Femtosecond Alexandrite laser passively mode-locked by an InP/InGaP quantum-dot saturable absorber

Abstract

An Alexandrite laser passively mode-locked using an InP/InGaP quantum-dot semiconductor saturable absorber mirror (QD-SESAM) was demonstrated. The laser was pumped at 532 nm and generated pulses as short as 380 fs at 775 nm with an average output power of 295 mW. To the best of our knowledge, this is the first report on a passively mode-locked femtosecond Alexandrite laser using a SESAM in general and a QD-SESAM in particular.

Graphene mode-locked femtosecond Alexandrite laser

“…In particular, Ghanbari et al reported the generation of femtosecond pulses from a Kerr-lens mode-locked (KLM) Alexandrite laser for the first time [18]. The same group later succeeded in producing 380 fs pulses at 775 nm by using an InP/InGaP quantum dot semiconductor saturable absorber mirror [19]. The shortest pulses of 70 fs duration were obtained from a multipass-cavity (MPC) KLM Alexandrite laser [20].…”

“…Several alternative saturable absorbers have been used at wavelengths below 800 nm, including graphene oxide [21], semiconductor saturable absorber mirrors (SESAMs) [22], single-walled carbon nanotubes [23], quantum dots (QDs) [19,24,25], and emerging two-dimensional (2D) materials [26][27][28]. Two-dimensional materials such as transition metaldoped dichalcogenides, black phosphorus, and topological insulators can provide strong absorption saturation but may also introduce a high level of nonsaturable loss [29][30][31], which is undesirable in a low-gain laser medium such as Alexandrite.…”

Temperature dependence of Alexandrite effective emission cross section and small signal gain over the 25-450 °C range

“…Over the last decade, the advancement of higher brightness laser and light-emitting diodes in the red spectral region, generated a renewed interest towards Alexandrite [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] and continuous-wave laser output powers above 25 W have already been achieved from compact diode-pumped systems [12]. Mode-locking of Alexandrite using Saturable Bragg Reflectors (SBRs) [26], Kerr-lensing [27,28], and graphene saturable absorbers [29] has also been demonstrated recently. Unlike simple laser systems such as Yb:YAG, Alexandrite has a complex energy level diagram ( Fig.…”

“…As a more specific example, over the last years, several groups have been working on the development of ultrashort pulse Alexandrite laser systems [26][27][28][29], which resulted in the generation of down to 70-fs long pulses with average output powers in the multi-mW to multi-100 mW range. Unfortunately, mode-locking is only demonstrated in systems pumped by complex green laser sources so far.…”

Diode-pumped alexandrite ring laser in single-longitudinal mode operation for atmospheric lidar measurements

“…Recently, with the advance of red diode laser technology, new investigations in the field of diode-pumped Alexandrite lasers have been conducted [11][12][13][14][15][16]. Other investigations on Alexandrite involve the usage of green lasers as pumping sources for generation of ultra-short pulses [17,18] and LED-pumped Alexandrite lasers [19].…”