Ultrafast 550-W average-power thin-disk laser oscillator

We present a SESAM modelocked ultrafast thin-disk laser oscillator providing 550 W of average output power with 852 fs pulses at 5.5 MHz repetition rate. To the best of our knowledge, this represents the highest average output power ever achieved from a modelocked oscillator. To reach this significant power scaling, a new replicating cavity design for modelocked oscillators is utilized. The oscillator delivers 103 MW of peak power with a pulse energy of 100 µJ at a beam quality of M²< 1.2, with a high optical-to-optical efficiency of 35%. As well as providing record average output power, this oscillator thus also provides, to the best of our knowledge, the highest pulse energy from any modelocked oscillator and the highest peak power from any SESAM modelocked oscillator. Advances in SESAM design and manufacturing that enabled this result are discussed, as well as practical challenges when scaling oscillators to the kW-class

Supplementary document for Ultrafast Yb:YAG laser oscillator with gigahertz repetition rate - 6577590.pdf

Overview of gigahertz solid-state laser

Anapoles in Free-Standing III–V Nanodisks Enhancing Second-Harmonic Generation

Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: a lack of energy losses and invisibility to the propagating electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, in which a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range. We show a novel approach to creating nanoantennas by slicing III–V nanowires into standing disks using focused ion-beam milling. We experimentally demonstrate the suppression of the far-field radiation and the associated strong enhancement of the second-harmonic generation from the disk nanoantennas. With a theoretical analysis of the electromagnetic field distribution using multipole expansions in both spherical and Cartesian coordinates, we confirm that the demonstrated nonradiating configurations are anapoles. We expect that the presented procedure of designing and producing disk nanoantennas from nanowires becomes one of the standard approaches to fabricating controlled chains of standing nanodisks with different designs and configurations. These chains can be essential building blocks for new types of lasers and sensors with low power consumption