Fig. 1. State-of-the-art SA devices using the heterostructure. (a) Schematic of macrostructure and (b) surface structure of the fabricated heterostructure SA. (7 nm thickness) is in the middle of (8 nm thickness). The gold film with 117 nm thickness is deposited on the polished fused silica substrate as a broadband reflection mirror. (c) SEM image of the surface of deposited heterostructure film. (d) SEM image of the film thickness.
Fig. 2. Atomic and electronic structures of the heterostructure. (a) Side and (b) top views of the heterostructure. In (b), the detailed matching pattern of the heterostructure is shown. The supercell is highlighted with yellow color, and the supercell is denoted by the blue area. (c) Unfolding band structure of the heterostructure. Here, the Fermi level is defined as zero. (d) Band alignment of the heterostructure. The corresponding energy levels of pure and slabs are shown in both sides.
Fig. 3. Standard two-arm transmission setup. The SAM is the heterostructure SA mirror.
Fig. 4. Characterization of the heterostructure SA mirror. (a) The modulation depth is 64.17%. (b) Raman spectrum of the heterostructure. (c), (d) Threshold damage condition of the heterostructure film at 12 mW.
Fig. 5. Configuration of the mode-locked EDF laser. WDM, wavelength-division multiplexer; LD, laser diode; SMF, single-mode fiber; EDF, erbium-doped fiber; OC, optical coupler; PC, polarization controller; PI-ISO, polarization-independent isolator; SAM, heterostructure SA mirror.
Fig. 6. Typical -switching characteristics. (a) -switched pulse trains. (b) Optical spectrum. (c) -switched pulse duration at 600 mW pump power. (d) RF spectrum at the fundamental frequency and wideband RF spectrum (inset).
Fig. 7. (a) Pulse duration and repetition rate versus incident pump power. (b) Average output power and single pulse energy versus incident pump power.
Fig. 8. Experimental results of fiber laser with mode-locked states. (a) Optical spectrum. (b) Pulse duration. (c) RF spectrum. (d) Phase noise.