Fig. 1. (a) Spectrum of F-P laser; (b) injection locking of F-P laser

Fig. 2. Vernier effect

Fig. 3. Experimental setup of tunable laser

Fig. 4. (a) Spectrum of F-P laser; (b) relationship between the driving current and the wavelength of maximum longitudinal mode of F-P laser

Fig. 5. (a) Relationship between the driving current and the wavelength of tunable laser; (b) 18 wavelengths of tunable laser

Fig. 6. Spectrum of tunable laser when wavelength is 1544.68 nm

Fig. 7. Diagram of switching time test unit in tunable lasers

Fig. 8. (a) Rising edge and (b) falling edge measured when tunable laser wavelength switches between 1535.2 nm and 1544.68 nm