A highly uniform multiwavelength erbium-doped fiber ring laser with an intracavity sine phase modulator is demonstrated. The flat output spectrum is achieved by optimizing the cavity structure, modulation amplitude, and frequency of the sine phase modulator. Fifteen lasing lines with wavelength spacing of 0.9 nm appear simultaneously and stably with power differences less than 2 dB and side-mode suppression ratio higher than 32 dB. In addition, the proposed cavity can support unidirectional operation without optical isolators. An output power difference of about 20 dB is realized between the counterclockwise and clockwise directions, which is almost independent of the pump power and lasing wavelengths.
Highly uniform multiwavelength erbium-doped fiber ring laser with a sinusoidal phase modulator and line intervals of 0.45 nm is demonstrated. The flat and stable output distribution is realized by optimizing modulation voltage and frequency for the sine phase modulator. Simultaneous 30 lasing lines are obtained in power difference less than 2 dB. In addition, the implemented cavity structure can support unidirectional operation even without optical isolators. The power difference between clockwise and counterclockwise direction is higher than 20 dB, almost independent of pumping powers and lasing wavelengths in lasing operation.
We propose using a novel multifunction optical filter with cascaded sagnac circuits for future smart wavelength division multiplexed
network system applications. The coupling coefficients of the couplers in cascaded sagnac circuits are apodized according to the
Gaussian function. By properly adjusting only two parameters, the coupling coefficients are convex-apodized or concave-apodized.
For the former, we can obtain passband filter and improve response functions such as flatness and steepness; for the latter, it is
possible to gain comb-like transmitted responses.