Fig. 1. Fabrication methods of two-dimensional heterostructure saturable absorbers.
Fig. 2. (a) Schematic of α-MoTe
2/MoS
2 heterostructure prepared by mechanical exfoliation
[40]; (b) the optical microscopy image
[40].
Fig. 3. (a) Illustration of preparation procedures of WS
2/Graphene heterostructure films by liquid phase exfoliation, a series of of WS
2/Graphene heterostructure films with different thickness obtained from different filtration volume; (b) atomic force microscopy image of WS
2/Graphene heterostructure films; (c) X-ray diffraction patterns; (d) absorption as a function of filtration volume at 800 nm; (e) open-aperture Z-scan results of WS
2, Graphene, and WS
2/Graphene heterostructure films with the thickness of ~135 nm; (f) histogram of the imaginary part of the third-order nonlinear coefficient Im
χ(3) and figure of merit (FOM) of WS
2, Graphene, and WS
2/Graphene heterostructure
[41].
Fig. 4. (a) Illustration of preparation procedures of MoTe
2/MoS
2 heterostructure films by liquid phase exfoliation; (b) Z-scan results of MoTe
2, MoS
2 and MoTe
2/MoS
2 heterostructure films under the pump intensity of 606 GW·cm
–2 with the thickness of ~80 nm; (c) Z-scan results of MoTe
2/MoS
2 heterostructure films with thickness of 30, 60, 80, 100, 120 nm at 606 GW·cm
–2, respectively
[47].
Fig. 5. (a) Schematic and (b) Raman spectrum of MoS
2/WS
2 heterostructure
[53]; (c) optical microscope photograph of monolayer triangular WS
2 grown on monolayer MoS
2 nanosheet; (d) photoluminescence (PL) spectrum of WS
2 monolayer, MoS
2 monolayer and MoS
2/WS
2 heterostructure
[54]; (e) schematic diagram of as-grown Bi
2Te
3/Graphene heterostructure on SiO
2/Si substrate; (f) absorption spectrum of Graphene and Bi
2Te
3/Graphene heterostructure
[55].
Fig. 6. (a) AFM image of Bi
2Te
3/Graphene heterostructure fabricated by two-step CVD method on the SiO
2 substrate; (b) thickness profiles along line 1 in (a); (c) absorption spectrum of Bi
2Te
3/Graphene heterostructure from 900−2000 nm
[56]; (d) schematic of WS
2/ Graphene heterostructure after transferring successfully; (e) Z-scan graph of WS
2, Graphene and WS
2/Graphene heterostructure
[32] Fig. 7. Scanning electron microscope images of MoS
2/WS
2 heterostructure from the top view (a) and side view (b); (c) Raman spectrum of MoS
2, WS
2 and MoS
2/WS
2 heterostructure; (d) transmission of MoS
2/WS
2 heterostructure with respect to the power intensity of incident light
[57].
Fig. 8. (a) Illustration of band alignment and carrier mobility of the type-II MoS
2/WS
2 heterostructure
[63]; (b) band alignment of semiconductor type-II MoTe
2/MoS
2 heterostructure
[47]; (c) diagram of the charge-transfer process in a MoS
2/graphene heterostructure
[64]; (d) energy band diagram of Bi
2Te
3/graphene heterojunction, the blue dots stand for the photogenerated electrons, while red hollow dots stand for holes
[55].
Fig. 9. Recorded results of Te/BP heterojunction SAM-based mode-locked laser: (a), (b) measured autocorrelation trace of 404 fs and the corresponding spectrum; (c), (d) recorded frequency spectrum with a wide and a narrow span respectively
[65]; (e) schematic setup of the
Q-switched mode-locking (QML) laser and (f) the output power versus pump power of the continuous wave (CW) and QML operation for MoS
2/Graphene heterostructure
[34] Fig. 10. (a) Schematic of graphene/MoS
2 heterojunction mode-locked laser device; (b) pulse trains; (c) spectrum; (d) autocorrelation race for 92 fs duration; (e) frequency spectrum
[66].
Fig. 11. (a)−(c) Mode-locking performance of Graphene/WS
2 heterostructure: (a) Optical spectrum; (b) pulse trains; (c) autocorrelation trace
[69]. (d)−(f) Mode-locking performance of Graphene/Mo
2C heterostructure: (d) Optical spectrum; (e) pulse trains; (f) autocorrelation trace
[70]. (g)−(i) Mode-locking performance of Graphene/phosphorene heterostructure: (g) Optical spectrum; (h) pulse trains; (i) autocorrelation trace
[71].
Fig. 12. (a) Schematic of Graphene/Bi
2Te
3 heterostructure on the end-facet of fiber connector; (b)−(d) Mode-locking characteristics of Graphene/Bi
2Te
3 heterostructure: (b) Optical spectrum; (c) pulse trains; (d) autocorrelation trace
[72]. (e) Schematic of Er-doped fiber laser. (f)−(h) Mode-locking characteristics of Bi
2Te
3/FeTe
2 heterostructure: (f) Optical spectrum; (g) pulse trains; (h) autocorrelation trace
[73]. (i) Schematic of Er-doped fiber laser. (j)−(l) Mode-locking characteristics of Graphene/MoS
2 heterostructure: (j) Optical spectrum; (k) pulse trains; (l) autocorrelation trace
[74].
