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Accelerating relativistic mirrors have long been recognized as viable settings where the physics mimic those of the black hole Hawking radiation. In 2017, Chen and Mourou proposed a novel method to realize such a system by traversing an ultra-intense laser through a plasma target with a decreasing density. An international AnaBHEL (Analog Black Hole Evaporation via Lasers) collaboration was formed with the objectives of observing the analog Hawking radiation, shedding light on the information loss paradox. To reach these goals, we plan to first verify the dynamics of the flying plasma mirror and characterize the correspondence between the plasma density gradient and the trajectory of the accelerating plasma mirror. We will then attempt to detect the analog Hawking radiation photons and measure the entanglement between the Hawking photons and their “partner particles”. In this paper, we describe our vision and strategy of AnaBHEL using the Apollon laser as a reference, and we report on the progress of our R&D concerning the key components in this experiment, including the supersonic gas jet with a graded density profile, and the superconducting nanowire single-photon Hawking detector. In parallel to these hardware efforts, we performed computer simulations to estimate the potential backgrounds, and derived analytic expressions for modifications to the blackbody spectrum of the Hawking radiation for a perfectly reflecting point mirror, due to the semi-transparency and finite-size effects specific to flying plasma mirrors. Based on this more realistic radiation spectrum, we estimate the Hawking photon yield to guide the design of the AnaBHEL experiment, which appears to be achievable.

Simulations of photoneutron generation are presented for the anticipated experimental campaign at ELI-ALPS using the under-commissioning e-SYLOS beamline. Photoneutron generation is a three-step process starting with the creation of a relativistic electron beam which is converted to gamma radiation, which in turn generates neutrons via the γ,n interaction in high-Z material. Electrons are accelerated to relativistic energies using the laser wakefield acceleration (LWFA) mechanism. The LWFA process is simulated with a three-dimensional particle in cell code to generate an electron bunch of 100s pC charge from a 100 mJ, 9 fs laser interaction with a helium gas jet target. The resultant electron spectrum is transported through a lead sphere with the Monte Carlo N-Particle (MCNP) code to convert electrons to gammas and gammas to neutrons in a single simulation. A neutron yield of 3×107 per shot over 4π is achieved, with a corresponding neutron yield per kW of 6×1011 n/s/kW. The paper concludes with a discussion on the attractiveness of LWFA-driven photoneutron generation on high impact, and societal applications.

The thin-film post-compression technique has the ability to reduce the pulse duration in PW-class lasers, increasing the peak power. Here, the nonlinear response of an increasingly available optical thermoplastic demonstrates enhanced spectral broadening, with corresponding shorter pulse duration compared to fused silica glass. The thermoplastic can be used close to its damage threshold when refreshed using a roller mechanism, and the total amount of material can be varied by folding the film. As a proof-of-principle demonstration scalable to 10-PW, a roller mechanism capable of up to 6 passes through a sub-millimeter thermoplastic film is used in vacuum to produce two-fold post-compression of the pulse. The compact design makes it an ideal method to further boost ultrahigh laser pulse intensities with benefits to many areas, including driving high energy acceleration.

In order to accelerate ions by a laser, we go back to the original and the fundamental idea of how longitudinal field structure generation can be carried out in an ionized media and how particles may be trapped by the created wakefield. The latter condition is characterized by the phase velocity of the longitudinal structure vph be equal to the particle trapping width vtr. Since the trapping width is inversely proportional to the square-root of the mass of the accelerated particles, this width is much shorter for ions than for electrons. Thus, our dictum for laser ion acceleration is to impose a near critical density trap to decelerate laser group velocity, vg and subsequently to generate longitudinal wakefield to be able to trap ions under the condition of vtr = vph. We demonstrate this concept by PIC simulation and find that this method is effective, and the efficiency of laser ion acceleration is enhanced by a couple of orders of magnitude toward unity.

