It is an important way to effectively improve applied optics experimental teaching effect and motivate the undergraduates’ practice ability and creativity by means of scientific and systematic setting teaching contents and link. Based on the research and analysis of applied optics experiment teaching present condition at home and abroad, this paper aims to solve the existed problems and deficiencies during the experiment teaching in our university, and also puts forward some reform ideas and practice method from several aspects such as teaching thought, teaching content and mode, examination and evaluation and so on. Simultaneously, this paper also gives some suggestions on the future course development.
The traditional experimental teaching methods have some shortcomings in the training the student innovation ability. In order to improve the student practical ability in the photoelectric technology, in this paper new experimental teaching modes are tried and reformed for cultivating the innovative ability of students in the linear CCD experiment. The photoelectric experiment systems are independently designed and completed by students. Compared with the traditional experimental teaching methods, this new methods have a great role in the development of the ability of creative thinking.
With the progress of study on fiber optic gyroscope (FOG), the higher demand for performance of polarization maintaining fiber (PMF), and miniaturization is one of the important development direction. Compared to other stress-induced PMF, the birefringence of elliptical cladding type PMF has small effect when we make stress area smaller, and it can meet the requirements of fiber optic gyroscope. Therefore, 40 microns ultrafine diameter elliptical cladding type polarization maintaining fiber can be the preferred option of the FOG towards light, small, spiritual direction. In this paper, we use finite element method to analysis stress-induced birefringence of 40 microns ultrafine diameter elliptical cladding type PMF, get the stress contours on cross-section of PMF, and calculate the stress birefringence, the polarization mode field distribution and modal birefringence. Under the given simulation conditions, the magnitude of stress birefringence in core is about 10-4, and the magnitude of model birefringence is about 10-4. The results show that 40 microns ultrafine diameter elliptical cladding type PMF has a uniform stress field distribution and a large birefringence. It is conductive to achieve miniaturization of PMF.
A series of LiNbO<sub>3</sub>:Hf:Ce:Cu crystals with various level of Hf doping were prepared using the Cz equipment with a resistance furnace. The crystal storage properties with optical damage resistance ability, sensitivity and dynamic range were measured by means of two-beam coupling light path. The defect structure is also discussed, accounting for the optical damage resistance. Based on optimal one of these crystals as storage medium, one thousand of holograms were recorded in a public coherent volume of 0.073 cm<sup>3</sup>. The result shows that storage density arrives10.7Gbits/cm3 and the crystal has potential application in the future high density storage..
we design a novel core-suspended capillary fiberhat the core is suspened in the air hole and close to the inner surface of the capillary, and experimentally demonstrate its fabrication technology. In addition, a method for linking a single mode fiber and a core-suspended fiber is proposed based on splicing and tapering at the fusion point between the two fibers. By combining with the optical time domain reflectometer technology, we construct a distributed gas sensor system to monitor greenhouse gas based on this novel fiber.
A coaxial dual-waveguide structured optical fiber with an annular waveguide layer (CDOF) is designed and its
preparation method is provided thereof. The responding preform is fabricated by MCVD technique and then is drawn by
a custom-made fiber drawing tower. The optical fiber has a common fiber core and an annular waveguide layer on the
outer surface of the optical fiber. The refractive index profile is measured by a refracted near-field technique and a
standard cutback technique. The fiber can be applied in a novel optical fiber device or an optical fiber sensor, for
example, in-fiber integrated Michelson or Mach-Zehnder interferometer.
Preform rod feeding module is pre-stage module in the system of Optical Fiber Drawing Tower, its stability directly
affects the wire diameter precision of the fiber. For meeting the demand of scientific research to special optical fiber, we
design a new kind of preform rod feeding system, using STM32 as development platform, high-performance actuating
motor as executive device and high precision grating ruler as measurement device. In order to improve the stability of the
system, we adopt the algorithm design of PID closed-loop control. Finally, real-time monitoring and fast response
control of preform rod operation state is realized. The results show that the system runs steadily, and can meet production
requirement of special optical fiber.
A series of Sc:Ce:Cu: LiNbO<sub>3</sub> crystals with various level of Sc doping were prepared using the Cz equipment with a
resistance furnace. The crystal storage properties with optical damage resistance ability, sensitivity and dynamic range
were measured by means of two-beam coupling light path. The defect structure is also discussed, accounting for the
optical damage resistance. Based on optimal one of these crystals as storage medium, one thousand of holograms were
recorded in a public coherent volume of 0.082 cm<sup>3</sup>. The result shows that storage density arrives10 Gbits/cm<sup>3</sup> and the
crystal has potential application in the future high density storage.