Fig. 13. (a) Experimental setup of mode-locked fiber laser with 1550 nm QD-SESAM; Inset: cross-sectional transmission electron microscope image of the QD-SESAM and 1 μm × 1 μm AFM image of the 1550 nm QDs. (b)−(e) Characteristics of mode-locked the developed fiber laser of InAs/GaAs QD: (b) Output power versus pump power; (c) output optical spectra; (d) RF spectrum of the mode-locked fiber laser; (e) autocorrelation trace
[75].
Fig. 14. (a) Schematic of deposition of the Te/Se sample on the microfiber. (b)−(d) Mode locking performance of the Te-based fiber laser: (b) Optical spectrum; (c) pulse trains; (d) autocorrelation trace. (e) Te/Se samples under microscope with 50 μm scale. (f)−(h) Self-starting mode locking performance of the Yb-doped fiber laser: (f) Optical spectrum; (g) pulse trains; (h) autocorrelation trace
[76].
Fig. 15. (a)−(c) Mode-locking performance of MoS
2/WS
2 heterostructure: (a) Optical spectrum; (b) pulse trains; (c) autocorrelation trace
[57]. (d)−(f) Mode-locking performance of MoS
2/Sb
2Te
3/MoS
2 heterostructure: (d) Optical spectrum; (e) pulse trains; (f) autocorrelation trace
[77]. (g)−(i) Mode-locking performance of WS
2/MoS
2/WS
2 heterostructure: (g) Optical spectrum; (h) RF spectrum; (i) autocorrelation trace
[63].
Material type | Type of Laser | Fabrication method | λ/nm
| Pulse width | Repetition rate/MHz | Energy/nJ | Ref. | 注: SL, solid-state laser; FL, fiber laser; MBE, molecular beam epitaxy; FIBE, focused ion beam etching; LPE, liquid phase exfoliation; HM, hydrothermal method; CVD, chemical vapour deposition; SMD, selective metal deposition; MSD, magnetron sputtering deposition; SASR, self-assembly solvothermal route. | InAs/GaAs QDs | FL | MBE | 1556.00 | 920.00 fs | 8.16 | — | [75]
| GaN/InGaN | — | FIBE | 408.00 | 1.40 ps | 10.00 | | [78]
| 2D Te/BP | SL | LPE | 1049.10 | 404.00 fs | 42.10 | 6.9400 | [65]
| Te/Se | FL | HM | 1500.00 | 889.00 fs | 18.50 | — | [76]
| 1000.00 | 11.70 ps | 18.50 | Graphene/MoS2 | SL | LPE | 1061.56 | 306.00 ps | 83.30 | — | [34]
| Graphene/MoS2 | SL | LPE | 1063.00 | 92.00 fs | 84.75 | — | [66]
| Graphene/MoS2 | SL | CVD | 1037.20 | 236.00 fs | 41.84 | 19.0000 | [64]
| Graphene/MoS2 | FL | CVD | 1571.80 | 830.00 fs | 11.93 | — | [74]
| Graphene/MoS2 | FL | LPE HM | 1571.80 | 2.20 ps | 3.47 | — | [68]
| Graphene/WS2 | FL | CVD | 1593.50 | 55.60 ps | 3.63 | — | [79]
| Graphene/WS2 | FL | CVD | 1568.30 | 1.12 ps | 8.83 | 0.5400 | [69]
| Graphene/WS2 | FL | LPE | 1066.20 | 450.00 ps | 19.68 | 0.1108 | [80]
| Graphene/Mo2C
| FL | CVD | 1599.00 | 723.00 fs | 15.33 | 0.7130 | [70]
| Graphene/BP | FL | LPE | 1529.92 | 820.00 fs | 7.43 | — | [71]
| 1531.00 | 148.00 fs | 7.50 | Graphene/Bi2Te3 | FL | CVD | 1565.60 | 1.80 ps | 6.91 | — | [56]
| 1049.10 | 144.30 ps | 3.70 | Graphene/Bi2Te3 | FL | CVD | 1568.07 | 837.00 fs | 17.30 | 0.1780 | [72]
| Graphene/Bi2Te3 | FL | CVD | 1058.90 | 189.94 ps | 79.13 | — | [81]
| Bi2Te3/FeTe2 | FL | SMD | 1064.00 | 164.70 ps | 15.02 | — | [73]
| 1550.00 | 481.00 fs | 23.00 | MoS2/graphene/WS2 | FL | CVD | 1567.51 | — | 2.10 | — | [82]
| MoS2/WS2 | FL | MSD | 1560.00 | 154.00 fs | 74.60 | — | [57]
| WS2/MoS2/WS2 | FL | MSD | 1562.66 | 296.00 fs | 36.46 | — | [63]
| MoS2/Sb2Te3/MoS2 | FL | MSD | 1554.00 | 286.00 fs | 36.40 | — | [77]
|
|
Table 1. [in Chinese]