Fig. 1. Schematic diagram of the proposed octave-spanning OFC generator. EDFA, erbium-doped fiber amplifier; OBPF, optical bandpass filter; CIR, optical circulator; HNLF, highly nonlinear fiber; PC, polarization controller; OC, optical coupler; FBG, fiber Bragg grating.

Fig. 2. (a) Output power and applied voltage versus injection current. (b) Lasing spectra map versus injection current. (c) Wavelength interval and intensity ratio of dual modes versus injection current. (d) Lasing spectrum at injection current of 46 mA.

Fig. 3. (a) Output spectra of 50 GHz spaced Brillouin OFCs before and after optical spectral filtering of two FBGs. (b) Measured autocorrelation traces of the optical pulse train before and after optical filtering of two FBGs.

Fig. 4. (a) Pulse width and pedestal intensity versus EDFA4 power. (b) Measured autocorrelation traces of optical pulses when the pump power is 550 mW. (c) Evolution of the optical spectrum versus EDFA4 power. (d) Optical spectrum of the octave-spanning OFC when pump power is 550 mW. The red line represents the dispersion of HNLF2. The dashed black curve is the simulated octave-spanning OFC spectrum. (e) Degree of coherence of the simulated spectrum.

Fig. 5. (a) Octave-spanning OFC spectra and (b) corresponding fine spectra around the pump light, using square microcavity lasers with lasing mode frequency intervals of 29, 50, and 65 GHz.

Fig. 6. (a) Electrical spectrum characteristic of the 29-GHz octave-spanning OFC and filtered OFC around 1310 nm. (b) Electrical spectrum within 2-MHz span of the octave-spanning OFC. (c) Electrical spectrum within 1.5-MHz span obtained from the filtered OFC around 1310 nm. (d) Relative intensity noise of the octave-spanning OFC.