The present disclosure relates to a semiconductor light emitting device, comprising: a plurality of semiconductor layers, including a first semiconductor layer having a first conductivity, a second semiconductor layer having a second conductivity different from the first conductivity, and an active layer interposed between the first semiconductor layer and the second semiconductor layer, generating light via electron-hole recombination; a first electrode, supplying either electrons or holes to the plurality of semiconductor layers; a second electrode, supplying, to the plurality of semiconductor layers, electrons if the holes are supplied by the first electrode, or holes if the electrons are supplied by the first electrode; a non-conductive distributed bragg reflector coupled to the plurality of semiconductor layers, reflecting the light from the active layer; and a first light-transmitting film coupled to the distributed bragg reflector from a side opposite to the plurality of semiconductor layers with respect to the non-conductive distributed bragg reflector, with the first light-transmitting film having a refractive index lower than an effective refractive index of the distributed bragg reflector.

Semiconductor Light Emitting Device

Optical apparatus includes first and second diffractive optical elements (DOEs) arranged in series to diffract an input beam of radiation. The first DOE is configured to apply to the input beam a pattern with a specified divergence angle, while the second DOE is configured to split the input beam into a matrix of output beams with a specified fan-out angle. The divergence and fan-out angles are chosen so as to project the radiation onto a region in space in multiple adjacent instances of the pattern.

Optical pattern projection

Optical apparatus includes a beam source, which is configured to generate an optical beam having a pattern imposed thereon. A projection lens is configured to receive and project the optical beam so as to cast the pattern onto a first area in space having a first angular extent. A field multiplier is interposed between the projection lens and the first area and is configured to expand the projected optical beam so as to cast the pattern onto a second area in space having a second angular extent that is at least 50% greater than the first angular extent.

Projectors of structured light

Optical apparatus includes a semiconductor substrate and an edge-emitting radiation source, mounted on a surface of the substrate so as to emit optical radiation along an axis that is parallel to the surface. A reflector is fixed to the substrate in a location on the axis and is configured to reflect the optical radiation in a direction that is angled away from the surface. One or more optical elements are mounted on the substrate so as to receive and transmit the optical radiation reflected by the reflector.

Integrated photonics module for optical projection

A semiconductor laser apparatus comprises a first semiconductor laser device that emits a blue-violet laser beam, a second semiconductor laser device that emits a red laser beam, and a conductive package body. The first semiconductor laser device has a p-side pad electrode and an n-side electrode. The p-side pad electrode and n-side electrode of the first semiconductor laser device are electrically isolated from the package body. The p-side pad electrode of the first semiconductor laser device is connected with a drive circuit that generates a positive potential, while the n-side electrode thereof is connected with a dc power supply that generates a negative potential.

Semiconductor laser apparatus and optical apparatus

A laser diode package includes a heat sink, a laser diode, and an electrically nonconductive (i.e. insulative) substrate. The laser diode has an emitting surface and a reflective surface opposing the emitting surface. The laser diode further has first and second side surfaces between the emitting and reflective surfaces. The heat sink has an upper surface and a lower surface. The first side surface of the laser diode is attached to the heat sink adjacent to the upper surface. The substrate is attached to the lower surface of the heat sink. The heat sink is made of heat conducting metal such as copper and the substrate is preferably made from gallium arsenide. The substrate is soldered to the heat sink as is the laser diode bar. Due to the presence of the substrate at the lower end of the heat sink, each individual laser diode package has its own electrical isolation. Several packages can be easily attached together to form a laser diode array.

