Very strict requirements need to be met for producing a high-quality single-layer antireflection coating on laser diodes facets, In order to obtain a facet reflectivity of the order of 10-4, the index of refraction and the layer thickness of single-layer coatings have to be controlled for better than ±0.02 and ±2nm. In this paper, a mixed source material composed of Zirconium Oxide(ZrO2) and Titanium dioxide(TiO2), whose index is appropriate to the single-layer antireflective coating for 1.5μm InGaAsP laser diodes is described, A new method to control the index of refraction; and a simple and accurate method to control the thickness of deposited layer as well as a novel measurement method of low residual reflectivity of Si wafer are also proposed. One facet coated LDs is driven and ASE spectra are measured. The center wavelength shifts about 50 nm from 1610 nm to 1560 nm and the ripple in the gain is less than 0.2 dB and the broad-band is about 35 nm when the reflectivity is less than 4×10-4 by single layer.
Semiconductor white sources used for illumination have attracted much attention because of the theoretical high electro-optical efficiency and potential huge application market. However the practical electro-optical efficiency for the white light-emitting diode (LED) is far from the theoretical predict. In this paper we propose a novel white light superluminescent diode (WSLD), which has two active layers, and double-wavelength reflection filter films are coated on the facets of the chip. With this design we can get superluminescent light emission at two peak-gain wavelengths, that is, blue light and green-yellow light, thus producing white light. It is shown that WSLD has much higher electro-optical efficiency and better performance than ordinary white LEDs. This novel WSLD will be a new way to realize high-flux and high-efficiency semiconductor white light source.
Pumping source is the key technology of fiber Raman amplifiers (FRA) which are important for ultra long haul and high bit rate dense wavelength division multiplexing (DWDM) systems. In this paper the research work of the project, "Fiber Raman Laser and Amplifier pumped by Nd3+:YVO4 Solid State Laser", supported by the National High-tech Program (863-program) of China is introduced, in which a novel 14xx nm pump module with fine characteristics of high efficiency, simplicity, compactness and low cost is researched and developed. A compact 1342 nm Nd3+:YVO4 diode pumped solid state laser (DPSSL) module is developed with the total laser power of 655mW and the slope efficiency of 42.6% pumped by a 2W 808nm laser diode (LD). A special C-lens fiber collimator is designed to couple the 1342nm laser beam into a piece of single mode fiber (SMF) and the coupling efficiency of 80% is reached. The specific 14xx nm output laser is generated from a single stage Raman resonator which includes a pair of fiber Bragg gratings and a piece of Germanic-silicate or Phospho-silicate fiber pumped by such DPSSL module. The slope efficiency for conversion from 1342 to 14xx nm radiation is 75% and the laser power is more than 300mW each. Finally, Raman gain experiments are carried out with 100km SMF. 100 nm bandwidth with 10dB on-off Raman gain and 1.1dB gain flatness is achieved by pumped at 1425, 1438, 1455 and 1490nm.
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