High-capacity and multi-dimensional orbital angular momentum multiplexing holography.

Optical holography has been investigated for enhancing information capacity and encryption. Here, the multi-vortex geometric orbital angular momentum (MVG-OAM) multiplexing holography is proposed and experimentally implemented, which encodes information into MVG beams with different central OAM, sub-beam OAM, and coherent-state phase. The orthogonality of the above three parameters are analyzed, respectively, which point out the feasibility of using them for holographic multiplexing. A three-dimensional multiplexing holography is realized by combining these three parameters, which offers potential applications for information storage, optical encryption, and display.

Bidirectional ring amplifier with twin pulses for high-power lasers.

A novel bidirectional ring amplifier with twin pulses for high-power lasers is proposed, and the performances on output energy capability and extraction efficiency are comprehended with detailed simulation. The results show that an extraction efficiency of 62.3% and the output energy of 13.4 kJ per pulse at the B integral limit can be obtained at low average fluence of 10.3 J/cm2 and the low injection energy of 3.9 mJ in the bidirectional ring amplifier. Compared with the multi-pass amplifier, the bidirectional ring amplifier is more compact and the extraction efficiency is much higher at low injection energy and low laser fluence operation, which is beneficial to simplify the preamplifier system and reduce the effects of nonlinear phase shift.

Diffraction of volume Bragg gratings under high flux laser irradiation.

Diffraction property of transmitting volume Bragg gratings (VBGs) recorded in photo-thermo-refractive glass (PTR) is studied under the irradiation of a continuous-wave fiber laser with flux of 1274 W/cm2. Dependence of temperature characteristics of VBGs prepared by different crystallization temperatures is presented. When temperature of VBGs rises up to 33°C, there are a 2.7% reduction and 1.59% ripple of diffraction efficiency for VBGs. The period variation caused by the thermal expansion of VBGs is used to explain the reduction of diffraction efficiency, and experimental results are in agreement with theoretical analysis.

Optimization of spatial filter with volume Bragg gratings in photo-thermo-refractive glass.

We present a method for optimizing spatial filter performance by inserting volume Bragg gratings (VBGs) in front of the traditional spatial filters. The experimental results show that the cutoff frequency is modified with the insertion of VBGs. We also demonstrate the optimization of filtering performance in both the spatial and frequency domains, with detailed comparison of near-field modulation, contrast ratio, and power spectral density of output laser beams.