Sub-50  fs pulse generation from a SESAM mode-locked Tm,Ho-codoped calcium aluminate laser

Abstract

We report on sub-50 fs pulse generation from a passively mode-locked (ML) Tm,Ho-codoped crystalline laser operating in a 2 µm spectral region. A T m , H o : C a ( G d , L u ) A l O 4 laser delivers pulses as short as 46 fs at 2033 nm with an average power of 121 mW at a pulse repetition rate of ∼ 78 M H z employing a semiconductor saturable absorber mirror as a saturable absorber. To the best of our knowledge, this result represents the shortest pulses ever generated from a Tm- and/or Ho-based solid-state laser. Polarization switching in the anisotropic gain material is observed in the ML regime without any polarization selection elements which is essential for the shortest pulses.

Achievements and Future Perspectives of the Trivalent Thulium-Ion-Doped Mixed-Sesquioxide Ceramics for Laser Applications

“…The point is that the gain profiles of Tm 3+ and Ho 3+ in co-doped hosts have overlapping regions, and it is possible to combine stimulated emissions of both active ions for ultrashort-pulse lasing. For instance, Wang et al [ 44 ] demonstrated 46 fs pulses at 2033 nm from an SESAM mode-locked Tm,Ho:Ca(Gd,Lu)AlO 4 laser, which is the shortest duration ever obtained in a Tm- and/or Ho-based gain medium. The aspect of optimal ratio between Tm and Ho ions in sesquioxides—and especially in mixed sesquioxides—needs detailed investigation.…”

“…As many applications require laser emission at longer wavelengths—as will be clarified later on—some crystals [ 36 , 37 , 38 , 39 , 40 , 41 , 42 ] and mixed ceramics have attracted the interest of the scientific community because they are characterized by slightly broader and smoother gain spectra, which can be exploited in developing tunable and sub-100 fs laser systems [ 43 , 44 , 45 ].…”

High-power modelocked thin-disk oscillators as potential technology for high-rate material processing

“…This latest progress shows that currently, Ho-doped materials appear to be the most promising for high-power ultrafast TDL operation, see Figure 5 . Too much Tm ions with respect to other potential Ho-doped materials for the thin-disk geometry, most ultrafast bulk oscillators were accomplished by codoping with Tm ions [ 94 ], which can then be diode-pumped via the Tm ions and broader bandwidths can be exploited as their single ion counterparts, reaching pulse durations as short as sub-50 fs with an average output power of 121 mW [ 107 ]. However, Tm, Ho codoping method adds an additional degree of freedom which is the ratio between the Tm and Ho ions, which strongly affects lasing operation and depends on the host material, and therefore needs more detailed investigation before being attempted in the more complex thin-disk geometry.…”

CH3NH3PbI3 Perovskite Nanorods Saturable Absorber for Stable Ultra-Fast Laser

“…Compared to active mode locking, passive mode locking can obtain pluses with narrower width and higher quality without adding complex active modulator components in resonator of the lasers, and is also more simple and cheaper to operate. Saturable absorber (SA) is a core element to achieve passive mode locking, where its performance directly affects stability of the mode-locking state and optical parameters of the output pulse [1][2][3]. Different types of saturable absorbers have been developed and used in lasers, where the most typically researched saturable absorber is the semiconductor saturable absorption mirrors (SESAM), for their suitable saturated absorption characteristics and modulation depth.…”