Xiumin Gao

Tunable three-dimensional intensity distribution by a pure phase-shifting apodizer

The three-dimensional distribution of light intensity that is modulated by a pure phase-shifting apodizer is studied. Results show that the Strehl ratio can be altered by the proposed apodizer and by the waist width of incident Gaussian beams. By changing geometrical parameters of the proposed apodizer, we can increase the focal depth to several times that of the original system. The proposed apodizer can also be used to realize focal splitting and local minimum of intensity, which may be advantageous for constructing an optical trap. Furthermore, the local minimum of intensity number is tunable by changing the parameters of the apodizer.

Tunable focal depth of an apodized focusing optical system

The axial intensity distribution and focal depth of an apoclized focusing optical system are theoretically investigated with two kinds of incident light fields: a uniform-intensity-distribution beam and a Gaussian beam. Both a low-numerical-aperture and a high-numerical-aperture optical system are considered. Numerical results show that the depth of focus can be adjusted by changing the geometrical parameters and transmissivity of the apodizer in the focusing optical system. When a Gaussian beam is employed as the incident beam, the waist width also affects the depth of focus. The tunable range of the focal depth is very considerable. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Static recording characteristics of super-resolution near-field structure with bismuth mask layer

Static recording characteristics of super-resolution near-field structure with bismuth (Bi) mask layer and antimony (Sb) mask layer were investigated and compared. The experimental results show that Bi mask layer can also concentrate energy into the center of a laser beam at a low laser energy input similar to Sb, which may be because that Bi film exhibits giant nonlinearity at low laser intensity. The direct observation of laser-recording marks may help better understand the working mechanism of the super-RENS, super-resolution ablation, and other nonlinear switching phenomena.

Static testing system for blue-ray optical data storage

Measurement technology plays an important role in the research of optical storage. Aiming at constructing research platform for blue-ray optical data storage, we designed and built a modularized static testing system, in which laser wavelength is 406.7nm. Modulation/demodulation technique is employed to weaken the test noise. The focus move mode decreases the requirement in size of samples. And Piezoeletronic nano-positioner is used to facilitate the relocation of recording marks and improve test repeatability. Experimental results are also given to verify the performance of the static testing system.