Transverse superresolution with the radial continuous transmittance filter

The radial continuous transmittance filter is presented to realize transverse superresolution. It consists of two parallel polarizers and a radial birefringent element sandwiched between of them. By adjusting the angle between optical axis of the radial birefringent element and the polarization direction of the polarizers, transverse superresolution can be realized. But transverse superresolution is obtained at the cost of the axial resolution and the increase of the side-lobes in strength. So we then mend such filter, with it not only enhance the transverse resolution but also suppress the influence of the side-lobes and the reduction of the axial resolution. At the same time, the Strehl ratio increases. The advantage of such a filter used in superresolution technique is that it is easy to fabricate because its fabrication does not deal with the variation of the phase. (c) 2005 Elsevier GmbH. All rights reserved.

Transverse intensity distributions of a broadband laser modulated by a hard-edged aperture

By means of the Huygens-Fresnel diffraction integral, the field representation of a laser beam modulated by a hard-edged aperture is derived. The near-field and far-field transverse intensity distributions of the beams with different bandwidths are analyzed by using the representation. The numerical calculation results indicate that the amplitudes and numbers of the intensity spikes decrease with increasing bandwidth, and beam smoothing is achieved when the bandwidth takes a certain value in the near field. In the far field, the radius of the transverse intensity distribution decreases as the bandwidth increases, and the physical explanation of this fact is also given. (c) 2005 Optical Society of America.

Fields of apertured polychromatic laser beams with Gaussian and Hermite-Gaussian transverse modes

Starting from the Huygens-Fresnel diffraction integral, the field expressions of apertured polychromatic laser beams with Gaussian and Hermite-Gaussian transverse modes are derived. Influence of the bandwidth on the intensity distributions of the laser beams is analyzed. It is found that when the bandwidth increases, the amplitudes and numbers of the intensity spikes decrease and beam uniformity is improved in the near field and the width of transverse intensity distribution of the apertured beams decreases in the far field. Thus, the smoothing and narrowing effects can be achieved by increasing the bandwidth. Also, these effects are found in the laser beams with Hermite-Gaussian transverse modes as the bandwidth increases.(c) 2006 Elsevier Ltd. All rights reserved.

New approach for improving transverse superresolution in optical data storage

We have proposed a new confocal readout system which is based on the combination of two N-zone circular phase-only transverse superresolving pupils to improve transverse superresolution. The procedure for designing such an improved system is presented. Results of comparisons between the performance of the proposed system and the transverse superresolving pupils indicate that with the same Strehl ratio the former has much higher transverse superresolution capacity and significantly lower sidelobe intensity. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

New approach for improving transverse superresolution in optical data storage

We have proposed a new confocal readout system which is based on the combination of two N-zone circular phase-only transverse superresolving pupils to improve transverse superresolution. The procedure for designing such an improved system is presented. Results of comparisons between the performance of the proposed system and the transverse superresolving pupils indicate that with the same Strehl ratio the former has much higher transverse superresolution capacity and significantly lower sidelobe intensity. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Transverse mode formation in longitudinally pumped miniature slab lasers

The formation of transverse modes in longitudinally pumped miniature slab lasers is investigated theoretically and experimentally. The longitudinally non-uniform gain-guiding is studied by expanding the electric field into the Hermite-Gaussian functions that satisfy boundary conditions of the resonator. Non-Gaussian transversal beam profiles in the near field are found and the beam diameter is reduced when the pump spot becomes smaller. The experimental observation agrees with the theoretical calculation.

High power single transverse mode operation of a tapered large-mode-area fiber laser

To get high output power with good beam quality, a tapered section is introduced to large-mode-area (LMA) Yb-doped fiber laser. Output characteristics of the fiber laser without tapered section and with tapered section are compared experimentally. When the launched pump power is 119.1 W, 77.9 W with M-2 3.08 and 56.4 W with M-2 1.14 can be obtained, respectively. The corresponding slope efficiencies are 71.8% and 54.1%, respectively. Although output power of the tapered fiber laser has 30.6% penalty, brightness of it is as much as 5.28 times of the fiber laser without tapered section. Moreover, spectra of them are measured. It is found that tapered section makes lasing wavelength of the fiber laser shorter. (c) 2007 Elsevier B.V. All rights reserved.

Transverse target single-spin asymmetry in inclusive electroproduction of charged pions and kaons

Single-spin asymmetries were investigated in inclusive electroproduction of charged pions and kaons from transversely polarized protons at the HERMES experiment. The asymmetries were studied as a function of the azimuthal angle psi about the beam direction between the target-spin direction and the hadron production plane, the transverse hadron momentum P-T relative to the direction of the incident beam, and the Feynman variable x(F). The sin psi* amplitudes are positive for pi(+) and K+ slightly negative for pi(-) and consistent with zero for K-, with particular P-T but weak x(F) dependences. Especially large asymmetries are observed for two small subsamples of events, where also the scattered electron was recorded by the spectrometer. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.