lasing cavities. The exit reflectors may be distributed Bragg reflectors (DBRs) located in the waveguides in an arrayed waveguide grating (AWG). The laser emitters emit a range of wavelengths including multiple channel wavelengths and the DBRs reflect a subset of channel wavelengths including at least a channel wavelength associated with the laser emitter such that lasing occurs at the subset of channel wavelengths. The AWG then filters the emitted laser light at the associated channel wavelengths.

External cavity laser array system and WDM optical system including same

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

The present invention is directed a method of fabricating a VCSEL. First, a substrate with a back surface and a front surface is provided. Then, a first reflector, an active region, and a second reflector are disposed on the front surface. The first reflector is disposed on the front surface. The active region is interposed between the first reflector and the second reflector. Then, anti-reflection features are formed into the back surface of the substrate to reduce specular reflection of light into the active region.

Method and apparatus for reducing specular reflections in semiconductor lasers

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

A substrate including a base substrate, an interfacial bonding layer disposed on the base substrate, and a thin film adaptive crystalline layer disposed on the interfacial bonding layer. The interfacial bonding layer is solid at room temperature, and is in liquid-like form when heated to a temperature above room temperature. The interfacial bonding layer may be heated during epitaxial growth of a target material system grown on the thin film layer to provide the thin film layer with lattice flexibility to adapt to the different lattice constant of the target material system. Alternatively, the thin film layer is originally a strained layer having a strained lattice constant different from that of the target material system but with a relaxed lattice constant very close to that of the target material system, which lattice constant is relaxed to its relaxed value by heating the interfacial bonding layer after the thin film layer is removed from the first semiconductor substrate, so that the thin film layer has an adjusted lattice constant equal to its unstrained, relaxed value and very close to the lattice constant of the target material system.

Alternative substrates for epitaxial growth

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.

Modified distributed bragg reflector (DBR) for vertical cavity surface-emitting laser (VCSEL) resonant wavelength tuning sensitivity control

A method is provided, the method comprising forming a first of n masking layers for a device and forming a first of n phase-shift layers for the device using the first of the n masking layers. The method also comprises forming a second of n masking layers for a device, and forming a second of n phase-shift layers for the device using the second of the n masking layers and forming at least n&plus;1 and at most 2 different optical thicknesses for the device using the n masking layers and the n phase-shift layers.

Patterned phase shift layers for wavelength-selectable vertical cavity surface-emitting laser (VCSEL) arrays

An embodiment of a surface-emitting laser structure includes a first semiconductor region of a first conductivity type coupled to a first contact and a second semiconductor region of the same conductivity type coupled to a second contact. A third semiconductor region of the opposite conductivity type is coupled to a third contact and interposed between the first and second semiconductor regions. An active region is interposed between the first and third regions. In a further embodiment, the laser structure may include a variable refractive index structure interposed between the second and third semiconductor regions. In another embodiment, a surface-emitting laser structure may include an active region between a first semiconductor region of a first conductivity type coupled to a first contact, and a second As semiconductor region of opposite conductivity type coupled to a second contact. A third electrical contact is dielectrically spaced from the second semiconductor region.

Tunable vertical-cavity surface-emitting laser with tuning junction

A vertical-external-cavity surface-emitting laser (VECSEL) is formed by providing a monolithic portion having a first laser cavity mirror and an active region disposed on the first mirror. The cavity is completed with a second laser cavity mirror, such as a DBR, deposited onto the light-receiving end of an optical device, such as an optical fiber. The DBR-on-fiber-end is mounted with respect to the active region to complete the laser cavity and to provide automatic coupling of the output laser light into the fiber.

Optical fiber with mirror for semiconductor laser

A method for fabricating a laser for generating single-longitudinal mode laser light at a lasing wavelength. A semiconductor active region for amplifying, by stimulated emission, light in the laser cavity at the lasing wavelength is formed. A grating is formed adjacent to the active region, the grating having a grating period corresponding to a Bragg wavelength substantially equal to the lasing wavelength. An intermediate section of the grating is removed to result in first and second pluralities of gratings separated by a gratingless intermediate section. First and second grating sections are formed comprising the first and second pluralities of gratings, where the first and second grating sections each have a first effective index of refraction. A gratingless phase-shift section is formed in said intermediate section, the phase-shift section being disposed adjacent to the active region and between the first and second grating sections and having a second index of refraction different than the first index of refraction. The phase-shift section has a length sufficient to impart a phase shift for light at the lasing wavelength sufficient to achieve single-longitudinal mode operation. Alternatively, a grating material layer is deposited adjacent to the active region, the grating material layer having a first section, a second section, and an intermediate section between the first and second sections. Gratings are formed in the first and second sections to form a first grating section in the first section, a second grating section in the second section, leaving a gratingless phase-shift section in the intermediate section.

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Sugar Land, TX, United States of America

Wen-Yen Hwang