Gazillion Bits, Inc.

Zuhua Zhu

Shih-Yuan Wang

M Saif Islam

Miao Zhu

Haiqing Wei

A semiconductor optical amplifier (SOA) apparatus and related methods are described. The SOA comprises a signal waveguide for guiding an optical signal along a signal path, and further comprises one or more laser cavities having a gain medium lying outside the signal waveguide, the gain medium being sufficiently close to the signal waveguide such that, when the gain medium is pumped with an excitation current, the optical signal traveling down the signal waveguide is amplified by an evanescent coupling effect with the laser cavity. When the gain medium is sufficiently pumped to cause lasing action in the laser cavity, gain-clamped amplification of the optical signal is achieved. Additional features relating to segmented laser cavities, separate pumping of laser cavity segments, DFB/DBR gratings, current profiling to improve ASE noise performance, coupled-cavity lasers, avoidance of injection locking effects, manipulation of gain curve peaks, integration with a tunable vertical cavity coupler, integration with a photodetector, integration with an RZ signal modulator, and other described features may be used with the evanescent coupling case or with an SOA having a laser cavity gain medium that is coextensive with the gain medium of the signal waveguide.

Semiconductor optical amplifier using laser cavity energy to amplify signal and method of fabrication thereof

A vertical cavity surface-emitting laser (VCSEL) structure and related fabrication methods are described, the VCSEL comprising amorphous dielectric distributed Bragg reflectors (DBRs) while also being capable of fabrication in a single-growth process. Beginning with a substrate such as InP, a first amorphous dielectric DBR structure is deposited thereon, but is limited in width such that some substrate material remains uncovered by the dielectric material. A lateral overgrowth layer is then formed by epitaxially growing material such as InP onto the substrate, the lateral overgrowth layer eventually burying the dielectric DBR structure as well as the previously-uncovered substrate material. Active layers may then be epitaxially grown on the lateral overgrowth layer, and a top dielectric DBR may be deposited thereon using conventional techniques. To save vertical space between DBRs, the first DBR may be deposited in a non-reentrant well formed in the surface of a substrate. A dual lateral overgrowth method for further reducing dislocations above a lower buried dielectric DBR of a VCSEL is also described.

Vertical cavity surface emitting laser with buried dielectric distributed Bragg reflector

A vertical cavity surface emitting laser (VCSEL) structure and fabrication method therefor are described in which a subsurface air, gas, or vacuum current confinement method is used to restrict the area of electrical flow in the active region. Using vertical hollow shafts to access a subsurface current confinement layer, a selective lateral etching process is used to form a plurality of subsurface cavities in the current confinement layer, the lateral etching process continuing until the subsurface cavities laterally merge to form a single subsurface circumferential cavity that surrounds a desired current confinement zone. Because the subsurface circumferential cavity is filled with air, gas, or vacuum, the stresses associated with oxidation-based current confinement methods are avoided. Additionally, because the confinement is achieved by subsurface cavity structures, overall mechanical strength of the current-confining region is maintained.

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San Jose, CA, United States of America

Zuhua Zhu