Papers by Keyword: Semiconductor Lasers

Abstract: 920 nm OPS-VECSEL has an important application in laser display. We constructed and optimized a 920 nm optically pumped semiconductor vertical external-cavity surface emitting laser (OPS-VECSEL) with active region of In0.09Ga0.91As quantum well (QW) system pumped by 808 nm laser diode module. By the finite element method, self-consistent solutions of the semiconductor electronic and optical equations are realized to calculate the characteristics parameters of OPS-VECSEL. The performances of device, especially the mode, the threshold and the optical-optical translation efficiency, were analyzed by dealing with different numbers of QWs (1, 2 and 3) in one period, QW depth, barrier width, the component and dimension of the non-absorption layer. We chose the best structure of them. On this basis, we optimized the external cavity mirrors reflectivity and the simulation showed that the performances would be significantly increased.

Abstract: 920 nm optically pumped semiconductor vertical external-cavity surface emitting laser (OPS-VECSEL) has an important application in laser display. We constructed and optimized a 920 nm OPS-VECSEL with active region of In0.09Ga0.91As quantum well (QW) system pumped by 808 nm laser diode module. By the finite element method, self-consistent solutions of the semiconductor electronic and optical equations are realized to calculate the characteristics parameters of OPS-VECSEL. The performances of device especially the mode, the threshold and the optical-optical translation efficiency were analyzed by dealing with different number of QWs (1, 2 and 3) in one period, QW depth, barrier width, the component and dimension of the non-absorption layer. We chose an improved structure of them. On this basis, we ameliorated the number of QW periods and the simulation showed that in order to obtain high performance device, the choice of the number of QW periods must be cautious.

Abstract: A novel spatial filtering collimator is developed for the laser indication application. The mass produced, inexpensive, red and blue semiconductor laser modulars can easily be optimized as fine line laser indicator source. We have theoretically investigated the results, simulated the designs, and measure the laser beam spots and the laser fine lines. The spatial filtering collimator is designed and optimized for practical used and the results are very satisfactory.

Abstract: The surface brightness values in different directions are different, the measurement of the existing optical gloss meter only once can not simultaneously achieve measurement from different directions, for this phenomenon using orthogonal pairs of optical measurement method, two groups of measurements should be averaged. Measuring probe is made of a 2kHz pulse modulation circuit, silicon photovoltaic cells, I / V conversion, high-pass filter, such as precision rectifier circuit. Measurement probe output signal by the dual analog switch and the ADC into the computer. System software using VB, can realize to show the average computation, numerical analysis and results of statistical functions. Semiconductor laser light source eliminates the need of optical collimating lens. Measurement of laser modulation frequency is 2kHz, much higher than the environmental stray light, using techniques based on frequency domain interference with satisfactory light scattering resisting effect,the test shows that the error caused by stray light is less than 1.5% ,when the instrument works open-ended in the light path.

Abstract: For the influence of the temperature and current, the power of semiconductor laser fluctuates constantly. So this paper comes up with a new method to solve this problem. The design of peripheral circuit contains two parts: temperature control and power control. The system of temperature control uses special laser temperature control chip, which realizes the accuracy of 0.01°C. The system of power control adopts hardware PI control, over-current protection, over-voltage protection, and temperature protection. Temperature compensation is added to the circuit, which realizes the accuracy of 0.01mW.

Abstract: We implement the concept of the distributed electrode, which allows to improve the modal behavior of lasers and to reduce spatial-hole burning effects by preferentially localizing current injection in the center of the structure, hence discriminating the optical mode. We report the first realization of distributed electrode lasers emitting at 808 nm with the measured full width at half maximum (FWHM) angle of the minimal horizontal angle as 3.8° while the maximum continuous-wave output power is up to 4 W and high slope efficiencies as high as 0.95 W/A.

Abstract: In this paper, we report a DFB laser diode with a buried SiO2 grating. Epitaxy lateral overgrowth by metalorganic chemical vapour deposition (MOCVD) is conducted to grow the p-type InP cladding layers in the nano-patterned dielectric grating template. The large refractive index difference between SiO2 and InP results an index coupling coefficient κ of about 250 cm-1. The fabricated DFB laser showed a side mode suppression ratio larger than 45 dB measured. The technology developed can also be used for other applications that require high efficiency grating structure.

Abstract: We report on the development of wide gain InAs/InGaAlAs/InP quantum-dash structure for broadband diode laser and amplifier. Characterizations of this material system have been performed using spectroscopy and microscopy techniques. Gain-guided broad area laser fabricated using this material system exhibits lasing wavelength coverage of up to 76 nm at ~1.64 (m center wavelength from simultaneous multiple confined states lasing at room temperature.

Abstract: One challenge for the realization of electrically drive nano-photonic devices is the formation of metal contacts and passivation. In this paper, we report a novel self-aligned method suitable for the formation of the metal contact and passivation for submicron photonic devices. Two different dielectric materials with high selectivity in wet chemical etching and a wet etching of semiconductor to create an undercut are involved. The whole process is completely compatible with existing compound semiconductor process. As a demonstration of this method, the fabrication and characterization of an InGaAsP/InP submicron-ridge waveguide lasers is presented. The method is extendable to high aspect ratio-submicron ridge waveguide and other device fabrication.