An economical way to extract semiconducting single-walled carbon nanotubes from common single-walled carbon nanotubes by the liquid-phase exfoliation method was demonstrated. Using the extracted samples as a saturable absorber, a passively Q-switched Nd : YVO4 laser was realized, delivering a pulse duration of 83 ns at a repetition rate of 290 kHz, resulting in a maximum peak power of 1.3 W. Such an outstanding saturable absorption might be caused by high diameter concordance and semi-conducting property.
A technique which takes advantage of distributed feedback laser diode (DFB-LD) wavelength scanning to measure water
vapor concentration is presented. Concentration is gotten by peak absorption rate according to Beer-Lambert law and
absorption coefficient of water vapor in HITRAN database. Theoretical work on the pressure affection to light intensity
absorption rate has been done, a scheme is presented to cope with the affection of overlap of two adjacent lines, it takes
advantage of the peak absorption difference between 1368.597nm and 1367.862 nm, and the difference value is used to
calculate the water-vapor concentration.
The Tuneable Transmitter Assembly is a high performance tuneable transmitter for use in the C or L wavelength bands of and suited to regional metro and long-haul applications. The key performance attributes of the TTA module is successfully demonstrated in this paper.
Under the influence of self-frequency shift, the interactions between in-phase and out-phase neighboring fundamental and second-order optical solitons are investigated numerically, and the impacts of soliton interactions to timing jitter are analyzed. It is found that under the influence of self-frequency shift, the periodic collision of neighboring fundamental in-phase soliton pair is broken. They are apart from each other rapidly after one collision and the self-frequency shift phenomenon is much more obvious after the collision. While for neighboring out-phase fundamental soliton pair, two solitons both shift to the dropping edge and the impacts of self-frequency shift are weaker than that of in-phase soliton pair. For second-order solitons, either in-phase or out-phase soliton pair will be split. Two split stronger solitons will collide with each other during the propagation in the optical fiber and the difference between in-phase soliton pair and out-phase soliton pair exists that the interactions of out-phase pair is weaker than that of in-phase soliton pair and the collision distance of out-phase pair is much longer than that of in-phase soliton pair. A nonlinear gain can be used to effectively suppress soliton interactions as well as effects of soliton self-frequency shift, and stabilize the soliton propagation.
In this paper, a wavelet-based fractal image coding algorithm is proposed. The conventional fractal image coding in spatial domain is extended to wavelet domain by taking advantage of the self-similarities among different wavelet subtrees through proper affine transformation. This method is based on the combination of the theory of multi-resolution analysis with iterated function systems by introducing some effective block-classification schemes. The original image is first transformed into wavelet domain in which fractal compression and arithmetic coding are performed. By classifying D blocks and R blocks set in this domain, the approach can significantly reduce the computation complexity and encoding time. Meanwhile, the hybrid image compression algorithm obtains much better coding performance in terms of PSNR with error modification. This is the main advantage of this method. A set of experiments and simulations show the potentials of using these classification techniques in wavelet domain for futher improvements.
One common task of image interpolation is to enhance the resolution of the image, which means to magnify the image without loss in its clarity. Traditional methods often assume that the original images are smooth enough so as to possess continues derivatives, which tend to blur the edges of the interpolated image. A novel fast image interpolation algorithm based on wavelet transform and multi-resolution analysis is proposed in this paper. It uses interpolation and extrapolation polynomial to estimate the higher resolution informatoin of the image and generate a new sub-band of wavelet transform coefficients to get processed image with shaper edges and preserved singularities.