<p>Photoelectric functional material WS<sub>2</sub> thin film on SiC substrate was synthesized. Both 15 and 150 nm thickness of WS<sub>2</sub> film were deposited on an n-doped SiC substrate (7.37 × 10<sup>19</sup> cm<sup> − 3</sup>) by pulsed laser deposition method. Optical properties of the WS<sub>2</sub> / SiC material were discovered. (I) a photovoltaic effect: (1) there is a cutoff wavelength λ<sub>c</sub> (661 nm), which means the wavelength of an incident monochromatic light must be less than λ<sub>c</sub> in order to have the photovoltaic effect; (2) the incident light must be polarized. (3) It was found that the maximum open circuit voltage output is 6.3 V in a condition of 40 mW @ 532 nm. (II) Wavelength blueshift: when a laser of 532 nm is used in the experiment to incident perpendicularly through the thin layer WS<sub>2</sub> / SiC film stack, which is driven by an external electric field, it is found that the 532-nm photons are blueshifted 1.33 nm under a 30 V (DC) voltage. We also find that the blueshift of the laser wavelength is tunable with the applied voltage. Inverse Compton scattering of the photon by both electron and hole is used to explain this blueshift, the consistency of experimental results and the theoretical calculation for the wavelength blueshift was found.</p>
An optical material WS<sub>2</sub> thin film on SiC substrate was synthesized. Both 15nm and 150nm thickness of WS<sup>2</sup> films were deposited on a n-doped SiC substrate by pulsed laser deposition (PLD) method. Tungsten disulfide films were superimposed face to face, and silicon carbide was used as the electrode to apply an electric field ranging from 0V/nm to 0.18v /nm. The experimental results showed that band gap were continuously tunable from 2.017ev to 1.507ev. The first principle calculation by using Quantum Espresso also was performed to simulate the band gap change with the increase of an external electric field. It is found that the band gap of WS2/SiC film changes from 1.973ev to 1.488ev as an electric field applied perpendicularly to the film ranging from 0V/nm to 0.18v /nm. The consistency of experimental results and the first principle calculation was found.
Highly uniform solid-phase Zn-diffusion technique was developed to fabricate transparent windows for 650 nm red laser diodes (LDs). The maximum output power was up to 120 mW, which is three times higher than that for LDs without window structure. The LDs showed excellent thermal characteristics and aging reliability with TO-can package. The characteristic temperature was estimated to be 85 K in the temperature range of 25~65 °C. The LDs showed stable operation of 10 mW at a high temperature of 75 °C. After aging test of 2000 h, the elevated operation current was less than 3%, compared to the initial value. The predicted life time was over 10000 h for 10 mW operation at 75 °C.
In this paper, we present a high power TM Polarized GaAsP laser diode of 808nm wavelength. For high power and narrow beam divergence, an asymmetry broad waveguide structure and a tensile strained GaAsP quantum well were used and the epilayers were grown by low-pressure metalorganic chemical vapor deposition. We have obtained an optical power of 20.86W at 20A without COMD and the vertical farfield of 27°. It is expected that Al-free GaAsP quantum well laser diodes will have good reliability
without any facet treatment.
With the support of state key project, Shandong Huaguang Optoelectronics Co. Ltd. realizes the mass production of low threshold current 650nm GaInP/AlGaInP semiconductor laser chips, rapidly. At present, six million 650nm LD chips can be produced per month. The lowest threshold current at 25°C is 7.4mA. The slope efficiency reaches 1.1mW/mA and the output power is 34mW at 40mA CW operation.
A continue-wave (CW) laser-diode (LD) pumped passively Q-switched intracavity frequency-doubling green laser is reported in this paper. We used 3%at. Nd doped YVO4 with size of 3 X 3 X 1mm as gain medium, Cr4+:YAG as a saturable absorber with small-signal transmission T0=94% for passively Q-switch and periodically poled LiNbO3 (PPLN) with the grating period ? =6. 1 µm as a frequency doubler. The laser cavity was consisted of one face of the Nd:YVO4, coated high-reflectance (HR) coating at 1.06 µm and high transmittance (HT) at 0.808 µ m, and a 50mm radius of curvature output mirror with HR coating at 1.06 1 µm and HT coating at 0.53 µm.. A CW 1W LD and a grading-refractive-index lens were used for the end-pumping. The output energy of the green laser is 0.96 µ J with the pulse-width of 19ns. No green-noise problem exists in the green laser, because both the polarizations of fundamental wave and second harmonic wave are the same. Some theoretical results on the passively Q-switching and intracavity frequency-doubling are also reported.