Wavelength-Spacing-Tunable Double-Pumped Multiwavelength Optical Parametric Oscillator Based on a Mach–Zehnder Interferometer

A novel double-pumped ring cavity multiwavelength fiber optical parametric oscillator (MW-FOPO) with tunable wavelength spacing is proposed. In the MW-FOPO, we utilize a highly nonlinear dispersion-shifted fiber as the gain medium and a Mach-Zehnder interferometer as the comb-like filter. Twenty-four-wavelength lasing of the double-pumped MW-FOPO with a ripple less than ±4.3 dB and a wavelength spacing of about 0.8 nm in a wavelength range from 1541 to 1558 nm is experimentally demonstrated. The wavelength spacing can be continuously tuned and multiwavelength lasings with wavelength spacings of 0.08, 0.2, 0.4, and 0.8 nm are demonstrated, respectively. We discussed the power stability of the multiwavelength lasing of the double-pumped MW-FOPO. A comparison of the output spectra among the double-pumped MW-FOPO, the single-pumped MW-FOPO, and the multiwavelength erbium-doped fiber laser is also presented.