Abstract: A sealed integrating reflective enclosure contains a laser diode, coupling optic, and input ends of transport fibers. A detector is positioned to capture stray scattered radiation emanating from the laser diode emitters and rear facets, coupling optic and transport fiber input ends. The detector is positioned such that stray radiation undergoes at least one reflection within the enclosure before being detected by the detector. The detector can be positioned inside the integrating enclosure, or outside the integrating enclosure opposite a detection hole that is sealed by a translucent diffuser or window. The reflected integrated light detected by the detector is an accurate indication of the optical output generated by the laser diode and coupled into the transport fibers.
June 17, 1997
Date of Patent:
May 9, 2000
John Lawrence Nightingale, Matthew Rekow
Abstract: A fiber Bragg grating is used to stabilize the intensity and frequency fluctuations of a diode laser. The diode laser is connected with an opto-mechanical apparatus to the fiber which contains the grating. The grating is formed in the guided-mode region of the optical fiber. The wavelength of maximum grating reflectivity is selected to lie near the maximum of the diode laser gain bandwidth. The magnitude and bandwidth of the grating reflectivity stabilizes the diode laser output without appreciably reducing the optical output power from the end of the fiber. The bandwidth of the optical spectrum of the diode laser is selected depending on the distance of the grating from the diode laser.
Abstract: A III-V group semiconductor laser includes a first clad layer, a first optical waveguide layer, a first barrier layer, an active layer, a second barrier layer, a second optical waveguide layer and a second clad layer formed in this order on a GaAs substrate which is a III-V group compound semiconductor. Each of the first and second clad layers and the first and second optical waveguide layers is of a composition which matches with the GaAs substrate in lattice. The active layer is of a composition which induces compressive strain on the GaAs substrate. Each of the first and second barrier layers is of a composition which induces tensile strain on the GaAs substrate, thereby compensating for the compressive strain induced in the active layer. The ratio of V group elements contained in the first optical waveguide layer is the same as that in the first barrier layer, and the ratio of V group elements contained in the second optical waveguide layer is the same as that in the second barrier layer.
Abstract: An optoelectric connector (12, FIG. 2) is described, which has an outer end (96) constructed to efficiently couple to an optical fiber connector (14) and which has an inner end (47) with electrical contacts (46) for passing currents representing modulated light received or transmitted to an optical cable (20) attached to the optical connector. The optoelectric connector (12) includes a stub (80) or short length of optical fiber with an outer end (82) held at a coupling that couples to the optical fiber (24) of the cable in the same manner as a pair of long optical fibers are connected to minimize losses. The stub has an inner end (84) optically coupled to the optic face (42) of a photoelectric transducer (40) which is coupled to an electrical contact (46).
Abstract: A self-pulsation type semiconductor laser device includes a semiconductor substrate of a first conductive type and a multilayered structure including at least an active layer provided on the semi conductor substrate. The multilayered structure includes a first cladding layer of the first conductive type provided below the active layer, a second cladding layer of a second conductive type having a striped ridge portion provided above the active layer and a saturable absorbing film provided over the second cladding layer. The saturable absorbing film includes an accumulation region for accumulating photoexcited carriers. The accumulating region is provided apart from a surface of the second cladding layer.
Abstract: A radiation-emitting semiconductor diode in the InGaP/InAlGaP material system having a barrier for charge carriers situated between the active layer and one of the cladding layers. Such a diode has an emission wavelength between 0.6 and 0.7 .mu.m and is particularly suitable, when constructed as a diode laser, for serving as a radiation source in, for example, a system for reading and/or writing of optical discs, also because of an increased efficiency. The diode includes a barrier layer comprising only a single barrier layer of AlP, which can be manufactured with a good reproducibility and high yield. A thin AlP barrier layer, having a thickness less than 5 nm, for example 2.5 nm, still provides an excellent barrier.
Abstract: A semiconductor laser has a first conduction type clad layer, an active layer and a second conduction type clad layer formed on a first conduction type semiconductor substrate in this order. An inverted mesa-shaped ridge is formed on a part of the second conduction type clad layer and a first conduction type current stopping layer is formed on each side of the ridge. Each side of the inverted mesa-shaped ridge is curved into a concave surface in a plane perpendicular to the longitudinal direction of the ridge.
