Diode-pumped ultrafast Yb:KGW laser with 56 fs pulses and multi-100 kW peak power based on SESAM and Kerr-lens mode locking

Abstract

A high power sub-60 fs mode-locked diodepumped Yb:KGW laser based on hybrid action of an InGaAs quantum-dot saturable absorber mirror and Kerr-lens mode locking was demonstrated. The laser delivered a 56 fs pulse with 1.95 W of average power corresponding 450 kW of peak power. The width of the generated laser spectrum was 20.5 nm, which was near the gain bandwidth limit of the Yb:KGW crystal. To the best of our knowledge, these are the shortest pulses generated from the monoclinic double tungstate crystals (and Yb:KGW laser crystal in particular) and the most powerful in the sub-60 fs regime. At the same time, they are also the shortest pulses produced to date with the help of a quantum-dot-based saturable absorber. High power operation with a pulse duration of 90 fs and 2.85 W of average output power was also demonstrated.

InP/InGaP quantum-dot SESAM mode-locked Alexandrite laser

“…The autocorrelation trace of the pulses and the corresponding spectrum are displayed in figure 3(a) and figure 3(b), respectively. Furthermore, stable single-pulse mode locking and the absence of Q-switching instabilities were confirmed using a long scan range (200 ps) autocorrelator and a fast oscilloscope/photodetector with photodiode that had a combined resolution of ~100 ps [35,36]. Considering the repetition rate of ~80 MHz, 420 fs laser pulses had energy of ~4.1 nJ and peak power of >9.5 kW.…”

High power Nd:YVO-KGW conical refraction laser

“…The CR crystal was an 18 mm-long anti-reflection coated KGW crystal which was cut along its optical axis. KGW crystals are wellknown for the CR effect [38][39][40][41][42], have good optical quality [11] and are typically used as host for Nd-and Yb-ion lasers [43][44][45][46][47][48][49][50][51][52][53]. A photograph of the developed laser is shown in Fig.…”

Diode-pumped 45 fs Yb:CALGO laser oscillator with 17 MW of peak power

“…In this Letter, we demonstrate, to the best of our knowledge, the highest peak power ever achieved for any sub-50 fs diode-pumped Yb-doped lasers to date by exploiting the advantages of the Yb:CALGO crystal, efficient diode pumping, and the dual action of the Kerr-lens mode locking (KLM) and semiconductor saturable absorber mirror mode locking (SESAM). While KLM and SESAM are well-known techniques to generate ultrashort pulses on their own [8,[10][11][12]16,17], their combination offers the benefits of operation with both high output power and short pulse duration [14,[18][19][20]. As a result, the developed Yb:CALGO laser directly produced 45 fs long pulses with 1.7 MW of peak power.…”

“…The pump beam was imaged into the gain medium with the help of 50 and 75 mm focal length lenses, resulting in a spot size radius of about 85 μm. Figure 1 shows the laser cavity designed for mode locking (ML) based on the dual action of a Kerr-lens and saturable absorber (KLAS) mode locking [14,[19][20][21]. The radius of the laser mode in the gain medium was controlled by changing the distance (TR) from 255 to 275 mm.…”