Fig. 1. Schematic of the phase-stable transmission system; the inset is an integrated phase-stable transmission system and the actual layout of the link. DRO, dielectric-resonant oscillator; OCXO, oven-controlled crystal oscillator; PID, proportional-integral-differential; OC, optical coupler; PD, photodetector; EDFA, erbium-doped fiber amplifier; OF, optical filter; LPF, low-pass filter.

Fig. 2. (a) Schematic of two-section analog DML; the inset is a picture of the analog DML chip after packaging and in use. (b) P-I curves of the two-section analog DML; (c) modulation amplitude response of the two-section analog DML when I_RS = 0 mA; (d) modulation amplitude response of the two-section analog DML when I_LS = 140 mA.

Fig. 3. (a) Measured V_IF in the phase-stable transmission system; (b) 50 km fiber link delay variation before and after compensation.

Fig. 4. (a) Phase noise of the frequency signal through 50 km fiber link (black, original Rb atomic clock; red, free running; blue, phase-locked). Temperature monitoring of the temperature control box. (b) Constant temperature; (c) variable temperature; (d) fractional frequency instability of the 50 km free-running link (gray pentagons); compensated link at 100 MHz when applying current to RS or not (green circles/red squares), and compensated link during temperature fluctuations (golden triangles) versus averaging time.