Ultra-compact electron beam technology based on laser wakefield acceleration (LWFA) could have a significant impact on radiotherapy treatments. Recent developments in LWFA high-density regime (HD-LWFA) and low-intensity fiber optically transmitted laser beams could allow for cancer treatments with electron beams from a miniature electronic source. Moreover, an electron beam emitted from a tip of a fiber optic channel could lead to new endoscopy-based radiotherapy, which is not currently available. Low-energy (10 keV–1 MeV) LWFA electron beams can be produced by irradiating high-density nano-materials with a low-intensity laser in the range of ~1014 W/cm2. This energy range could be useful in radiotherapy and, specifically, brachytherapy for treating superficial, interstitial, intravascular, and intracavitary tumors. Furthermore, it could unveil the next generation of high-dose-rate brachytherapy systems that are not dependent on radioactive sources, do not require specially designed radiation-shielded rooms for treatment, could be portable, could provide a selection of treatment energies, and would significantly reduce operating costs to a radiation oncology clinic.

Sub-10 attosecond pulses (APs) with half-cycle electric fields provide exceptional options to detect and manipulate electrons in the atomic timescale. However, the availability of such pulses is still challenging. Here, we propose a method to generate isolated sub-10 attosecond half-cycle pulses based on a cascade process naturally happening in plasma. A backward AP is first generated by shooting a moderate overdense plasma with a one-cycle femtosecond pulse. After that, an electron sheet with the thickness of several nanometers is formed and accelerated forward by the electrostatic field. Then this electron sheet goes through unipolar perturbations driven by the tail of the first-stage AP instead of the initial laser pulse. As a result, a half-cycle sub-10 AP is cascadedly produced in the transmission direction. Two-dimensional particle-in-cell simulations indicate that an isolated half-cycle pulse with the duration of 7.3 attoseconds can be generated from the cascaded scheme. Apart from a one-cycle driving pulse, such a scheme also can be realized with a commercial 100 TW 25 fs driving laser by shaping the pulse with a relativistic plasma lens in advance.

Though wakefield acceleration in crystal channels has been previously proposed, x-ray wakefield acceleration has only recently become a realistic possibility since the invention of the single-cycled optical laser compression technique. We investigate the acceleration due to a wakefield induced by a coherent, ultrashort x-ray pulse guided by a nanoscale channel inside a solid material. By two-dimensional particle-in-cell computer simulations, we show that an acceleration gradient of TeV/cm is attainable. This is about 3 orders of magnitude stronger than that of the conventional plasma-based wakefield accelerations, which implies the possibility of an extremely compact scheme to attain ultrahigh energies. In addition to particle acceleration, this scheme can also induce the emission of high energy photons at ∼O(10–100) MeV. Our simulations confirm such high energy photon emissions, which is in contrast with that induced by the optical laser driven wakefield scheme. In addition to this, the significantly improved emittance of the energetic electrons has been discussed.

Technologies, performances and maturity of ultrafast fiber lasers and fiber delivery of ultrafast pulses are discussed for the medical deployment of laser-wake-field acceleration (LWFA). The compact ultrafast fiber lasers produce intense laser pulses with flexible hollow-core fiber delivery to facilitate electron acceleration in the laser-stimulated wake field near treatment site, empowering endoscopic LWFA brachytherapy. With coherent beam combination of multiple fiber amplifiers, the advantages of ultrafast fiber lasers are further extended to bring in more capabilities in compact LWFA applications.

The application of femtosecond lasers in corneal transplant surgery requires high pulse energies to compensate for the strong optical scattering in pathological corneas. However, excessive energies deteriorate the quality of the incisions. The aim of this study is to demonstrate the dependence of side effects on local radiant exposure, numerical aperture, and tissue properties, to quantify the penetration depth of the laser for individual corneas, and to provide a method for optimizing the energy in the volume of the cornea. We examine histological and ultrastructural sections of clear and edematous corneas with perforating and lamellar incisions performed at different pulse energies. We demonstrate that the augmented energies in edematous corneas may result in unwanted side effects even when using high numerical apertures. The dependence of the laser beam penetration depth on pulse energy is evaluated by histology and an exponential decrease is observed. We show that the penetration length can be determined by evaluating the backscattered second-harmonic emission associated with the nonlinear optical properties of the tissue. This approach represents a noninvasive method for the in situ quantification of the laser beam attenuation, enabling us to adapt the pulse energy accordingly. Experiments using adapted energies show that the side effects are minimized. [ABSTRACT FROM AUTHOR]