Fundamental and harmonic mode-locking at 21 μm with black phosphorus saturable absorber

Abstract

We report mode-locking in holmium-doped all-fiber laser based on black phosphorus saturable absorber. The generated solitons are centered at 2094 nm with bandwidth reaching 4.2 nm and pulse duration of 1.3 ps. In harmonic mode-locking, up to 10th harmonic (290 MHz) was obtained. Properties of black phosphorus saturable absorber are investigated. Our findings validate black phosphorus suitability for ultrafast applications in mid-infrared.

2D Layered Materials: Synthesis, Nonlinear Optical Properties, and Device Applications

“…Additionally, researchers from other groups also demonstrated the 2 µm mode‐locked lasers based on WS 2 SA and BP SA, respectively, as shown in Figure d–i. Up to now, 2 µm mode‐locked fiber lasers have been achieved with layered materials, such as graphene, Bi 2 Te 3 , MoS 2 , WS 2 , WTe 2 , WSe 2 , MoTe 2 , and BP, respectively. Among them, several important works should be emphasized, such as the maximum pulse energy of 35.2 nJ, the repetition rate of 58.87 MHz, and the minimum pulse width of 190 fs …”

“…For example, the researchers realized a 2-µm mode-locked fiber laser based on graphene SA, [333] as shown in Figure 12a-c. Additionally, researchers from other groups also demonstrated the 2 µm mode-locked lasers based on WS 2 SA [348] and BP SA, [352] respectively, as shown in Figure 12di. Up to now, 2 µm mode-locked fiber lasers have been achieved with layered materials, such as graphene, [333][334][335][336][337][338][339][340][341]344] Bi 2 Te 3 , [345,346] MoS 2 , [347] WS 2 , [348] WTe 2 , [349] WSe 2 , [350] MoTe 2 , [351] and BP, [352,353] respectively. Among them, several important works should be emphasized, such as the maximum pulse energy of 35.2 nJ, [335] the repetition rate of 58.87 MHz, [341] and the minimum pulse width of 190 fs.…”

Solution-processed two-dimensional materials for ultrafast fiber lasers (invited)

“…The most popular exfoliation method used to fabricate SAs is ultrasonication, in which ultrasound waves are employed to disrupt the weak inter-layer van der Waals forces within the 2D crystal ( Figure 1A, B). Ultrasonication has proved effective for most 2DM-based SAs, including graphene [36,41,[62][63][64][65][66][67]133], TIs [16, 59, 89, 91, 105, 107-111, 114, 136-138], TMDs [19, 39, 60, 74, 83-89, 91, 92, 96, 97, 99-104, 135, 139-142], and BP [42,[116][117][118][119][120][121][122][123][124][125][126][127][128][129][130][143][144][145]. Its popularity arises from the ease of use, low cost, and immediate availability across most laboratories [55,146,147].…”

BN as a Saturable Absorber for a Passively Mode‐Locked 2 µm Solid‐State Laser

“…Compared to traditional Q‐switched and mode‐locked technique, the passively Q‐switched (PQS) and passively mode‐locked techniques are a low‐cost and compact method to realize ultra‐short pulse lasers using 2D materials as SAs. Typical 2D materials such as graphene, black phosphorus (BP), transition metal dichalcogenides (TMDCs) can be used as the SAs of 2 µm waveband owing to their excellent optical nonlinearity, ultrafast recovery time, broadband saturable absorption characteristics, and easy fabrication . Graphene is a zero‐bandgap material with very good thermal conductivity and optical properties.…”

“…Typical 2D materials such as graphene, black phosphorus (BP), transition metal dichalcogenides (TMDCs) can be used as the SAs of 2 mm waveband owing to their excellent optical nonlinearity, ultrafast recovery time, broadband saturable absorption characteristics, and easy fabrication. [10][11][12][13][14] Graphene is a zero-bandgap material with very good thermal conductivity and optical properties. Pure non-defective single-layer graphene has thermal conductivity up to 5300 W mK À1 and its optical absorption is independent of optical frequency and conductivity constant.…”