Abstract: A semiconductor laser according to the present invention includes: a semiconductor substrate; a multilayer structure provided on the semiconductor substrate, the multilayer structure including an active layer, a pair of cladding layers interposing the active layer, and current confining portion for injecting a current into a stripe-shaped predetermined region of the active layer, wherein the current confining portion includes a first current confining layer formed in regions excluding a region corresponding to the predetermined region of the active layer, the first current confining layer having an energy band gap larger than an energy band gap of the active layer and having a refractive index smaller than a refractive index of the active layer.
March 21, 1997
Date of Patent:
October 26, 1999
Matsushita Electric Industrial Co., Ltd.
Abstract: The gallium nitride compound semiconductor light emitting element includes: a substrate; a first semiconductor multilayer structure including, at least, an active layer, a first cladding layer of a first conductivity type, and a second cladding layer of a second conductivity type, the first and second cladding layers sandwiching the active layer therebetween; a dry etching stop layer of the second conductivity type formed on the first semiconductor multilayer structure; and a second semiconductor multilayer structure formed on the dry etching stop layer.
Abstract: A laser diode controller (30) having a constant current source (60) which supplies current to a laser diode (90) is disclosed. A current shunt switch (40) directs current to either the laser diode (90) or to a bypass circuit (42). A thermal compensator (70) alters a current level of the constant current source (60) as a function of on-time of the laser diode (90) to compensate for changes in optical power conversion efficiency due to temperature changes in the laser diode. A thermo electric cooler controller (80) maintains a constant temperature of a substrate on which the laser diode is mounted. In one embodiment, an array of sample and hold amplifiers (50) eliminates a need for multiple DACs.
May 30, 1997
Date of Patent:
October 12, 1999
Eastman Kodak Company
Robert W. Spurr, Seung H. Baek, Thomas A. Mackin, William R. Markis, Kurt M. Sanger
Abstract: Multiple element laser diode assembly incorporating a cylindrical microlens and at least one of an astigmatism correcting element and a collimating element. The use of a single purpose cylindrical microlens, for instance for circularizing a beam of laser light output from said diode, in operative combination with at least one additional optical element for correcting astigmatism and for collimating the beam enables the passive mounting of the several optical elements of the assembly without an active alignment step. The cylindrical microlens may incorporate as single powered surface, as may the astigmatism correction element. Alternatively, the astigmatism correction element may comprise a tilted optical plate. The collimating lens may be a spherical lens.
Abstract: A quantum-dot cascade laser which eliminates undesirable single phonon decays associated with quantum-well devices. The elimination of single phonon decays is realized by a three-dimensional confinement resulting in a several-order-of-magnitude reduction in the threshold current. Vertical radiative transitions are employed within single quantum dots contained by Bragg reflectors. Dot size, dot density and dot uniformity requirements are presented along with several embodiments.
Abstract: A distributed feedback semiconductor laser diode includes an active layer for generating stimulated emission light and also includes a diffraction grating. The diffraction grating serves as a structure for providing a refractive index distribution and a gain distribution where the refractive index and the gain for the stimulated emission light exhibit a periodical change at an identical single period in the guiding direction of the stimulated emission light. A distributed feedback based on refractive index coupling and a distributed feedback based on gain coupling coexist in the distributed feedback semiconductor laser diode. The diffraction grating includes a phase discontinuous section where a phase of the periodical change of the refractive index and the gain is discontinuous. The phase discontinuous section is configured so that the phase shifts are within a range greater than 0 ?rad! but less than .pi. ?rad!, or within a range greater than .pi. ?rad! but less than 2.pi. ?rad!.
Abstract: A semiconductor laser device comprises a cladding layer of a first conductivity type, an active layer, a cladding layer of a second conductivity type, and a current blocking layer having a stripe-shaped opening having a predetermined width W for restricting a current path and forming the current path, and having a larger band gap than that of the cladding layer of the second conductivity type and having a smaller refractive index than that of the cladding layer of the second conductivity type. A difference .DELTA.n between effective refractive indexes in a region, which corresponds to the opening, in the active layer and an effective refractive index in a region, which corresponds to both sides of the opening, in the active layer and the width W (.mu.m) of the opening are so set as to satisfy a predetermined relationship. The difference .DELTA.
