Coherent light generators – Particular resonant cavity – Distributed feedback
Reexamination Certificate
1999-07-20
2003-09-23
Davie, James (Department: 2828)
Coherent light generators
Particular resonant cavity
Distributed feedback
Reexamination Certificate
active
06625195
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
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FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
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REFERENCE TO MICROFICHE APPENDIX
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TECHNICAL FIELD OF INVENTION
This invention relates to semiconductor diode lasers, or more specifically to a semiconductor diode laser called a (VCSEL) “Vertical Cavity Surface Emitting Laser”, which is a device that uses a process known as recombination radiation to produce laser-light emissions. These semiconductor diode lasers have vertical cavities, which amplify into laser emissions the photonic radiation produced by a double-heterostructure active-region. Comprised, as a multilayered vertical structure, having a substrate, an electronic and optically pumped double-heterostructure light-emitting diode active-region, and two feedback-providing contra-positioned light-reflecting structures defining a resonant cavity.
BACKGROUND OF THE INVENTION
Currently, VCSELs use, as their main photon producing structures a single double-heterostructure light emitting diode active-region. Typically, a double-heterostructure “Light Emitting Diode” (LED) is constructed from latticed-matched extrinsic semiconductor binary materials like (GaAs) “Gallium-Arsenide”, (InP) “Indium-Phosphide”, and (GaSb) “Gallium-Antimonide”. Additionally, a double-heterostructure LED can also be constructed from latticed-matched extrinsic semiconductor ternary materials like (GaAlAs) “Gallium-Aluminum-Arsenide”, or constructed from latticed-matched extrinsic semiconductor quaternary materials like (InGaAsP) “Indium-Gallium-Arsenic-Phosphide”, and (InGaAsSb) “Indium-Gallium-Arsenic-Antimonide”. Typically, a single double-heterostructure LED active-region will contain either a “Single Quantum Well” (SQW) active-area (i.e., used in what is sometimes called a SQW laser), which is constructed from a single extrinsic semiconductor material, or a “Multiple Quantum Well” (MQW) active-area (i.e., used in what is sometimes called a MQW laser), which is constructed from several extrinsic semiconductor materials.
In addition, recombination produced optical-radiation emitted by current VCSELs is far from ideal. For example, the coherence properties of recombination radiation emissions produced by prior-art VCSELs is most often of poor quality, with their coherence measured to be somewhere between the laser radiation emitted by a low-pressure gas laser and an incoherent line-source. Additionally, the recombination radiation produced emissions created by prior-art VCSELs is not collimated, but divergent having a total divergence of about “30” degrees from a VCSEL emitter's top-surface edge. Generally, all prior-art VCSEL designs use a cavity-external and microscopic collimating lens to correct the problem of laser beam divergence. Adjustment of a VCSEL's divergent light-rays into collimated and parallel traveling light-rays is accomplished when a cavity-external collimating lens has been located several microns from a VCSEL emitter's top horizontal surface.
Furthermore, to correct current VCSEL laser beam incoherence and laser beam divergence problems a new type of VCSEL design is required. Therefore, any problems presented above are substantially solved by the present invention, while any purposes presented above arc realized as well in the present invention's Phase Conjugated Vertical Cavity Surface Emitting Laser design, which is described in greater detail within the preferred embodiments written below.
SUMMARY OF THE INVENTION
In accordance with the present invention, a Phase Conjugated Vertical Cavity Surface Emitting Laser comprises a cavity folding corner-cube shaped prism waveguide having three internal reflecting prisms that provide a cavity folding transverse redirection, polarity stabilization, and a retro-reflection of intracavity produced fundamental photonic radiation; four electrically unisolated double-heterojunction LED structures constructed from interference forming nonlinear semiconductor materials (e.g., Gallium-Arsenide, Indium-Gallium-Arsenide, and/or Aluminum-Gallium-Arsenide) that will provide electronic production, optical amplification, and phase conjugated reflection of intracavity produced fundamental photonic radiation; and a partial reflecting feedback providing mirror structure capable of reflecting a sufficient amount of undiffused intracavity produced optical radiation into the laser's nonlinear and laser-active semiconductor material for further amplification, while providing an apparatus that produces frequency-selected output of wavelength-specific monochromic and amplified photonic radiation.
Objects and Advantages
Accordingly, besides the objects and advantages of a phase conjugated vertical-cavity surface-emitting laser described in the above patent, several other objects and advantages of the present invention are:
(a) To provide a phase conjugated vertical-cavity surface-emitting laser that creates a high output of narrow-linewidth amplified light using a cavity folding internal reflecting corner-cube shaped prism waveguide comprised from a single layer of optically transparent material;
(b) To provide a phase conjugated vertical-cavity surface-emitting laser that is inexpensive to manufacture, because it has eliminated the expensive epitaxial deposition of a primary quarterwave mirror stack assembly comprised as an multitude of quarterwave thick epitaxial deposited alternating layers that are constructed from refractive opposing materials and replaced it with a single corner-cube shaped prism waveguide, which is constructed from a single inexpensive layer of sputter or epitaxially deposited optically transparent material;
(c) To provide a phase conjugated vertical-cavity surface-emitting laser that uses two graded confinement cladding-layers to generate higher-output of laser emissions;
(d) To provide a phase conjugated vertical-cavity surface-emitting laser, which produces a more effective output gain by using two graded confinement cladding-layers within each active-region to lower the heat produced by electrical resistance that occurs between current conducting contact-layers and their adjacent cladding-layers;
(e) To provide a phase conjugated vertical-cavity surface-emitting laser, which increases optical confinement with the addition of total internal reflecting cladding material to the surrounding vertical and outermost wall surfaces of the phase conjugated vertical-cavity surface-emitting laser's folded vertical-cavity(s);
(f) To provide a phase conjugated vertical-cavity surface-emitting laser, which can be configured and controlled as a single phase conjugated vertical-cavity surface-emitting laser device;
(g) To provide a phase conjugated vertical-cavity surface-emitting laser, which can be configured as a single phase conjugated vertical-cavity surface-emitting laser-array comprising a multitude of phase conjugated vertical-cavity surface-emitting lasers, which can be controlled as a single group of phase conjugated vertical-cavity surface-emitting lasers or controlled as a single group of independently controlled phase conjugated vertical-cavity surface-emitting lasers;
(h) To provide a phase conjugated vertical-cavity surface-emitting laser or a phase conjugated vertical-cavity surface-emitting laser-array, which can be manufactured at the same time, as a single integrated semiconductor device, using the same semiconductor and substrate material used to construct the laser-array's control-circuitry;
(j) To provide a phase conjugated vertical-cavity surface-emitting laser, which replaces a primary quarterwave mirror-stack assembly with a cornercube prism waveguide, if comprised of quartz or fused silica, will totally reflect one-hundred percent all frequencies of optical radiation that enters the waveguide's top horizontally-flat front-face surface;
(k) To provide a phase conjugated vertical-cavity surface-emitting laser, which inexpensively constructs its corner-cube shaped prism waveguide using a well-known reactive ion-milling process to slice out the waveguide's pr
Davie James
Kirkpatrick & Lockhart LLP
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