The polarization mode dispersion (PMD) in a single mode fiber caused by eccentricity of refractive index distribution of core and clad is analyzes and calculates considering that arbitrary uncircularity is equivalent to the ellipse. The relative curves of the difference of propagation constants Δ β and PMD versus the ratio of eccentricity, wavelength, radius of core and difference of refractive index are obtained. It can offer a theoretic guidance for decreasing the PMD in a single mode fiber. The PMD caused by eccentricity has the same magnitude with that caused by ellipticity.

new type of rapid electro optic scanner of narrow laser beam is studied. The operation principle of the developed scanning device and the effect of the device structure on the scanning characteristics are analyzed theoretically. The experiment shows that the two dimensional rapid scanning with wide viewing field of narrow laser beam can be realized by the device with very small control voltage (<10 V)

The two fiber gratings with two different wavelengths in a single mode fiber are bonded to the two neighboring side faces near the fixed end along the axial direction of a cantilever beam. Using the characteristics of fiber grating encoding, we have realized the measurement of the two dimensions for the stress or the displacement. The theoretical analyses and the experimental results indicate that the magnitudes and the directions of the stress, displacement and other mechanical quantities can be sensed and measured in real time through monitoring the value and direction of the wavelength shift of the two fiber gratings that are bonded to the near fixed end of the cantilever beam. In the vertical directions of the cantilever beam axis, the experimental sensitivities of the stress are 5.32 nm/N and 3.21 nm/N, the experimental sensitivities of the displacement are 0.30 nm/mm and 0.48 nm/mm, respectively.

A new method for long focal length measurement is presented, which is accomplished by obtaining the angle of moiré stripe formed by Talbot effect of Ronchi grating. The formula of calculating the long focal length from the angle of Moiré stripe is derived. Error analysis demonstrates that this method can be applied to the real time testing with high accuracy.

A novel method for automatic gain control of optical amplifiers is presented. It uses a F P filter with 26.7 nm free spectral span and two long period gratings (LPGs) for oscillating dual lasers in a single feedback loop. By bending the LPGs, the cavity losses at different wavelengths are varied individually and the dual lasers feedback are varied too. The technique significantly reduces surviving channel steady state and transient power excursion by automatic reduction of relaxation oscillations and spectral hole burning. Properties of this novel optical gain control EDFA with dual control lasers were studied in detail.

The effects of several factors on the gain spectrum of a Raman fiber amplifier (RFA) are discussed. Pump evaluation is discribed by computer simulation with four pump laser diodes. Two methods are used to flaten the gain spectrum, gain flaterfilter (GFF) and pump distribution, and it is found that the pump distribution is better than GFF.

The correct orthogonality relation for optical fiber is applied to the perturbed coupled mode theory, and the corresponding coupled mode equations for common optical fiber are introduced. Its application to fiber Bragg gratings is discussed. The coupling coefficients of the equations for fiber Bragg gratings, being the distinguished feature for coupled mode theories, are different from other theories′. The solutions of the equations are discussed, and the simple formula between the peak reflectivity and the Bragg wavelength, the length of the fiber Bragg grating is obtained. An experiment of fiber Bragg gatings is completed. The peak reflectivity of the experiment is about 0.993, and the corresponding theoretical result is 0.999. The experimental result coincides with the theory very well.

A new experimental method for measuring resonant frequencies of objects is proposed by use of rotating aperture stroboscopic speckle photographic method. It can easily measure the resonant frequencies of objects with this method. In addition to the advantages of high precision, a better visibility of lines is provided. The theoretical analysis and experimental result are given.

Gray scale joint image similarity degree is defined according to the morphology method. Two kinds of modified morphological correlation algorithm based on bit representation decomposition are presented. The gray scale image is decomposed into a set of binary slices in the bit representation decomposition. In the first algorithm, the edge of each pair of slices is detected. In the second algorithm, the joint power spectrum of each pair is summed after binarized or the summation of the joint power spectrum of these pairs is binarized. Computer simulation results indicate that the modified algorithms can improve the discrimination capabilities with respect to the high similarity gray scale images.

The subdivision principles of linear CCD and area CCD are described. A new subdivision method of area CCD using surface fitting with nine points in four lines is proposed and this new method has been put into actual application for image enlargement and target location. It has been proved that, using the new subdividing method, the calculation is simplified, the higher relativity and good edge trend are reserved, and the image resolution and target locating precision are improved greatly.

