Abstract Ridge-type 1.3£gm InGaAsP diode lasers with planar waveguide structure have beem successfully fabricated and mounted on silicon submounds. The laser diodes were fabricated by first etch a ridge structure for light guidance.Typical ridge width is around 3£gm. After ridge etching, a SiO2 thin film was sputtered onto the sample as surface passivation layer, fllowing by the coating of Benzocyclobutene (BCB) polymer for surface planarization.The unwanted BCB polymer was removed by dry etching process until the passivation oxide can be observed.Before metallization, SiO2 layers above the ridge were removed by wet etching technique. The fabrication was completed by evaporating contact metals to the samples. The finished samples were cleaved into laser dies with a dimension of 500£gm¡Ñ300£gm.The dies were mounted onto a Si submound for DC and AC measurement.The threshold current of the planarized laser is 34mA.The threshold voltage and total resistance of the planar device are 1.31V and 10.1£[.The quantum efficiency as large as 76¢H is obtained.The frequency response of the device is also measured.The 3dB bandwidth is about 1.9GHz¡C

Abstract As blue/green laser has a short wavelength radiation, it can be applied to micro-machining, laser display, high-density optical data storage, underwater communications, and so on. Large efforts have been devoted to simplify the laser system and reduce the cost. Therefore, various types of blue/green lasers have been studied, especially intracavity frequency doubling of the diode-pumped solid-state laser, which can effectively generate high blue/green laser powers with long lifetime. Among all cavity designs, direct-coated composite crystal is the most compact structure. Compare with the green laser, which is a four-level laser, blue laser belongs to a quasi-three-level system. Thus, it is more important to control the temperature of gain medium. Before the experiment, making an estimation will greatly benefit the progress and efficiency. ZEMAX was utilized to simulate the focus system and GLAD was used to model our intracavity frequency-doubled blue laser. In the experiment, we used a LD array as a pumping source and arranged suitable lens to reduce the array¡¦s spot size. The laser crystal was mounted onto a copper mount which was cooled by the Vapochill cooling system. In addition, we also tried to rotate the crystal and obtained a peak power of 192 mW with only 4 mm cavity length. The result is the highest output power of microchip blue laser to our knowledge. Using lens duct as the pump transport optics can further miniaturize this composite-chip blue laser.

The rapid developments in optical and electronic technologies have accelerated developments of solid state laser technology. The diode-pumped solid state laser has the merits of the diode laser, such as compactness, low cost, and the merits of the solid state laser, such as high laser quality, high conversion efficiency, long lifetime, and simple structure. There use in laser applications is very cost-effective in terms of material consumption, which is typically one-thousandth that of bulk material. In addition, heat dissipation in the gain medium can be significantly alleviated because highly heat-conductive material can be applied to the circumference of the crystal fiber. So, it was applicated in electronics, communication and medicine widely. The laser-heated pedestal growth (LHPG) method is now a well-established technique for the growth of single-crystal fibers. It is crucible free and can therefore produce high-purity, low-defect-density single crystals. Interface loss is one of the dominant factors that reduce the efficiency of crystal fiber lasers, although cladding with a dielectric coating or in-diffusion of the gain core has been utilized to suppress this interface loss. Using a gradient-index Nd:YAG crystal fiber with peak Nd concentration up to 1.6-atm.%, we recently demonstrated a laser power of 145 mW and slope efficiency 28.9%. Peak Nd concentration up to 3.6-atm.% Nd:YAG crystal fiber with a 20-um core was grown, which could eliminate the interface loss and enhance the efficiency of crystal fiber lasers to be compatible with bulk solid-state lasers.

The goal of this paper is to study the mechanism that may lead to the change of physic properties by annealed amorphous AZO samples, that were grown by RF magnetron sputtering, by an excimer laser or a tube furnace or both. By using of the Taguchi Methods, which is in expected to be a fast and efficiency method, to search the best process parameters and to understand what mechanism stood behind the change of these parameters. We found that polycrystalline AZO films may be formed very easily when were grown at a temperature higher than 150K. Amorphous AZO films may grow successfully only at low growth temperature, ~77K. Annealing in tube furnace can alter the crystalline properties. Recrystalization starts at 325oC. Laser annealing will also recrystalize the amorphous AZO films with laser energy density higher than 160mj/cm2. Unfortunately, neither method provide enough improvement in the electric conductivity.

In this paper, a ring laser design based on tapered waveguide coupler is fabricated and discussed. Using the asymmetric tapered waveguide coupler, two different directional coupling can be realized. Such that, the spatial-hole burning problem in linear laser cavity can be avoided, leading to the possibility of unidirectional traveling laser. In the work, two types of ring laser structures are fabricated and analyzed, in which (1) 90 degrees total reflection mirrors (TIMs) and (2) circular retro-mirrors are defined. Through the current injection on the tapered waveguide coupler, the received spontaneous emissions power at different directions (clockwise and counterclockwise directions) shows a 3dB difference for both type (1) and (2). Two oscillations in ring resonator could give different round-trip loss, indicating the possibility to fabricate unidirectional ring laser.

Thèse de doctorat : sciences. Génie des matériaux : Ecully, Ecole centrale de Lyon : 2005. / 62 réf.

Thèse de doctorat : sciences. Génie des matériaux : Ecully, Ecole centrale de Lyon : 2005. / Titre provenant de l'écran-titre. 62 réf.

Reproductin de : Thèse de doctorat : Physique : Lyon 1 : 2005. / Titre provenant de l'écran titre. Bibliogr. en fin de chapitres.

Reproduction de : Thèse de doctorat : Génie des procédés et de l'environnement : Toulouse, INPT : 2006. / Titre provenant de l'écran-titre. Bibliogr. 126 réf.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.