Research On Tunable EDFL And Multiwavelength Fiber Lasers

Tunable laser and multiwavelength laser are key components in dense wavelength division multiplexing(DWDM) transmission systems. This dissertation is focused on tunable erbium-doped fiber laser(EDFL) and multiwavelength fiber laser, which include:1. The development of laser diode(LD) power1)Based on analog circuits, two LD power circuits with dual-switchable constant current sources in series are designed. The damage to the expensive LD caused by the sudden invalidation of one source can be avoided, thus saving the complex high speed protection circuit.2. Research on tunable EDFL1)A L-band erbium-doped fiber amplifier(EDFA) is designed in dual-stage. Gain-flattened amplified spontaneous emission(ASE) is obtained. And the 3dB bandwidth is about 40nm.2)A wavelength-tunable erbium-doped fiber laser in L band based on a tunable F-P filter is demonstrated. Single frequency laser can be tuned from 1574.56 to 1607.60nm.3)A wavelength-selectable discretely tunable erbium-doped fiber laser in L band is demonstrated by using a high birefringence fiber loop mirror(Hi-Bi FLM) as a precise multiwavelength grid filter. With a Hi-Bi FLM and an L-band channel-selecting tunable filter, 41 wavelengths spacing on 100GHz are obtained.3. Research on multiwavelength fiber laser1)We propose a novel switchable multiwavelength fiber ring laser base on SOA, which uses a Hi-Bi FLM as a filter. Simultaneous lasing of 17 wavelengths spacing on 100GHz are obtained. By adjusting the states of polarization controller(PC), these 17wavelengths can be tuned together over 50GHz.