A new method is proposed to measure the output states of polarization of single mode fiber with a polarizer and an optical spectrum analyzer, the differential group delay (DGD) of polarization mode dispersion (PMD) can be acquired. Comparing with previous methods, this new method saves measure time, and decreases the error come from variation of PMD with time, so it can improve the precision of measuring.

The second order PMD effect on Gaussian pulse propagation in single mode optical fiber is studied. The explicit expression of second order PMD induced pulse distortions is given in the time domain. It is found that the output pulse in each basic state of polarization retains Gaussian shape but some characters such as the frequency chirp and the pulse width have changed. The relationship between these changes and second order PMD is analyzed. The second order PMD influences in 10 Gbit/s and 40 Gbit/s systems are compared. It is found that the tolerable value of second order PMD in 40 Gbit/s systems is one order of magnitude lower than in 10 Gbit/s systems if the pulse broadening must not exceed one tenth of the pulsewidth.

Complete mean refractive index compensation should include apodization and sampling compensation. However, numerical simulations show that only apodization compensating is required. A simple compensation technique is proposed and demonstrated. Receding the fiber outside the coherent zone, apodization compensation is implemented by controlling the exposure position and exposing time of argon ion laser. The side lobes of reflection spectrum is suppressed. Group delay ripple is smoothed.

A tunable ytterbium doped double cladding fiber laser with high efficiency has been investigated. The output power of the fiber laser was about 440 mW using 1 W 915 nm LD pumping and the slope efficiency was about 80%. The M 2 factor of the output beam in both directions were 1.06 and 1.04, respectively. The output wavelength can be tuned from 1070 nm～1150 nm while using a grating at output coupler.

By means of transfer matrix method, the normal coupled modes of one dimensional photonic crystal with dispersive media are discussed. The dispersive media are described by a Lorentz oscillator model. The complex effective index of the structure is calculated. It is found that the threshold intensity of nonlinear bistability of the one dimensional photonic crystal with dispersive media is much lower than that without dispersive media.

The effects of loading resistor on the self deflection of screening, photovoltaic and screening-photovoltaic solitons are investigated by use of the universal theory of steady state one dimension photorefractive spatial soliton . Results show that the three kinds of soliton with or without a loading resistor have a similar character in self deflection, i.e., the solitary beam center moves on a parabolic trajectory. The bending distance of these solitons can be adjusted by changing the resistance of the loading resistor. The bending range of bright SP solitons can be adjusted more broadly than those of the other two.

A novel sensing structure is proposed based on fiber Sagnac loop, and all fiber sensing for multi disturbance is realized. The sensing structure has the novel double Sagnac loop and WDM technology instead of traditional double light source, reducing the system error and realizing the measurement of multi disturbance. The analysis of sensing theory, deducing mathematical model and the simple and multi disturbance test are performed. The theory is proved experimently. Analysis indicates that the error is related to frequence response of demodulation circuit.

Au Au 2S nanoshell consists of a nanometer scale Au 2S dielectric core coated with a thin Au shell. The new electromagnetic resonant cavity properties of the gold nanoshell are discussed. The gold nanoshell is regarded as a nanometer electromagnetic resonant cavity, and the cavity resonance displays tunability controlled by the radii of the dielectric core. The main mode of nanocavity resonant absorption is obtained, it shows red shift during the reaction of the gold nanoshells. The parameters of gold nanoshell cavity resonance such as resonant wavelength, energy and linewidth are discussed.

The optical transfer function (OTF) of an optical system with partially coherent illumination was developed according to the theory of image formation. This function is the same as the incoherent OTF of optical system. So the permissible tolerances of the wave aberrations of optical system are identical for illumination either incoherent or partially coherent. This conclusion explained the customary rule of optical system design of microscope that the tolerances of wave aberrations are the same for both the incoherent and partially coherent illumination, no difference for various forms of illumination.

Binary optical elements have many applications. One of the principal limitations of these lenses is abundant chromatic aberration that prohibits broadband use without design compensation. A novel configuration is presented that exploits this typically unwanted effect to create a hyperspectral imager. Diffractive lens′ focal length is inversely proportional to wavelength. The change in the focal length changes the F number of the system and therefore the magnification changes as a function of wavelength. The magnification is different for each wavelength in the recorded spectra, which creates image registration error, and provides inaccurate relative spectral signal strength. In result, the precision of object image reconstruction algorithms is restricted. To compensate for this shortcoming, the optical system with a zoom lens is designed by means of optical two component. The problem is solved successfully in theory. The theoretical formulas are provided.

