Yunxin Tang

Optical parametric chirped-pulse amplification source suitable for seeding high-energy systems.

A short-pulse source based on optical parametric chirped-pulse amplification (OPCPA) technology has been developed with properties that make it a suitable seed for a high-energy OPCPA system. This source generated a diffraction-limited pulse at 910 nm with a full bandwidth of > 165 nm and a spectrum having a transform-limited pulse duration of less than 15 fs. The technique has potential for generating bandwidths > 200 nm and pulse durations < 10 fs.

Development of a novel large bandwidth front-end system for high peak power OPCPA systems

In this paper we describe the development of a novel front-end capable of generating pulses with ≫100nm bandwidth at 910nm, a pulse duration ≪30fs and energies at the joule level. This system has been developed as a seed source for the development of a 10PW facility for the Vulcan laser. The development is based on large scale OPCPA with the goal of producing pulses with focused intensities ≫10²³ W/cm² and will be achieved by delivering pulses with ≫300J in ≪30fs onto target.

Transmission grating stretcher for contrast enhancement of high power lasers

We propose, for the first time, a transmission grating stretcher for high power lasers and demonstrate its superiority over conventional, reflective gold grating stretchers in terms of pulse temporal quality. We show that, compared to a conventional stretcher with the same stretching factor, the transmission-grating based stretcher yields more than an order of magnitude improvement in the contrast pedestal. We have also quantitatively characterized the roughness of the grating surfaces and estimated its impact on the contrast pedestal.

Novel ultra-fast broadband laser source at 910nm for Vulcan 10 PW OPCPA laser system

In this paper we have reported a jitter-free ultra-fast broadband OPA amplification in the sub-ps time domain at the repetition rate of 1 kHz. A novel broadband laser pulse source of ~180 nm (FWHM) at ~910 nm was demonstrated for Vulcan 10 PW OPCPA laser system development.

Experimental investigation of cross-polarized wave generated with focused spatially dispersed beam

The nonlinear process of cross polarized wave (XPW) generation, which has been broadly used for temporal contrast enhancement and spectral broadening [1, 2], continue to attract interest in different application schemes. A feature of space-time focusing (STF), which occurs at the focus of spatially dispersed beam, is to deliver highly localized intensity at the focus without incurring high non-linear losses during long distance propagation. A number of nonlinear optical processes have been used to study and to utilize STF: two-photon fluorescence [3], harmonic generation [4], plasma formation [5] and refractive index modification in solids [6]. In this paper XPW generation in BaFz has been studied at the SST conditions of a compressed femtosecond pulse.

Dual beam operation of the Astra-Gemini high power laser and upgrades to the Ti:Sapphire amplifiers

Special considerations of operating the dual beam facility Gemini are presented. Amplifiers in Astra have been upgraded to improve the contrast, stability and performance with wedged Ti:Sapphire crystals and spatial filtering.

Investigation of Contrast for Astra-Gemini laser

We report the recent progress in contrast compaign for Astra-Gemini, showing that the stretcher grating as the main source of the coherent contrast. Improvement was achieved by new gratings, and further enhanced by using double plasma mirrors.

Contrast Enhancement for Astra-Gemini Laser

We report on the contrast enhancement for Astra-Gemini laser following identifying the major source of coherent contrast, in conjunction with plasma mirrors. Replica prepulses were suppressed or eliminated by employing the wedged optics.

Investigation of Contrast of Astra-Gemini Laser

We report an investigation of the temporal contrast of the Astra-Gemini high power laser. Enhanced contrast by nearly an order of magnitude has been achieved by upgrading the commercial front-end to provide cleaner seed pulses.

Development of a Novel Large Bandwidth Front-End System for High Peak Power OPCPA Systems

We present the development of a novel large bandwidth front-end that is capable of supporting sub 30fs pulses, with 1J of energy at a 2Hz repetition rate that is centred at 910nm.