Proc. SPIE. 6723, 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
KEYWORDS: Signal to noise ratio, Spectrum analysis, Digital signal processing, Statistical analysis, Doppler effect, Error analysis, Fourier transforms, Computer simulations, Signal processing, Laser Doppler velocimetry
This paper analyzes and compares existing variety of LDV technologies. According to existing LDV's deficiencies such as limited signals processing ability, poor adaptability and low precision, a new design scheme of LDV based on digital signal processing is introduced in this article. Doppler signal processing systems processes the spectrum by DSP. The system consists of a filter, a wave detector, an A/D converter and buffer. DSP system samples digital signals and performs Fourier Transform, and the information of velocity is obtained. To achieve a high signal to noise ratio (SNR), many signal processing techniques are applied, such as inserting zero, signal window, the algorithm of periodic diagrams based on FFT and the algorithm of approaching peak value, all of this highly improve the noise adaptivity. In recent years, the spectrum zooming technology is developed quickly, the algorithm of Zoom-FFT based on complex modulation improves the analysis precision, calculation efficiency, resolution and flexibility effectively. In this paper, the time domain sampled signals are windowed firstly, then the zooming analysis via Zoom-FFT algorithm is implemented, and at last,the energy Centrobaric rectifying algorithm is applied to do further estimation. Simulation results indicated that the algorithm has many merits, such as anti-jamming, high accuracy and a small amount of computation.
A serial of Nd, Zn double-doped LiNbO<sub>3</sub> crystals were grown. The dependence of structure on the concentration of ZnO
was investigated on the basis of analysis of UV-visible absorption spectra and IR transmittance. In addition, the
photoconductivity and the loss of signal-to-noise-ratio coefficient of these as-grown crystals were also measured in terms
of two wave coupling. Finally, one of Nd, Zn:LiNbO<sub>3</sub> crystals was applied to holographic associative memory system,
and excellent output performance was gotten. The results indicate that Zn doping with various concentration in
Nd:LiNbO<sub>3</sub> crystal change the defect structure, especially increase the photoconductivity, and therefore efficiently
suppress the noise generation.
Lithium niobate single crystal has been found to be a versatile material in the field of nonlinear devices due to its
excellent electric-optical, dielectric and nonlinear optical properties. When LiNbO<sub>3</sub> device serves as holographic storage
media, it is often required a big dynamic range, a big sensitivity and a high photo-damage resistance ability. Although
Fe-doped LiNb0<sub>3</sub> in holographic storage is one the most widely investigated crystals and takes on better comprehensive
merits, its performance is severely limited by the low photo-damage resistance ability when LiNbO<sub>3</sub> is operated on high
laser intensity. Indium is one of the beneficial impurity ions for suppressing photo damage. In this paper, we grown a
series of Fe:In:LiNb0<sub>3</sub> crystals with a varying content of In doping by Czochraski technique. On the basis of the
ultraviolet-visible absorption spectra measurement and two-wave coupling experiment, the effect of In ions on
photorefractive properties is explored and discussed systematically. It is found that the photorefractive properties can be
greatly enhanced by In doping in Fe:LiNb0<sub>3</sub>. Among the four samples of Fe:In:LiNbO<sub>3</sub> crystals, the Fe:In(2
mol%):LiNbO<sub>3</sub> crystal has the highest photorefractive sensitivity and the largest dynamic range (1.79 cmJ<sup>-1</sup> and 2.10,
respectively) and can resist higher intensity laser irradiation. Our analysis indicates that increased photoconductivity is
mainly responsible for the excellent photorefractive comprehensive properties. It is believed by the experimental results
that Fe:In(2 mol%):LiNbO<sub>3</sub> crystal is a promising holographic storage medium.
A series of LiNbO<sub>3</sub> crystals doped with different levels of In<sub>2</sub>O<sub>3</sub> were grown by Czochraski method. The photo-damage threshold as well as infrared transmittance spectra and doubling frequency conversion efficient of the crystals was measured. At the same time, the shift mechanism of OH- absorption peaks in In:LiNbO<sub>3</sub> crystals were investigated. In the experiment of frequency doubling, it was found that the phase-matching temperature of In:LINbO<sub>3</sub> crystals was lower than that of Mg:LiNbO<sub>3</sub> and Zn:LiiNbO<sub>3</sub> crystals.
The LiTaO<sub>3</sub> crystal doped with 0.03 wt% Fe<sub>2</sub>O<sub>3</sub> was grown in a diameter-controlled Czochraski equipment using Si-Mo bar heater furnace. The photo-damage resistance ability, exponential gain coefficient, diffraction efficiency and response time of Fe:LiTaO<sub>3</sub> and Fe:LiNbO<sub>3</sub> crystals were measured. The measured results showed that the photo-damage resistance ability of Fe:LiTaO<sub>3</sub> crystal was as much as 5 times higher than that of Fe:LiNbO<sub>3</sub>, the response speed of Fe:LiTaO<sub>3</sub> crystal was improved one order of magnitude than that of Fe:LiNbO<sub>3</sub>, and the exponential gain coefficient and diffraction efficient of Fe:LiTaO<sub>3</sub> crystal were smaller than that of Fe:LiNbO<sub>3</sub>, respectively. Using Fe:LiTaO<sub>3</sub> crystal as recording medium, the obtained image was clear and complete in the holographic associative memory experiment using self-pump phase conjugate reflector.