Search

Laser & photonics reviews 16, 2100268 (2022). doi:10.1002/lpor.202100268, The Free-Electron Laser (FEL) FLASH offers the world-wide still unique capability to study ultrafast processes with high-flux, high-rate XUV and soft X-ray pulses. The vast majority of experiments at FLASH are of pump-probe type and thus rely as well on optical ultrafast lasers. Here, a novel FEL facility laser is reported which combines the high average power output of Yb:YAG amplifiers with spectral broadening in a Herriott-type multi-pass cell and subsequent pulse compression to sub-100 fs durations. Compared to the previously employed laser utilizing optical parametric amplification, the new system comes with significantly improved noise figures, compactness, simplicity and power efficiency. It provides FLASH users 10 Hz repetition rate laser bursts with 800 𝜇s long trains of up to 800 pulses being optically synchronized to the FEL bursts with femtosecond precision. In the experimental chamber, pulses with up to 50 𝜇J energy, 60 fs FWHM duration and 1 MHz rate at 1.03 𝜇m wavelength are available and can be adjusted by computer-control. First cross-correlation measurements with the FEL pulses at the plane-grating monochromator photon beamline are demonstrated, proofing the suitability of the new laser for user experiments at FLASH., Published by Wiley VCH, Weinheim

10th EPS-QEOD Europhoton Conference on Solid-State, Fibre, and Waveguide Coherent Light Sources, (EUROPHOTON 2022) , Hannover, Germany, 28 Aug 2022 - 2 Sep 2022; The European physical journal / Web of Conferences 267, 01057 (2022). doi:10.1051/epjconf/202226701057, Optical frequency comb lasers are used in many applications in science and technology. For most applications output power levels around a few watts are sufficient. However, some applications require significant higher power ranges, for example to drive extreme nonlinear processes in gases for extreme ultraviolet (XUV) frequency comb generation. Although, efficient power scaling of fiber-frequency combs to the 100 W level was demonstrated more than 10 years ago [1] and recently kW average power levels on CEP (carrier-envelope phase) stabilized fiber laser systems were achieved [2], there are still only a few high-power frequency comb systems reported to date [3], typically requiring a team of experienced laser scientists for operation. Here we demonstrate the first steps towards closing the gap in versatility and user-friendliness of high-power optical frequency comb systems by introducing digital controls for pulse shaping, dispersion management and comb-stabilization on a 65 MHz Yb-fiber frequency comb system delivering more than 88 W output power., Published by EDP Sciences, Les Ulis

In dual-comb spectroscopy, the maximal spectral coverage and the minimal measurement time depend quadratically on the lasers’ pulse repetition rate. Here, we demonstrate a high-repetition rate 1 GHz dual-comb spectrometer based on low-noise Erbium-doped mode-locked lasers.

The popularity of renewable energy has increased dramatically in the last decade as it\ud becomes increasingly apparent that an alternative to fossil fuel is required. In order for this\ud market to continue to grow, there are a number of technical issues which must be overcome.\ud One such issue is the instability of power supplies which rely on unpredictable natural\ud resources. A popular solution to this problem is the use of a number of complementary\ud renewable power sources to create a stable power network serving a small geographical\ud area. In this project, a novel control solution for such a system is proposed and modelled\ud using a new approach.\ud A comprehensive review of the existing research literature was used to place in context the\ud hybrid renewable energy concept. This included identification of a system topology as well\ud as the novel control solution. A model of the system has been developed using a\ud combination of PSim and MATLAB. This model allowed for the operation of the system to be\ud simulated and subsequently verified. Upon completion of successful system level simulation\ud testing, VHDL implementations of the control solution were created and incorporated into the\ud model. Further simulations were then carried out based on a specific hardware target, an All\ud Programmable System-on-Chip (APSOC) device featuring a dual-core CPU and an FPGA\ud fabric.\ud The novel control solution is primarily aimed at the optimal control of the system’s power\ud converters. This controller employs a Neuro-Fuzzy algorithm to provide gain scheduling for a\ud PI type controller. The test results indicate that improvements were achieved in the stability\ud of the power converters in comparison to more traditional approaches, offering improved\ud response times and a reduction of the output voltage error. Moreover, a state-based\ud algorithm is utilised, which was demonstrated to ensure that the renewable energy sources\ud are optimally complementary.