Consistent characterization of semiconductor saturable absorber mirrors with singe-pulse and pump-probe spectroscopy

We study the comparability of the two most important measurement methods used for the characterization of semiconductor saturable absorber mirrors (SESAMs). For both methods, single-pulse spectroscopy (SPS) and pump-probe spectroscopy (PPS), we analyze in detail the time-dependent saturation dynamics inside a SESAM. Based on this analysis, we find that fluence-dependent PPS at complete spatial overlap and zero time delay is equivalent to SPS. We confirm our findings experimentally by comparing data from SPS and PPS of two samples. We show how to interpret this data consistently and we give explanations for possible deviations

Cutting-Edge High-Power Ultrafast Thin Disk Oscillators

A growing number of applications in science and industry are currently pushing the development of ultrafast laser technologies that enable high average powers. SESAM modelocked thin disk lasers (TDLs) currently achieve higher pulse energies and average powers than any other ultrafast oscillator technology, making them excellent candidates in this goal. Recently, 275 W of average power with a pulse duration of 583 fs were demonstrated, which represents the highest average power so far demonstrated from an ultrafast oscillator. In terms of pulse energy, TDLs reach more than 40 µJ pulses directly from the oscillator. In addition, another major milestone was recently achieved, with the demonstration of a TDL with nearly bandwidth-limited 96-fs long pulses. The progress achieved in terms of pulse duration of such sources enabled the first measurement of the carrier-envelope offset frequency of a modelocked TDL, which is the first key step towards full stabilization of such a source. We will present the key elements that enabled these latest results, as well as an outlook towards the next scaling steps in average power, pulse energy and pulse duration of such sources. These cutting-edge sources will enable exciting new applications, and open the door to further extending the current performance milestones

Characterization of InGaAs and InGaAsN semiconductor saturable absorber mirrors for high-power mode-locked thin-disk lasers

We report a comparative study of carrier dynamics in semiconductor saturable absorber mirrors (SESAMs) containing InGaAs quantum wells and InGaAsN quantum wells (QWs). The static and dynamic reflectivity spectra were measured with a Fourier-transform-infrared-spectrometer and a pump-probe setup, respectively. The influence of rapid thermal annealing (RTA) on carrier dynamics was studied. Due to the reduction of defect states by RTA we observed an increase of the static reflectivity and an increase of the electron–hole recombination time. We demonstrate that nitrogen incorporation causes a decrease of the static reflectivity of the SESAMs, an increase of the modulation depth, and a reduction of the carriers’ recombination time. We also investigated the mode-locking behavior of the SESAMs in an Yb:YAG thin-disk laser oscillator. The highest pulse energies directly obtained from a laser oscillator under stable operation conditions were achieved when using a SESAM with InGaAsN quantum wells

MBE of dilute-nitride optoelectronic devices

Molecular beam epitaxy of dilute-nitride materials has progressed a long way towards claiming its unique place as a key technology, which enables the development of new types of optoelectronics devices. This chapter begins by reviewing the technological particularities related to incorporation of nitrogen into III–V materials when using plasma-assisted molecular beam epitaxy. We then focus on describing the interplay between the growth parameters and nitrogen incorporation processes in dilute-nitride arsenides (III-N–As). Emphasis is laid on nitrogen-related growth kinetics that is accompanied by various bonding configurations and formation of several types of defects. An overview is provided also for dilute-nitride antimonides (III-N–Sb) and dilute-nitride phosphides (III-N–P). Finally, we review the growth optimisation and properties of several classes of dilute-nitride heterostructures for optoelectronics. These include uncooled long-wavelength laser diodes, SESAMs, VECSELs, enabling yellow emission by frequency doubling, and high-efficiency multijunction solar cells for concentrated photovoltaic systems