Laser diode packaging

A number of emerging applications of low-temperature co-fired ceramic (LTCC) require embedded fluidic structure within the co-fired ceramic and or precise external dimensional tolerances. These structures enable the control of fluids for cooling, sensing, and biomedical applications, and variations in their geometry from the design can have a significant impact on the overall performance of the devices. One example of this type of application is a multilayer cooler developed recently by the authors for cooling laser diode bars. In many laser systems, laser diodes are the primary emitters, or assemblies of these diode bars are used to pump traditional laser crystals such as Nd:YLF. Assemblies of these diodes require large amounts of electrical current for proper operation, and the device operating temperature must be carefully controlled in order to avoid a shift in the output wavelength. These diodes are packaged into water-cooled assemblies and by their nature dissipate enormous amounts of heat, with waste heat fluxes on the order of 2000 W/cm2. The traditional solution to this problem has been the development of copper multilayer coolers. Assemblies of laser diodes are then formed by stacking these diode bars and coolers. Several problems exist with this approach including the erosion of the copper coolers by the coolant, a requirement for the use of deionized water within the system, and a significant CTE mismatch between the diode bar and the metal cooler. Diodes are bonded to these metal structures and liquid coolant is circulated through the metal layers in order to cool the diode bar. In contrast, the coolers developed by the authors utilize fluid channels and jets formed within LTCC as well as embedded cavity structures to control the flow of a high-velocity liquid and actively cool the laser diode bars mounted on the surface of the LTCC.† The dimensional tolerances of these cooler assemblies and complex shapes that are used to control the fluid can have a significant impact on the overall performance of the laser system. This paper describes the fabrication process used to create the precise channel and jet structures used in these LTCC-based coolers, as well as some of the challenges associated with these processes.

Fabrication of Precise Fluidic Structures in LTCC

A laser diode assembly has a laser diode. The laser diode has an emitting surface and a reflective surface opposing the emitting surface. The laser diode has first and second side surfaces between the emitting and reflective surfaces. A first electrically-insulating heat sink is attached to the first side surface of the laser diode via a first solder bond, and the first heat sink has a first cooling channel. A second electrically-insulating heat sink is attached to the second side surface of the laser diode via a second solder bond, and the second electrically-insulating heat sink has a second cooling channel. A substrate has a top side and a bottom side, and the top side being in communication with a first bottom side of the first electrically-insulating heat sink and a second bottom side of the second electrically-insulating heat sink. The substrate has a flow channel system for passing a coolant to the first cooling channel and the second cooling channel. A metallization layer is attached to the first electrically-insulating heat sink and the second electrically-insulating heat sink. The metallization layer is electrically coupled to the laser diode and conducts electrical current to the laser diode. The metallization layer is isolated from the coolant.

Laser diode package with an internal fluid cooling channel

A laser diode package ( 10 ) according to the present invention is tolerant of short-circuit and open-circuit failures. The laser diode package ( 10 ) includes a laser diode bar ( 12 ), a forward-biased diode ( 14 ), a heat sink ( 18 ), and a lid ( 16 ) which may have fusible links ( 86 ). The laser diode bar ( 12 ) and the forward-biased diode ( 14 ) are electrically connected in parallel between the heat sink ( 18 ) and the lid ( 16 ). The emitting region of the laser diode bar ( 12 ) is aligned to emit radiation away from the forward-biased diode ( 14 ). Several packages can be stacked together to form a laser diode array ( 42 ). The forward-biased diode ( 14 ) allows current to pass through it when an open-circuit failure has occurred in the corresponding laser diode bar ( 12 ), thus preventing an open-circuit failure from completely disabling the array ( 42 ). The fusible links ( 86 ), if used on the lid ( 16 ), prevent damaged active regions ( 90 ) in a laser diode bar ( 12 ) from short-circuiting and drawing more electrical current than the other active regions ( 90 ).

Fault tolerant laser diode package

A laser diode package includes a laser diode, a cooler, and a metallization layer. The laser diode is used for converting electrical energy to optical energy. The cooler receives and routes a coolant from a cooling source via internal channels. The cooler includes a plurality of ceramic sheets and a highly thermally-conductive sheet. The ceramic sheets are fused together and the thermally-conductive sheet is attached to a top ceramic sheet of the plurality of ceramic sheets. The metallization layer has at least a portion on the thermally-conductive sheet. The portion is electrically coupled to the laser diode for conducting the electrical energy to the laser diode.

Edward F. Stephens

Papers

Laser diode packaging

Fabrication of Precise Fluidic Structures in LTCC

Laser diode package with an internal fluid cooling channel

Fault tolerant laser diode package

Microchannel cooler for high efficiency laser diode heat extraction