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Laser trimming adjusts the resistance of chip resistors accurately. The pulsing laser trims chip resistors using laser spot one by one. The resistance increased by one laser spot is called spot-increasing. Small spot-increasing leads to high precision. Spot-increasing is relates to the path of laser trimming. Firstly, the method is introduced that study the influence of laser spot on resistance. Secondly,...
A terahertz (THz) pulse laser with a wavelength of 385 μm is optically pumped by a transverse excited atmospheric CO2 laser based on three-level transition in D2O vapor. The used CO2 laser wavelength is 9.26 μm with an output peak power density of 3.0 MW/cm2. The 385 μm THz pulse signal was observed at different D2O vapor pressures. The energy of the THz pulse is performed...
To satisfy the machining of aspheric optical lenses with complex profile and high accuracy demand, the shaping approach of optical lens for CNC turning is studied in this paper. Interpolation algorithms are proposed to plan the machining locus of aspheric surface. Aspheric surface of optical lenses can be formed through piling up micro cylinders producing by the algorithms. Furthermore, interpolation...
For compensating the chromatic dispersion and the dispersion slope simultaneously, an optimization method is presented to design aperiodic phase-only sampled gratings. To obtain a low insert loss, all sub-gratings with the same reflectivity of 99.9% and the different dispersion values are synthesized using the layer-peeling algorithm. By using the simulated annealing algorithm, an optimal set of the...
The output power of solid pulse laser drops as time increases, theoretical analysis is carried out from gain bandwidth for this kind of phenomenon. The normalization output power analytical model is deduced under homogeneous broadening condition, and numerical calculation and analysis is carried out, the result shows that, the widen of gain bandwidth and gain central frequency drift makes output power...
Spot-splitting phenomenon was observed during the propagation of ring laser beam in Kerr-medium of CS2. With solving nonlinear SchrOdinger equation numerically, the effect of spot-splitting was observed when the input laser beam's power density over 98kw/cm2, which is much lower than the ring laser beam's threshold of spot-splitting, and the split pulses can undergo additional splitting.
The optical frequency domain reflectometry (OFDR) based on tunable narrow linewidth fiber laser is studied, including the relation between beat frequency and the distance of fiber under test (FUT). Experimental results show that the OFDR at long-range measurements, about 150 m, with large full width at half maximum (FWHM). At short range, about 1 m, the FWHM increases to 14 cm.
High-quality nanocrystalline silicon films were fabricated in plasma enhanced chemical vapor deposition system by using a high excitation frequency (40.68 MHz) at low temperatures. It is found that the nanocrystalline Si films with high crystallinity of 89% can be obtained by using SiH4 highly diluted with H2. Furthermore, the area density of the nanocrystalline Si is as high as 4.4×1011/cm2. The...
In the paper, A total of 40 pure or two-mixed textile weaves were prepared and classification of these samples was introduced using near infrared spectroscopy (NIRS), all textile samples are selected among four classes, which are Cotton-Terylene, Cotton-Polyurethane, Cotton and Terylene, according to theirs components. Near infrared diffuse reflectance spectra of the samples were collected, Mahalanobis...
Metal-insulator-semiconductors structures (MIS) with a layer of silicon nanocrystals embedded within two SiO2 layers are fabricated by using plasma enhanced chemical vapor deposition. By using current-voltage (I-V) measurements with different sweep rates, we study the mechanism of electrons and holes charging/discharging characteristic of the MIS structures. Distinct current peaks duo to electrons...
Two-Welding torch counterguard automation welding machine adopts double-optical fiber transmission sensor to detect the vertical tube generatrix double-point of radiator in z-axis direction in order to ensure the precise position of the starting welding point during detecting the workpiece. After controller real-timely collects the keying signal of double-optical fiber sensor through the trigger signal...
A nickel complex constructed by the ligand: imidazole has been synthesized, using solvent evaporation method its single crystal was successfully obtained. Its structure has been determined by means of X-ray single crystal diffraction. Its third-order nonlinear optical property has been studied using Z-scan technique with 20 picosecond (ps) pulses at wavelength 1064 nm. Its molecular second hyperpolarizability...
This paper presents a 2-channel parallel laser diode driver processed by 0.35μm SiGe BiCMOS process. Each channel works at bite rate of 4Gbps. To increase bandwidth a "cross couple" capacitance cancel technology is introduced. An isolation method for parallel amplifier is used to avoid substrate coupling noise brought by the adjacent channel. The test results show the LDD can supply 20~80mA...
There are lots of ions Cr3+ in dichromated gelatin (DCG) after exposure and processing. Since the density distribution of Cr3+ is proportional to the exposure of light, distribution of Cr3+ will be sinusoidal. Meanwhile, the ions or molecules of other materials are distributed uniformly in a certain range around Cr3+. Therefore, the distributions of positive and negative charges will be unequal, and...
A low-loss all solid photonic bandgap fiber (All-solid PBGF) is reported with a minimum transmission loss of 0.97 dB/km at 1.55μm. Its bandgap and mode properties are researched theoretically and experimentally.
A novel dual-wavelength erbium-doped fiber laser is proposed and demonstrated. It uses a linear-cavity resonator scheme containing a 50 cm long photosensitive and polarization maintaining erbium-doped fiber with a uniform fiber Bragg grating written at its end, an optical circulator which is used as the all reflecting mirror, an optical isolator and a wavelength division multiplexing coupler. The...
The effect of the tilted substrate on the lithography patterns in maskless Laser Interference Lithography (MLIL) was numerically and experimentally studied. The experiments showed that the period of interference patterns becomes larger with increasing tilt angles of the substrate, as is in good agreement with theoretical analysis. It was also shown that there is no evident change when the rotational...
A novel all-fiber sensor which can measure temperature and strain simultaneously is presented. The sensor scheme is formed by a fiber Bragg grating and two high-birefringence fiber loop mirrors (HBFLMs). Both HBFLMs act as interrogators with one of them also dependent on both temperature and strain. By monitoring the optical power changes, it is feasible to obtain information that permits simultaneous...
A 10-Gb/s Vertical Cavity Surface Emitting Laser (VCSEL) current driver is designed in SMIC 0.18-μm RF CMOS technology, which will be used in the transmitter of optical interconnect system. High current driving capability as well as agile switching speed is achieved by shunt peaking technique and cascade structure. Under a single 1.8V power supply, the driver delivers a modulation current...
In this paper, a novel timing jitter reduction system is introduced for time distribution in a long fiber. The system can stabilize the optical path by compensating the difference of ninth harmonic phase of mode-locked laser pulses in two routine. In our RF transfer experiment, we have obtained 3.3ps RMS timing jitter of a 100-kilometer fiber link.
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