Showing 3 results for Polymer.
A. Gharavi, H. Karimi-Alavijeh, E. Sarailou, M.–a. Baghban, G.–m. Parsanasab,
Volume 2, Issue 1 (2-2008)
Abstract
In this paper, we have reported the fabrication of two-dimensional photonic crystals, using a direct writing method in azo polymers. Periodic structures have been fabricated using the interference patterns of two coherent laser beams. The frequency response of the initial one-dimensional structure shows an attenuation of 19.3dB at 1554nm. The twodimensional structure shows 8.3dB and 11.3dB of attenuation at 1554nm in two perpendicular main axes of the structure. The diffraction pattern shows the characteristic rectangular pattern.
M. Dezhkam, M. Soltanolkotabi,
Volume 3, Issue 1 (3-2009)
Abstract
This paper describes the passive Qswitch, based on polymer and organic dye BDN, of a pulsed Nd:YAG laser. Pulses of 27ns duration and peak power of 1.7MW for initial transmission of Q-switch 18.4% 0 T = have been obtained. We have obtained Q-switching efficiency of 77% for train of pulses of 31 and 76.2% 0 T = at the pump energy of 98J. We have also obtained the dependency of laser pulse characteristics on pump energy and initial transmission of Q-switch. We have obtained the damage threshold of this Q-switch at the pulse duration of 27ns to be13J cm2 .
Morteza Janfaza, Hamed Moradi, Arsalan Jalil,
Volume 17, Issue 2 (6-2023)
Abstract
In this study, we present the findings derived from our simulation and experimental investigation of a distributed optical fiber acoustic sensor. The proposed sensor operates by utilizing the self-interference of Rayleigh backscattering. When the optical pulse propagates through the optical fiber, the phase of the Rayleigh backscattered light changes at the location where the acoustic signal is present. This phase change is then amplified through the self-interference of two Rayleigh backscattered beams in the Michelson interferometer scheme. This study aims to present the Phase Generated Carrier (PGC) demodulation method along with the arctangent function (ATAN) and the Coordinate Rotation Digital Computer (CORDIC) algorithm. This method offers a simple and efficient algorithm for computing hyperbolic and trigonometric functions. The system allows for the detection of acoustic waves caused by sinusoidal disturbances with a spatial resolution of approximately 20 m.
