Ultrasensitive nonlinear absorption response of large-size topological insulator and application in low-threshold bulk pulsed lasers

Abstract

Dirac-like topological insulators have attracted strong interest in optoelectronic application because of their unusual and startling properties. Here we report for the first time that the pure topological insulator Bi2Te3 exhibited a naturally ultrasensitive nonlinear absorption response to photoexcitation. The Bi2Te3 sheets with lateral size up to a few micrometers showed extremely low saturation absorption intensities of only 1.1 W/cm2 at 1.0 and 1.3 μm, respectively. Benefiting from this sensitive response, a Q-switching pulsed laser was achieved in a 1.0 μm Nd:YVO4 laser where the threshold absorbed pump power was only 31 mW. This is the lowest threshold in Q-switched solid-state bulk lasers to the best of our knowledge. A pulse duration of 97 ns was observed with an average power of 26.1 mW. A Q-switched laser at 1.3 μm was also realized with a pulse duration as short as 93 ns. Moreover, the mode locking operation was demonstrated. These results strongly exhibit that Bi2Te3 is a promising optical device for constructing broadband, miniature and integrated high-energy pulsed laser systems with low power consumption. Our work clearly points out a significantly potential avenue for the development of two-dimensional-material-based broadband ultrasensitive photodetector and other optoelectronic devices.

Ultra-broadband Nonlinear Saturable Absorption for Two-dimensional Bi2TexSe3−x Nanosheets

“…According to previous reports27, for TI nanosheets, the larger the subsurface bulk region, the more sensitive the absorption is to the excitation intensity. For our results in Fig.…”

“…demonstrated a series realization of ultra-short pulse generation based on a Bi 2 Se 3 saturable absorber. Subsequently, similar work on other members of the Bi 2 Te x Se 3−x family, i.e., Bi 2 Te 3 , Bi 2 TeSe 2 , and Bi 2 Te 2 Se2425262728, was reported. However, those works generally focused on the modulation depth, saturation intensity and nonsaturable loss.…”

High-quality and Large-size Topological Insulator Bi2Te3-Gold Saturable Absorber Mirror for Mode-Locking Fiber Laser

“…51, is about 19 MW/cm 2 , which is comparable with I sat  = 26.7 MW/cm 2 for the Bi 2 Te 3 film deposited on microfiber by PLD57 but it is much less than 180 MW/cm 2 and 4.6 GW/cm 2 for Bi 2 Te 3 -nanosheets and Bi 2 Te 3 -nanoplates in refs 36 and 37, respectively. The large variation of saturation intensity could be due to that they are strongly dependent on the morphology and size (surface-to-volume ratio) of the Bi 2 Te 3 3758.…”

Dynamic cavity effects in topological insulator Bi2Te3 based passive Q-switched solid state laser

“…These bulk states with narrow direct bandgap grant the quasi-2D layered semiconducting material strong absorption [32]. We can accordingly understand that the absorption of narrow bandgap bulk state will be first saturated with low saturation intensity [33]. Furthermore, it is also worth to mention that from discussions above, the low-saturation intensity in TI-based SA limited the pulsation capability not only for high energy pulse formation [27] but also the QS-ML operation observed in PQS lasers under very strong pumping [34].…”