Fig. 1. Schematic diagram of the proposed polarization-maintained COEO incorporating a short length of unpumped EDF. EDFA, erbium-doped fiber amplifier; OC, optical coupler.

Fig. 2. (a) Electrical spectrum of the generated 10 GHz RF signal and (b) the eye diagram; (c) the optical spectrum and (d) the electrical spectrum of the generated optical pulses from the polarization-maintained COEO without incorporating an unpumped EDF.

Fig. 3. Electrical spectra of the generated 10 GHz RF signal from the polarization-maintained COEO incorporating a (a) 1, (b) 2, or (c) 4 m unpumped EDF with an absorption coefficient of 13 dB/m at 1530 nm.

Fig. 4. Electrical spectra of the optical pulses when a 1 m EDF with absorption coefficients of (a) 7, (b) 13, or (c) 22 dB/m at 1530 nm is inserted to fiber laser cavity.

Fig. 5. (Color online) (a) Eye diagram and (b) optical spectrum of the generated optical pulse when 1 m EDF with an absorption coefficient of 13 dB/m at 1530 nm is incorporated; (c) the phase noise of the generated RF signal from the OEO loop with and without the 1 m EDF with an absorption coefficient of 13 dB/m at 1530 nm.