Fig. 1. Schematic diagram of the tunable and wavelength interval controlled EDFL using the proposed MZI filter.

Fig. 2. Schematic diagram of the proposed MZI filter composed of tapered fiber.

Fig. 3. Simulation of the transmission spectra of the MZI filter when the wavelength intervals are 1 nm, 0.7 nm, 0.5 nm, and 0.2 nm.

Fig. 4. Camera image of the taper platform and the taper fiber.

Fig. 5. Measurement of transmission of the MZI filter when the wavelength interval is (a) 1 nm, (b) 0.7 nm, (c) 0.5 nm, and (d) 0.2 nm.

Fig. 6. Principle of the cascading MZI filter and Sagnac filter.

Fig. 7. Spectra of the output wavelengths when the wavelength interval is 1 nm: (a) quadruple, (b) quintuple, (c) sextuple, and (d) septuple wavelengths.

Fig. 8. Tunable output spectra of the proposed EDFL: (a) quadruple, (b) quintuple, and (c) sextuple wavelengths.

Fig. 9. Spectra of the output wavelengths when the wavelength interval is 0.7 nm: (a) quintuple, (b) sextuple, (c) septuple, and (d) octuple wavelengths.

Fig. 10. Spectra of the output wavelengths when the wavelength interval is 0.5 nm: (a) sextuple, (b) septuple, and (c) octuple wavelengths.

Fig. 11. (a) Wavelength drift and (b) power fluctuation for each wavelength within 50 min.