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Wang S.,University of Sichuan | Feng G.,University of Sichuan | Zhou S.,University of Sichuan | Zhou S.,North China Research Institute of Electro Optics
Applied Physics Letters | Year: 2014

Micro/nano patterning of ZnSe wafer is demonstrated by femtosecond laser irradiation through a diffracting pinhole. The irradiation results obtained at fluences above the ablation threshold are characterized by scanning electron microscopy. The microsized structure with low spatial frequency has a good agreement with Fresnel diffraction theory. Laser induced periodic surface structures and laser-induced periodic curvelet surface structures with high spatial frequency have been found on the surfaces of microsized structures, such as spikes and valleys. We interpret its formation in terms of the interference between the reflected laser field on the surface of the valley and the incident laser pulse. © 2014 AIP Publishing LLC. Source


Yang H.,University of Sichuan | Feng G.,University of Sichuan | Zhou S.,University of Sichuan | Zhou S.,North China Research Institute of Electro Optics
Optics and Laser Technology | Year: 2011

An investigation of thermal effects in a high-power Nd:YAG disk-type solid state laser pumped with different pump beam transverse profiles is carried out by numerical simulation based on the finite element method (FEM). Impact of the heat sink on the thermal effects is included in the simulation. The distribution of first principle stress, thermally induced birefringence, including the distribution and variation of the birefringence loss, are studied. The characteristics of the phase variation are analyzed with consideration of the temperature gradient, deformation, strain and thermal stress. Thermal lensing is explored as a function of pump power and of the radius pumped with different pump beam transverse profiles. The non-parabolic part of optical phase distortion is simulated. Furthermore, the characteristics of the bi-focus of the disk laser are also studied. Experiments on the maximum tensile stress distribution and depolarization loss are carried out. The presented calculations are in qualitative agreement with the experimental observations. © 2011 Elsevier Ltd. All rights reserved. Source


Du Y.,University of Sichuan | Feng G.,University of Sichuan | Li H.,University of Sichuan | Vargas J.,CSIC - National Center for Biotechnology | And 2 more authors.
Optics Letters | Year: 2012

A simple and compact point-diffraction interferometer with circular common-path geometry configuration is developed. The interferometer is constructed by a beam-splitter, two reflection mirrors, and a telescope system composed by two lenses. The signal and reference waves travel along the same path. Furthermore, an opaque mask containing a reference pinhole and a test object holder or test window is positioned in the common focal plane of the telescope system. The object wave is divided into two beams that take opposite paths along the interferometer. The reference wave is filtered by the reference pinhole, while the signal wave is transmitted through the object holder. The reference and signal waves are combined again in the beam-splitter and their interference is imaged in the CCD. The new design is compact, vibration insensitive, and suitable for the measurement of moving objects or dynamic processes. © 2012 Optical Society of America. Source


Zhou H.,University of Sichuan | Feng G.,University of Sichuan | Yao K.,University of Sichuan | Yang C.,University of Sichuan | And 3 more authors.
Optics Letters | Year: 2013

We investigate a tunable fluidic dye laser formed by a microcavity filled with a dye solution. We achieve a wide 18 nm tunability of the laser wavelength by controlling the cavity length for the first time. The microcavity is made of a silica capillary and two aligned fibers with end faces Au-coated. The Rhodamine 6G dye solution flowing through the microcavity is pumped by 532 nm wavelength laser pulses. Laser emission around 570 nm in the form of TE mode with a threshold of about 58 μJ/pulse is obtained. This work suggests a fiber-based convenient approach to achieve wavelength tunability and integration with lab-on-a-chip systems. © 2013 Optical Society of America. Source


Yang L.,University of Sichuan | Feng G.,University of Sichuan | Yi J.,University of Sichuan | Yao K.,University of Sichuan | And 2 more authors.
Applied Optics | Year: 2011

We have studied the random laser action in Rhodamine 6G (Rh6G) ethylene glycol solution with Al nanoparticles. The experiment results are obtained by pumping with a nanosecond (7 ns) laser pulse, which demonstrated the existence of effective random laser emission. It is found that the threshold of the random laser depends on the concentration of the Rh6G and the concentration of Al nanoparticles. The concentration and diameter of Al nanoparticles have effects on the optical path; a higher concentration or a larger diameter results in a shorter optical path length. Also multimode survival and mode competition have been observed at a relatively high concentration (0:08 M) of Rh6G, where the concentration of Al nanoparticles is 0:0015 M. © 2011 Optical Society of America. Source

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