Institute of Electrical and Electronics Engineers, IEEE Photonics Technology Letters, 19(18), p. 2038-2040, 2006
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Four pi-phase shifts are introduced in a uniform fiber Bragg grating (FBG) structure to realize a quadruple-transmission-band filter with ultranarrow 40-pm wavelength spacing. Four separate single-wavelength lasings at 1552.60, 1552.63, 1552.67, and 1552.71 nm, and three pairs of dual-wavelength lasings among above four wavelengths, are achieved stably by incorporating the quadruple-transmission-band FBG filter in a fiber ring cavity with a tunable uniform FBG acting as coarse frequency selection. This new kind of laser will be very useful in applications requiring closely spaced and tunable single- or dual-wavelength components