Atomic, Molecular, Optical Science

High speed spatial light modulators for quantum control

The ability to control and program light is fundamental to science and technology, shaping a vast array of
fields from optical communications and microscopy, sensing, and astronomy. For some fields, the slow
devices commercially available today, known as spatial light modulators, are a core bottleneck for mature
systems – such as 3D holography, imaging through scattering media, and quantum computing.
Motivated by quantum control applications, where atomic or solid state atom-like qubits require high
speed addressing in hundreds of sites, and where photonic quantum computing has been explored using
spatial modes that require millions of degrees of freedom, I explore the development of high speed spatial
light modulators: devices that can control many spatial degrees of freedom of light at high speeds. In this
talk I discuss three different platforms that achieve this, each of which offers new advancements and
insights: First, a nanophotonic plasmonic modulator with liquid crystals fabricated in a “fabless” bulk
CMOS process[1] which can potentially democratize nanophotonics research, as well as allow for
multi-layer structures, scalability and electronic integration. Second, a Lithium Niobite on Silicon
device[2], where thin film LN with a guided mode resonance is bonded to a commercial CMOS
backplane, allowing for GHz speed modulation arising from the Pockels effect. Finally, a photonic crystal
array using specially designed photonic crystal cavities[3], working at ~0.2 GHz. With 64-100 pixels, this
demonstration is one of the largest scale foundry made devices ever made. The automated ‘holographic
trimming’ achieved a record picometre precision alignment of the cavity resonance for 81 devices.
These works pave the way for programmable control of millions of degrees of freedom of light at high
rates.
 

PhD Defense

Asymmetric Effects in Shock Injection for Laser-Plasma Electron Acceleration

Abstract: Laser-plasma acceleration (LPA), using plasma waves as a medium for transferring energy from an ultra-intense laser pulse to directional kinetic energy of electrons, is a promising candidate for the next generation of particle accelerators, capable of reaching the same energies at less than 0.1% acceleration length compared to classical RF-cavity based accelerators, thanks to the plasma medium's support of extremely large fields. LPA-based multi-GeV electrons [1] and LPA-based free electron lasers [2] have already been demonstrated, and LPA-based medical accelerators for oncological particle therapy are at the focus of interest of many research groups and commercial companies in academia and industry. However, one drawback of current laser-plasma accelerators is their beam quality, notably affected by the process of trapping and injection of ambient electrons into the in-plasma accelerating structure – a process whose improved understanding and development will unlock many other potential uses for these compact accelerators. In my research, the femtosecond relativistic electron microscopy (FREM) method [3], a technique significantly developed in our lab, has been used to probe the highly nonlinear dynamics of one of the most common injection implementations, razor-blade shock injection [4]. We have discovered that the tilt of the generated shock can induce transverse oscillations in the injected electrons until a part of the accelerated bunch splits out of the accelerating structure and drives its own plasma wave. This phenomenon, never reported before, was investigated and characterized, and our hope is that the insights gained by this research will contribute to the improvement of the injection process, and consequently to the overall quality of LPA-based electron beams, enabling this technology to fulfill the promise it holds for so many fields in our lives.

[1] A. J. Gonsalves et al. Petawatt Laser Guiding and Electron Beam Acceleration to 8 GeV in a Laser-Heated Capillary Discharge Waveguide. Phys. Rev. Lett. 122 084801 (2019).

[2] Marie Labat et al. Seeded free-electron laser driven by a compact laser plasma accelerator. Nature Photonics 17 150-156 (2023).

[3] Yang Wan, Sheroy Tata, Omri Seemann, Eitan Y. Levine, Slava Smartsev, Eyal Kroupp, and Victor Malka. Femtosecond electron microscopy of relativistic electron bunches. Light: Science & Applications 12 116 (2023).

[4] K. Schmid et al. Density-transition based electron injector for laser driven wakefield accelerators. Phys. Rev. ST Accel. Beams 13 091301 (2010).