A simple and new system for measuring the diffraction efficiency of large aperture gratings at littrow angle is
established in this paper. The reference grating Po, double beams and timer with shutter have been draw into the
system for eliminating the impact of polarization and stray light, fluctuation of incident light, and the fatigue of
photodetector. A program is designed to scan, measure and calculate the diffraction efficiency of the gratings
automatically. The diffraction efficiency accuracy measured for the gratings is increased by ~1% with this system. To
achieve more measured accuracy, additional beam of reflection light should be imported.
The uniformity of ion beam current density profile has been amended by changing the flow of the gas and making a new
beam channel. The platform scanned in the horizontal orientation in this experiment, so the horizontal ion beam current
distribution had hardly any effect on the etching uniformity and amending the ion beam current density profile in the
vertical orientation was sufficient for the purpose of plat etching profile. The ratio of the ion source's working gas inputs
has some effect for the uniformity and a ratio of 6.50sccm: 8.00sccm: 9.60sccm of the three gas inputs flow1: flow2:
flow3 will lead to a more uniform profile. According to the horizontal distribution and the original vertical ion beam
current density distribution measured by Faraday Cup, a new beam channel was made. The uniformity of ion beam
current density profile is enhanced from ±4.31%to ±1.96% in this experiment.
A radio-over-fiber (ROF) system that combines a wireless link and an optical fiber link is studied. After introducing the configuration and analyzing the nonlinear distortion of the system, the Volterra series is proposed and used to model the system. The adaptive least mean square (LMS) and recursive least squares (RLS) algorithms for identifying the Volterra kernel are studied. A simulation is given, which uses both Volterra LMS and Volterra RLS to model a nonlinear ROF system, and indicates that the method is efficient.
The regenerative wavelength conversion of the picosecond short pulse with repetition rate of 10GHz is demonstrated employing a SOA based interferometer. Both up-conversion and down-conversion can be realized with wavelength range from 1535nm to 1555nm. The regenerative capability of this wavelength convertor is also demonstrated with degradated signal.
We experimentally demonstrate the generation of supercontinuum (SC) with a 12.5GHz DFB/EAM ultrashort optical pulse broadened in the high nonlinear fiber (HNLF). Through longitudinal mode-carving of the SC spectrum, a novel multiwavelength continuous wave (CW) optical source with precise 25GHz channel spacing is realized. The bit error rate (BER) curve and eye diagram show that the multiwavelength CW optical source is promising for dense wavelength division multiplexing (DWDM) systems.