Abstract:
A method for improving the functionality of a semiconductor diode laser having an extended vertical waveguide, wherein the active medium is located closer to the top cladding layer of the waveguide. The vertical optical modes of the laser include at least one vertical optical mode extended over the entire extended vertical waveguide and at least one vertical optical mode localized at the active medium. The goal of using a laser with an extended vertical waveguide is to obtain lasing in narrow beams with high brightness and/or wavelength stabilized lasing. In both cases lasing in a localized mode is highly undesirable due to the resulting reduced brightness of the device and disadvantages related to the catastrophic optical damage of the mirrors of the facet for the localized mode and needs to be suppressed. Several methods of configuring the tilted wave laser in the longitudinal direction are disclosed. In one embodiment the resonator length (in the longitudinal direction) is specifically selected to be equal to the length of the return path of the tilted wave multiplied by a rational number such that the tilted wave in the extended vertical waveguide forms a closed loop. In this embodiment, the lasing from the narrow waveguide, in which the active medium is located, is suppressed.
Abstract:
A semiconductor diode laser having a broad vertical waveguide and a broad lateral waveguide is disclosed emitting laser light in a single vertical mode and a single lateral mode narrow beam. The vertical waveguide comprises a coupled cavity structure, wherein light, generated in the active medium placed in the first cavity leaks into the second cavity and returns back. Phase matching conditions govern the selection of a single vertical mode. A multi-stripe lateral waveguide comprises preferably a lateral photonic band crystal with a lateral optical defect created by selected pumping of multistripes. This approach allows the selection of a single lateral mode having a higher optical confinement factor and/or a lower absorption loss and/or a lower leakage loss compared to the rest lateral optical modes. This enables a single lateral mode lasing from a broad area field coupled laser array. A laser system comprised of multiple field coupled laser arrays on a single wafer and a set of external mirrors enables an ultra-broad field coupled laser bar emitting a coherent laser light in a single vertical optical mode and a single lateral optical mode. A laser system comprised of multiple ultra-broad field coupled laser bars on different wafers and a set of external mirrors enables an ultra-broad field coupled laser stack emitting coherent laser light in a single vertical optical mode and a single lateral optical mode. This allows realization of ultrahigh power ultrahigh brightness laser systems based on semiconductor diode lasers.
Abstract:
A method for the hybrid integration of vertical cavity surface emitting lasers (VCSELs) and/or other optical device components with silicon-based integrated circuits, based on a series of attachment steps, is described. The method is applicable when a multitude of individual VCSELs or optical devices are processed on the surface of a compound semiconductor wafer and then transferred to a silicon-based integrated circuit. The technique is realized by employing a specific sacrificial or removable separation layer between the optical components and the mother semiconductor substrate, followed by the transfer of the optical components to a carrier substrate, and the subsequent elimination of the sacrificial or separation layer and simultaneous removal of the mother substrate. This procedure is followed by the attachment and interconnection of the optical components to the surface of, or embedded within the upper layers of, an integrated circuit, followed by the release of the components from the carrier substrate. The distinction of this method is the ability to place and interconnect VCSELs directly within the physical structure of the integrated circuit, thus greatly reducing the power requirements, the distance of interconnecting lines, and the resultant operational speed. Selected variations of the method are proposed including the selective placement of groups of physically-connected VCSELs, and the collection and placement of large numbers of fabricated VCSELs onto foreign substrates using a vacuum plating tool.
Abstract:
A selective reflector, for selectively preventing reflection of light passing therethrough. The selective reflector comprising at least one layer characterized by an angle-dependent reflectivity function. The angle-dependent reflectivity function being decreasing upon at least one interval of increasing impinging angle of the light on a surface of the at least one layer, such that when said impinging angle is within a predetermined range, the reflection of light is substantially prevented.
Abstract:
A vertically integrated optoelectronic device allows high- speed data transfer by direct or indirect modulation of the intensity of the emitted light. The device comprises at least one multilayer interference reflector and at least one cavity. In one embodiment the reflector operates as a modulator element controlled by an applied voltage. The stopband edge of the reflector is electrooptically tuned using the quantum confined Stark effect in the vicinity of the cavity mode, resulting in a modulated transmittance of the reflector and, thus, in indirect modulation of light intensity. In another embodiment, the optical field profile in the cavity is affected by the shift of the stopband wavelength, and the device operates as a wavelength- tunable light emitter. In yet another embodiment, two or more refractive index periodicities are integrated in the reflector, suppressing parasitic optical modes and enabling a high-speed direct modulation of the intensity of light emitted by the device.
Abstract:
A light emitting device emits light from the surface in a broad spectral range and a broad range of angles tilted with respect to the direction normal to the exit surface. An apparatus for generating wavelength-stabilized light is formed of a light-emitting device, an external cavity and at least one external mirror. Light emitted by the light-emitting device at a certain preselected angle, propagates through the external cavity, impinges on the external mirror and is reflected back. Reflected light undergoes interference with the emitted light. The interference can be constructive or destructive. Constructive interference results in a positive feedback. The positive feedback conditions are met at one or a few selected wavelengths within the luminescence spectrum of the active region. Then the apparatus generates wavelength- stabilized light. An apparatus may operate as a wavelength- stabilized light-emitting diode, a wavelength- stabilized superluminescent light-emitting diode, or a wavelength-stabilized laser, or an apparatus for frequency conversion.
Abstract:
Apparatus (Figure 3, Character 10) for frequency conversion of light, the apparatus comprises: a light-emitting device (Figure 3, Character 201) for emitting a light having a first frequency, the light-emitting device (Figure 3, Character 201) being an edge-emitting semiconductor light-emitting diode having an extended waveguide (Figure 3, Character 204) selected such that a fundamental transverse mode of the extended waveguide (Figure 3, Character 204) is characterized by a low beam divergence. The apparatus (Figure 3, Character 10) further comprises a light-reflector (Figure 3, Character 214), constructed and designed so that the light passes a plurality of times through an external cavity (Figure 3, Character 212), defined between the light-emitting device and the light-reflector, and provides a feedback for generating a laser light having the first frequency. The apparatus (Figure 3, Character 10) further comprises a non-linear optical crystal (Figure 3, Character 213), positioned in the external cavity (Figure 3, Character 212) and selected so that when the laser light having the first frequency passes a plurality of times through the non-linear optical crystal (Figure 3, Character 213), the first frequency is converted to a second frequency being different from the first frequency.