SWCNT-SA mode-locked Tm:LuYO₃ ceramic laser delivering 8-optical-cycle pulses at 2.05  µm

Abstract

Passive mode locking of a T m : L u Y O 3 ceramic laser in the 2 µm spectral region is demonstrated by employing a single-walled carbon nanotube-saturable absorber. Almost chirp-free pulses as short as 57 fs, i.e., 8 optical cycles are produced at a repetition rate of 72.6 MHz (63 mW average power). The corresponding optical spectrum centered at 2045 nm, exhibits a bandwidth of 80 nm, which corresponds to almost chirp-free pulses. To the best of our knowledge, the results represent the shortest pulses generated by mode-locked Tm solid-state lasers.

Czochralski growth of mixed cubic sesquioxide crystals in the ternary system Lu2O3–Sc2O3–Y2O3

“…Recently, the fabrication (Lu et al, 2013;Liu et al, 2015;Thoř et al, 2021) and laser operation (Zhou et al, 2017;Jing et al, 2018;Hao et al, 2018;Toci et al, 2021) of mixed sesquioxides has drawn the attention of researchers. It was known that mixed sesquioxide ceramics provide ultrashort pulses in mode-locked operation (Zhao et al, 2020). Although high quality sesquioxide ceramics can be synthesized, their fabrication process is rather complicated, time consuming and often includes the use of foreign sintering aids such as ZrO 2 or LiF.…”

Power-scalable sub-100-fs Tm laser at 2.08 μm

“…Sub-100-fs ML operation of such a Tm 3+ -doped 'mixed' ceramic laser was first demonstrated in 2018: 63-fs pulses with an average power of only 34 mW were generated at 2057.2 nm employing a SESAM [15] . Subsequently, shorter pulse durations of 57 fs at 2045 nm and 54 fs at 2048 nm were reported using a single-walled carbon nanotube (SWCNT)-based SA and a SESAM, respectively, with average output power still below 100 mW [16,17] . Figure 1 summarizes the state of the art of sub-100-fs ML solid-state Tm lasers emitting in the 2-µm spectral range [16][17][18][19][20][21][22] .…”

“…Subsequently, shorter pulse durations of 57 fs at 2045 nm and 54 fs at 2048 nm were reported using a single-walled carbon nanotube (SWCNT)-based SA and a SESAM, respectively, with average output power still below 100 mW [16,17] . Figure 1 summarizes the state of the art of sub-100-fs ML solid-state Tm lasers emitting in the 2-µm spectral range [16][17][18][19][20][21][22] . An average power of 210 mW was demonstrated in 2019 with an SWCNT-SA ML Tm:LuYO 3 ceramic laser [16] .…”

“…Figure 1 summarizes the state of the art of sub-100-fs ML solid-state Tm lasers emitting in the 2-µm spectral range [16][17][18][19][20][21][22] . An average power of 210 mW was demonstrated in 2019 with an SWCNT-SA ML Tm:LuYO 3 ceramic laser [16] . In 2020, a slightly higher power of 222 mW was obtained from a Tm:Sc 2 O 3 laser using the KLM technique [21] , which represents the highest power ever reported Tm:(Lu,Y)2O3-SWCNT [16] Tm:(Lu,Y)2O3-SESAM [17] Tm:MgWO4-GSA [18] Tm:MgWO4-SWCNT [19] Tm:CLNGG-SWCNT [20] Tm:Sc2O3-KLM [21] Tm:CNNGG-SWCNT [22] This Work from such sub-100-fs ML solid-state Tm lasers.…”

“…An average power of 210 mW was demonstrated in 2019 with an SWCNT-SA ML Tm:LuYO 3 ceramic laser [16] . In 2020, a slightly higher power of 222 mW was obtained from a Tm:Sc 2 O 3 laser using the KLM technique [21] , which represents the highest power ever reported Tm:(Lu,Y)2O3-SWCNT [16] Tm:(Lu,Y)2O3-SESAM [17] Tm:MgWO4-GSA [18] Tm:MgWO4-SWCNT [19] Tm:CLNGG-SWCNT [20] Tm:Sc2O3-KLM [21] Tm:CNNGG-SWCNT [22] This Work from such sub-100-fs ML solid-state Tm lasers. One can recognize that all the average powers higher than 100 mW were obtained by using the above-mentioned sesquioxide materials [16,17,21] , and an obvious trade-off between average power and pulse duration can be seen from all these reported results.…”