Abstract: A monolithic vertical optical cavity device built up along a vertical direction. The device has a bottom Distributed Bragg Reflector (DBR), a Quantum Well (QW) region consisting of least one active layer grown on top of the bottom DBR by using a Selective Area Epitaxy (SAE) mask such that the active layer or layers exhibit a variation in at least one physical parameter in a horizontal plane perpendicular to the vertical direction and a top DBR deposited on top of the QW region. A spacer is deposited with or without SAE adjacent the QW region. The device has a variable Fabry-Perot distance defined along the vertical direction between the bottom DBR and the top DBR and a variable physical parameter of the active layer. The varying physical parameter of the active layers is either their surface curvature and/or the band gap and both of these parameters are regulated by SAE. The monolithic vertical cavity device can be used as a Vertical Cavity Surface Emitting Laser (VCSEL) or a Vertical Cavity Detector (VCDET).
March 30, 1998
Date of Patent:
September 28, 1999
Bandwidth Unlimited, Inc.
Gabriel S. Li, Wupen Yuen, Constance J. Chang-Hasnain
Abstract: The present invention also provides another semiconductor multilayer carrier injection structure in a semiconductor laser. The semiconductor multilayer carrier injection structure comprises the following elements. The semiconductor multilayer carrier injection structure includes a multiple quantum well active layer comprising alternating laminations of quantum well layers made of a first compound semiconductor having a first energy band gap and potential barrier layers made of a second compound semiconductor having a second energy band gap larger than the first energy band gap. Each of the quantum well layers has an electron ground state of quantum energy levels of electrons and a hole ground state of quantum energy levels of holes. The semiconductor multilayer carrier injection structure also includes a first carrier injection guide layer being provided in contact with a first lateral end portion of the multiple quantum well active layer.
Abstract: A semiconductor laser device according to the present invention includes: a semiconductor substrate having a first conductivity type; and a semiconductor multilayer structure provided on the semiconductor substrate, the semiconductor multilayer structure including an active layer. The semiconductor multilayer structure includes: a lower cladding layer provided below the active layer, the lower cladding layer having the first conductivity type, an upper cladding structure provided above the active layer, the upper cladding structure having a second conductivity type; and a cap layer provided above the upper cladding structure. A ridge is formed in the upper cladding structure, and a width of a lower face of the cap layer is larger than a width of an upper face of the ridge.
Abstract: A laser diode driving apparatus produces a simple write signal having an attenuated waveform to drive the laser diode. A laser diode emits laser light on an optical disk according to a write signal to record data thereon. A laser diode driver outputs a predetermined, plurality of write power values each being different from each other. A write control signal generator calculates widths of a kick pulse and a brake pulse corresponding to the pulse width of the received NRZI signal, and generates write control signals in a predetermined order for controlling write power values corresponding to the calculated widths of the kick pulse and the brake pulse. A write signal generator supplies a write signal to the laser diode using a plurality of the write power values according to the write control signals generated by the write control signal generator. Accordingly, a write domain can be made to be close to a distinct oval.
Abstract: An AlGaInP-based buried-ridge semiconductor laser includes an n-type GaAs current blocking layer 8 buried in opposite sides of a ridge stripe portion 7 which is made of an upper-layer portion of a p-type AlGaInP cladding layer 4, p-type GaInP intermediate layer 5 and p-type GaAs contact layer 6. The ridge stripe portion 7 includes tapered regions 7a having the length of L1 at cavity-lengthwise opposite ends of the ridge stripe portion 7.
Abstract: An optical semiconductor apparatus includes a substrate, a first region formed on the substrate, a second region formed on the substrate, and a stimulating unit. The first region includes a first waveguide which extends in a light propagation direction and is constructed so as to permit light waves in two different polarization modes to be propagated in the propagation direction. The first waveguide contains a first active region which is constructed such that a gain for one of the different polarization modes is dominant. The second region includes a second waveguide which extends in the propagation direction, is coupled to the first waveguide and is constructed so as to permit light waves in the different polarization modes to be propagated in the propagation direction. The second waveguide contains a second active region which is constructed such that a gain for the other of the different polarization modes is dominant.