Temperature-dependent Sellmeier equations are useful for determining optical-design parameters of nonlinear optical devices. These coefficients as a function of temperature are calculated for three chalcopyrite crysta...
详细信息
Temperature-dependent Sellmeier equations are useful for determining optical-design parameters of nonlinear optical devices. These coefficients as a function of temperature are calculated for three chalcopyrite crystals: ZnGeP 2 , CdGeP 2 , and CuGaS 2 . Coherence lengths for second harmonic generation as well as its temperature derivative are also presented for these crystals.
A method for calculating the response of a photoelectric scanning Fabry-Perot interferometer to an asymmetric collision- and Doppler-broadened atomic spectral line is presented. The computed profile can also represent...
详细信息
A method for calculating the response of a photoelectric scanning Fabry-Perot interferometer to an asymmetric collision- and Doppler-broadened atomic spectral line is presented. The computed profile can also represent the asymmetry due to coma in an echelle spectrometer. These results allow simple deconvolution of instrumental and source effects.
This paper describes a method for calculating the impulse response and bandwidth of multimode optical fibers from measured refractive-index profiles obtained either from the fiber itself or from its preform. The compu...
详细信息
This paper describes a method for calculating the impulse response and bandwidth of multimode optical fibers from measured refractive-index profiles obtained either from the fiber itself or from its preform. The computational method is based on the WKB solution of the guided-mode problem. First, the pulse delay time of each mode is calculated. The different arrival times of impulses carried by the modes are then used to construct the shape of the impulse response curve whose Fourier transform may be used to predict the signal bandwidth of the multimode fiber. By omitting mode groups or weighting the power distribution among the modes, the influence of certain mode groups on pulse distortion can be studied separately. Dispersion of the host material and of one dopant can be taken into account. The method has been used to study the effects of deviations from the desired perfect index profile and the influence of a central dip. The practical value of the computer program is its ability to predict fiber performance from index measurements made on preforms even before the fiber is drawn.
The indicatrices of solar radiation reflected from characteristic natural surfaces were measured with a Nimbus Medium Resolution Radiometer (MRIR) 3 m above the ground. Results indicated that areas such as salt and al...
详细信息
The indicatrices of solar radiation reflected from characteristic natural surfaces were measured with a Nimbus Medium Resolution Radiometer (MRIR) 3 m above the ground. Results indicated that areas such as salt and alkali flats had only small deviations from isotropic reflections, while others such as sparsely vegetated areas had substantial deviations. The indicatrices were strongly dependent on the sun angle; thus a daily variation was found for most features. Typical indicatrices, normalized to nadir angle of zero degrees, are presented along with their impacts on measured albedo, which varies with solar angle. Our results can (1) improve surface albedo considerations using space-generated data, and (2) serve as a more realistic lower boundary condition for atmospheric transfer determinations based on space data.
For spectral lines with combined Doppler and pressure broadening, the Fourier transform of the line shape is calculated analytically in an isothermal layer in which both the pressure and absorber concentrations vary a...
详细信息
For spectral lines with combined Doppler and pressure broadening, the Fourier transform of the line shape is calculated analytically in an isothermal layer in which both the pressure and absorber concentrations vary along the line of sight. Use of the Cooley-Tukey fast Fourier transform algorithm allows efficient computation of the optical depth of such layers containing a large number of absorption lines of the same shape. The computation time is almost independent of the number of absorption lines. In many cases, this method allows increased speed and accuracy compared with conventional line-by-line methods.
A general computer program was developed to calculate the reflectivity, transmissivity, and absorptivity of nonideal multilayer structure devices. The program allows for error-based variation in layer thicknesses and ...
详细信息
A general computer program was developed to calculate the reflectivity, transmissivity, and absorptivity of nonideal multilayer structure devices. The program allows for error-based variation in layer thicknesses and also for the formation of interfacial layers between the primary layers. The main text of the program consists of the calculation of the matrix elements of the characteristic matrix T for any given two-component layer structure. The treatment is not restricted to any particular range of wavelength, type of material forming the layer structure, or number of layers in the chosen system. The pertinent parameters entering the calculations are the thicknesses of the individual layers (which are permitted to vary randomly within limit of error); the thicknesses of the interfacial layers; the complex indices of refraction of the sub-some strate, the pertinent layers, and the surrounding ambience; and the structural makeup of the layer stacking.
An algorithm for the accelerated convolution of the Lorentz function with spectral line data has been developed. The method involves the decomposition of the Lorentz function into subfunctions spanning finite domains....
详细信息
An algorithm for the accelerated convolution of the Lorentz function with spectral line data has been developed. The method involves the decomposition of the Lorentz function into subfunctions spanning finite domains. The subfunctions are convolved independently with line data at appropriate sampling intervals. The spectral absorption is obtained by superposition of the independent convolutions. A criterion for the specification of the sampling interval is described.
The impulse response and bandwidth of GeO(2)-doped and B(2)O(3)-doped multimode optical fibers are calculated from their measured refractive index profiles. The computational method is based on the WKB solution of the...
详细信息
The impulse response and bandwidth of GeO(2)-doped and B(2)O(3)-doped multimode optical fibers are calculated from their measured refractive index profiles. The computational method is based on the WKB solution of the guided mode problem in which the pulse delay time of each mode is determined with profile dispersion being taken into account. Accurate profiles are obtained by a newly developed focusing technique, which allows measurements to be made on whole-fiber samples. The predicted bandwidths of the GeO(2)-doped fibers range from approximately 200 to 1200 MHz-km and are in good agreement with the bandwidths and impulse responses previously measured by frequency-domain and time-domain optical shuttle pulse techniques on kilometer lengths of the fibers.
An analytical procedure for the calculation of the derivatives of the reflectance R of a dielectric multilayer stack is presented. Considered are the derivatives (?R/?nk)d, (?R/?nk)D, (?R/?dk)n, and (?R/?Dk)n, nk, dk,...
详细信息
An analytical procedure for the calculation of the derivatives of the reflectance R of a dielectric multilayer stack is presented. Considered are the derivatives (?R/?nk)d, (?R/?nk)D, (?R/?dk)n, and (?R/?Dk)n, nk, dk, and Dk being the refractive index, the thickness, and the effective optical thickness of the kth layer, respectively. These calculations lead to a computational algorithm which, as compared with the method using finite difference approximation, reduces the computer time by a factor of f (the total number of layers).
A new computational method for calculating and correcting the errors of the optical path difference in Fourier spectrometers is presented. This method only requires an one-sided interferogram and a single well-separat...
详细信息
A new computational method for calculating and correcting the errors of the optical path difference in Fourier spectrometers is presented. This method only requires an one-sided interferogram and a single well-separated line in the spectrum. The method also cancels out the linear phase error. The practical theory of the method is included, and an example of the progress of the method is illustrated by simulations. The method is also verified by several simulations in order to estimate its usefulness and accuracy. An example of the use of this method in practice is also given.
暂无评论