Fig. 1. (a) Internal schematic setup of the highly integrated optical device. EDF, erbium-doped fiber; SMF, single-mode fiber; G-lens, gradient-index lens; SA film, saturable absorber film; WDM slice, wavelength division multiplexer slice. (b) Image and size of the proposed optical device.

Fig. 2. (a) Schematic setup of nonlinear optical characterization. OC, optical coupler; OPM, optical power meter. (b) Image of SA film. (c) Nonlinear saturable absorption of the SA. The solid curve is the fit to the experimental data.

Fig. 3. Schematic setup of the ultracompact laser. EDF, erbium-doped fiber; the highly integrated optical device is marked with a red dashed rectangle box, and it is an aggregation of an SA, coupler, isolator, WDM, and EDF; LD, laser diode. The red arrow in the inner loop shows the propagation route of 980-nm light, while the blue arrow in the outer loop shows the propagation route of the 1550-nm CW and soliton.

Fig. 4. Typical characteristics of an ultrafast soliton. (a) Optical spectrum; (b) oscilloscope trace; (c) autocorrelation trace of the experimental data (circles) and sech2-shaped fit (solid curve); (d) fundamental RF spectrum.

Fig. 5. Characteristics of ultrafast CS. (a) Optical spectrum; (b) oscilloscope trace.