Fig. 1. Principle diagram of optical transmission of 45° tilted fiber grating

Fig. 2. Characteristics of 45° tilted fiber grating. (a) Polarization dependent loss; (b) insertion loss

Fig. 3. Fabrication of tapered fiber. (a) Structural diagram of tapered fiber; (b) diagram of tapering device; (c) microscopic image of waist zone

Fig. 4. Measurements of tapered fiber characteristics. (a) Experimental setup of transmission spectrum measurements of tapered fiber; (b) measurement results of insertion loss of tapered fiber (inset: optical transmission spectra before and after tapering)

Fig. 5. Experimental setup of wavelength-tunable passively mode-locked Erbium-doped fiber laser

Fig. 6. Performances of output pulse. (a) Oscillogram; (b) optical spectrum; (c) frequency spectrum; (d) autocorrelation curve

Fig. 7. Output characteristics versus displacements. (a) Pulse spectra under different displacements; (b) central wavelength versus displacement; (c) output power and insertion loss versus displacement

Fig. 8. Characteristics of tapered fiber and output versus displacement. (a) Insertion losses of tapered fiber under different displacements; (b) central wavelength versus insertion loss of tapered fiber

Fig. 9. Characteristics of output pulses with different central wavelengths. (a) Pulse energy and peak power versus output wavelength; (b) spectral width and pulse duration versus output wavelength