Semiconductor saturable absorber mirror in the 3–5 µm mid-infrared region

Abstract

Semiconductor saturable absorber mirrors (SESAMs) have been regarded as a revolutionary technology for ultrafast mode-locked lasers, producing numerous landmark laser breakthroughs. However, the operating wavelength of existing SESAMs is limited to less than 3 µm. In this study, we create a 3–5 µm mid-infrared (MIR) SESAM by engineering an InAs/GaSb type-II superlattice. Bandgap engineering and the strong coupling between potential wells in a superlattice enable a broadband response of saturable absorption in the 3–5 µm spectral range. Using the fabricated SESAM, we realize a SESAM mode-locked Er:ZBLAN fiber laser at 3.5 µm, which delivers MIR ultrashort pulses with high long-term stability. The breakthrough of SESAM fabrication in the MIR will promote the development of MIR ultrafast coherent sources and related application fields.

Tunable and Robust Mid‐Infrared Saturable Absorber Employing Tungsten Doping Cadmium Oxide

“…The response time of CWO is comparable to that of InAs/GaSb SESAM (370 fs) and about 20 times faster than that of Yttrium‐doped CdO (6.54 ps). [ 20,55 ] It is also much faster than that of other 2D MIR materials, such as Bi 2 O 2 Se (≈3 ps) and graphene (1.27 ps) (Table 1). [ 17,56 ] Interestingly, the recovery time constant decreased as the W‐dopant level increased, which was associated with the higher density of trapping states induced by doping in the nanostructures.…”

“…The LIDT of the CdO‐SA is two orders of magnitude higher than that of commercially available SESAMs, and much better than that of previously reported semiconductor SAs (9.5 mJ cm −2 for InGaAs/GaAsP and 12 mJ cm −2 for InAs/GaSb). [ 55,57 ] Since the photon energy of 800 nm laser is much higher than that of MIR laser, the actual LIDT of the CdO film in the MIR band is expected to be higher. So it is reasonable to use the LIDT at 800 nm to reflect the excellent anti‐laser damage performance of CdO film at the MIR band.…”

Q-switched Er3+/Dy3+ codoped ZrF4 fiber laser: continuously tunable pulse generation from 3.06 to 3.62 µm

“…More importantly, the laser almost entirely covers the mid-IR strong absorption region of C-H bonds, thus providing a versatile tool (with further narrowed width by shortening fiber length and increasing SA modulation depth, and scaled power/energy based on an Er 3 =Dy 3 codoped ZrF 4 fiber amplifier) for real-world applications of gas lidar and polymer processing. In addition, this laser platform has been used to assess the long wavelength edges (in terms of pulse generation) of commercial InAs quantum-well-based SAs, showing the 3.39 μm longest Q-switching wavelength, despite the fact that the absorption edge of a recent home-made InAs superlattice-based SA has been extended to 5.4 μm [26] .…”

A corrugated epsilon-nearzero saturable absorber for a high-performance 1.3 μm solid-state bulk laser

“…The LIDT of CITO-SA is ∼60 mJ cm −2 , which much better than that of previously reported semiconductor SAs (9.5 mJ cm −2 for InGaAs/GaAsP and 12 mJ cm −2 for InAs/GaSb). 49,50 However, due to the influence of thermal effect, the current CITO-SA cannot withstand the longterm irradiation (>1 h) of high-power continuous laser. Subsequently, we will prepare a corrugated mask through nano-imprinting technology to replace the current SiO 2 microspheres, so as to improve its stability under continuous wave laser irradiation, and further improve the output performance of CITO-SA based pulsed lasers.…”