We report on the investigation of intermode beating mode-locked (IBML) pulse generation in a simple all-fiber Tm$^{3+}$-doped double clad fiber laser (TDFL). This IBML TDFL is implemented by matching longitudinal-mode frequency between 793 nm laser and TDFL without extra mode locker. The central wavelength of ${\sim}1983~\text{nm}$, the fundamental pulse frequency of ${\sim}9.6~\text{MHz}$ and the signal-to-noise ratio (SNR) of ${>}50~\text{dB}$ are achieved in this IBML TDFL. With laser cavity optimization, the IBML TDFL can finally generate an average output power of 1.03 W with corresponding pulse energy of ${\sim}107~\text{nJ}$. These results can provide an easily accessible way to develop compact large-energy, high-power TDFLs.

We report on the energetic and beam quality performance of the second to the last main amplifier section HEPA I of the PEnELOPE laser project. A polarization coupled double-12-pass scheme to verify the full amplification capacity of the last two amplifiers HEPA I and II was used. The small signal gain for a narrow-band continuous wave laser was 900 and 527 for a broadband nanosecond pulse, demonstrating 12.6 J of output pulse energy. Those pulses, being spectrally wide enough to support equivalent 150 fs long ultrashort pulses, are shown with an excellent spatial beam quality. A first active correction of the wavefront using a deformable mirror resulted in a Strehl ratio of 76% in the single-12-pass configuration for HEPA I.

In this paper we review the provision of the laser diagnostics that are installed on the Vulcan laser facility. We will present strategies for dealing with the energy of high energy systems and with ways of handling the beam sizes of the lasers. We present data captured during typical experimental campaigns to demonstrate their reliability and variation in shot to shot values.

An energy measurement system in a Large-aperture high power laser experiment platform is introduced. The entire measurement system includes five calorimeters, which carry out the energy measurement of the fundamental frequency before the frequency conversion unit, remaining fundamental frequency, remain second-harmonics, third harmonics, as well as the energy balance measurement after the frequency conversion unit. Combinational indirect calibration and direct calibration are employed to calibrate the sampling coefficients of the calorimeters. The analysis of the data showed that, regarding the energy balance coefficients, combinational calibration approach gives a higher precision, and leads to an energy balance with 1%; and regarding the energy sampling coefficients for the various wavelengths after the frequency conversion, the results from direct and combinational calibration are consistent. The uncertainties for all energy sampling coefficients are within 3%, which guarantees the reliability of the energy measurement for the laser facility.