The phase anomaly zones are investigated on the basis of the integral theorem of Helmholtz and Kirchhoff in terms of the Kirchhoff′s boundary conditions and the physical meaning of the integral for the diverging and converging spherical waves. For the diverging spherical wave, the phase anomaly zone exists in the source space, the phase variations is different in the different parts of the zone, and the point source is a special point of the zone. On the other hand, the phase anomaly zone is in the image space, the phase variation is consistent in all the zones, and the focus is a special point of the phase anomaly zone for the converging spherical wave.

Differential optical absorption spectroscopy(DOAS) has become a widely used method to measure trace gases in the atmosphere. Their concentrations are retrieved by a numerical analysis of the atmospheric absorption spectra. But in the process of application, it is found the error is a bit larger and results are not steady since the limited bandwidth for each analysis subject to system hardware. A new procedure was developed, based on the Madaline artificial neural network theory to expand the spectra bandwidth. A good result was obtaind with this method according to the comparison of the different test results.

The relationships between the recording properties and the recording laser power and pulse width of the Ag 5In 5Sb 47 Te 33 thin films were investigated and the recording domains morphology was observed. The results showed that the recording domains could be obtained when the recording laser power and pulse width were within a certain range, and the morphology of the recording domains is very clear and is amorphous Ag 5In 5Sb 47 Te 33 . When the laser power and pulse width could not provide efficient energy to induce significant change in the films, the morphology of the recording domains is very illegible. When the ablation took place the recording domains were composed of the ablation area and the surrounding amorphous Ag 5In 5Sb 47 Te 33 . In addition, the optimum recording conditions (12 mW recording power and the 90 ns laser pulse width) were obtained, the reflectivity contrast of the recording domains obtained under the condition is 22% and the domain diameter is 380 nm～400 nm.

Several bormo substituted copper phthalocyanine derivatives: monbromo tetraalkoxyl phthalocyanine copper, dibromo tetraalkoxyl phthalocyanine copper, tetrabromo tetraalkoxyl phthalocyanine copper and tetraalkoxyl phthalocyanine copper thin films were prepared on single crystal silicon substrates by spin coating respectively. The ellipsometric spectra of these films have been investigated by using an improved rotating analyser polarizer (RAP) type of scanning ellipsometer. The refractive indices and absorption coefficients of the films were given in the wavelength range 500 nm～800 nm. Effects of peripheral electron withdrawing bromine substitute on the optical properties of the thin films were studied as well.

The influences of the substrate temperature and post deposition annealing in an Ar gas flow on the transmission, reflection and absorption spectra, optical constants and carrier concentration of CdIn 2O 4 thin films, which was deposited by r.f reactive sputtering from a Cd In alloy target, are discussed. It shows that carrier concentration decreases when substrate temperature is increased, and concentration will increase after thin film is subjected to annealing. The peaks of refractive index n and extinction coefficient k undergo blue shift with increasing substrate temperature, and red shift occurs after thin film is annealed. This is in good agreement with the change of carrier concentration. It is of significance to monitoring in situ the film process in the course of deposition of the transparent conducting thin films such as CdIn 2O 4 which are sensitive to deposition methods and deposition conditions.

Several amorphic carbon films with different thickness were deposited on single crystal silicon by means of pulse laser ablating graphet target at room temprature. Morphology was observed with scanning electron microscope (SEM). Raman scattering spectroscopy and Fourier transform infrared spectroscopy (FTIR) were analysised. It is found that these films had little of graphet micro crystaline in their matrix. A Raman peak for amorphic diamond was found around 1200 cm -1 . These films were transparent in infrared and suit for antireflective film deposited on silicon in the range of wavelength short than 8 μm.

The thin films were fabricated by varying the magnetron sputtering power in order to investigate the influence of the sputtering power on the structure of thin films. The results show that the thin film deposited at very low power has the distorted XRD charateristic peaks with low intensity and the large width of half peak, while the films deposited at high power show the sharp characteristic peak. The related investigations illustrate that the thin film deposited with low power has the loose structure, and that with high power has coherent structure.

The quantitative theory of optimum doping content of transparent conductive films was introduced. In this theory, the relationship of one of the physical properties with crystal structure, preparation method and doping content was set up. The parabola equation that can be fixed to the test curve and has reliable physical meaning was given. The extreme value of this equation just determined the quantitative relationship between the optimum doping content, crystal structure and preparation method, and the expression of the optimum doping content was obtained accordingly. The experimental results of doping modified for WO 3 electrochromic films were analyzed. Using this expression to calculate the optimum doping content in WO 3 electrochromic films, the quantitative calculation results are in accordance with the experimental results. This theory is also appropriate for the optimum doping content problems of other materials.