Fig. 1. Characterization of GR-BP SA. (a) SEM image. (b)–(d) EDS images of BP-GR on Si substrate. (e) HRTEM. (f) The SAED pattern from the rectangular region in (e). (g) AFM pattern. (h) The corresponding heights of the GR-BP sheets. (i) TEM image of the GR-BP sheets. (j) SAED pattern from the rectangular region in (i). (k) Absorption spectrum. (l) Raman spectra of GR/BP exposed in the air for 0 day. (m) Raman spectrum of BP in GR/BP in the air for 0 and 1 day. (n) Raman spectrum of pure BP exposed in the air for 0 and 1 day.

Fig. 2. Nonlinear optical response of the as-prepared GR-BP SAs. (a) Nonlinear transmission curve of GR-BP solution concentration A. (b) Nonlinear transmission curve of GR-BP solution concentration B.

Fig. 3. Configuration of the pulsed laser or ultrashort pulsed laser based on GR-BP.

Fig. 4. Characteristics of the Q-switched pulses. (a) Q-switching output spectrum. (b) Single pulse profile. (c) Output pulse train. (d) RF spectrum. (e) Output power and pulse energy as a function of the pump power, respectively. (f) Output repetition rate and pulse duration as a function of the pump power, respectively.

Fig. 5. Typical mode-locking characteristics. (a) Pulse train. (b) Optical spectrum. (c) Autocorrelation trace. (d) RF spectrum.

Fig. 6. Typical mode-locking characteristics. (a) Pulse train. (b) Optical spectrum. (c) Autocorrelation trace. (d) RF spectrum.

Fig. 7. Typical HML characteristics. (a) 21st of harmonics pulse train. (b) 28th of harmonics pulse train. (c) 40th of harmonics pulse train (d) Optical spectrum. (e) Autocorrelation trace. (f) RF spectrum.