Fig. 1. Schematic diagram of a 45°-TFG fiber laser frequency comb system. (a) Mode-locked fiber laser oscillator based on 45°-TFG; (b) pulse amplification; (c) octave supercontinuum spectrum generation and f-2f interferometer; (d) stabilization circuit of frep; (e) stabilization circuit of fceo

Fig. 2. Characterization of 45°-TFG. (a) Maximum and minimum transmission loss of 45°-TFG; (b) PDL and insertion loss of 45°-TFG

Fig. 3. Performances of a stretched-pulse mode-locked laser at 228 mW pump power. (a) Optical spectrum with logarithmic scale (violate) and normalized linear scale (orange); (b) AC traces of the compressed and direct output (inset) pulses, and corresponding Gaussian fits; (c) output pulse train; (d) RF spectra

Fig. 4. Output reliability and stability measurements of the oscillator. (a) Evolution of optical spectrum with pump power; (b) variation of output power and single pulse energy with pump power; (c) evolution of optical spectrum within 12 h; (d) evolution of output power within 12 h

Fig. 5. Characteristics of pulse amplification. (a) AC trace before amplifier; (b) variation of the output power of the amplifier with the pump power; (c) spectrum and (d) corresponding AC trace of the compressed pulse

Fig. 6. Spectra. (a) Full octave-spanning supercontinuum spectrum at the output of the HNLF; RF spectra of the fceo signal with RBW of (b) 100 kHz and (c) 3 kHz

Fig. 7. Stabilization of frep signal. (a)frep signal variation with PZT control voltage; (b) frequency fluctuation after frep signal stabilization;(c) Allan deviation curve after frep signal stabilization (normalized to frep signal)

Fig. 8. Stabilization of fceo signal. (a) fceo signal variation with pump current of oscillator; (b) RF spectrum of fceo/256 after stabilization; (c) frequency fluctuation after fceo/256 signal stabilization; (d) Allan deviation curve after fceo signal stabilization (normalized to 192 THz)

Fig. 9. Intensity noise distribution of 45°-TFG-based mode-locked fiber laser before and after stabilization