Switchable dual-wavelength erbium-doped fiber laser based on the photonic crystal fiber loop mirror and chirped fiber Bragg grating

Abstract

The switchable dual-wavelength erbium-doped fiber laser (EDFL) with a two-mode photonic crystal fiber (PCF) loop mirror and a chirped fiber Bragg grating (CFBG) at room temperature is proposed and experimentally demonstrated. The two-mode PCF loop mirror is formed by inserting a piece of two-mode PCF into a Sagnac loop mirror, with the air-holes of the PCF intentionally collapsing at the splices. By adjusting the state of the polarization controller (PC) appropriately, the laser can be switched between the stable single-and dual-wavelength operations by means of the polarization hole burning (PHB) and spectral hole burning (SHB) effects.Multi-wavelength fiber lasers have attracted considerable interest due to their potential applications in optical wavelength division multiplexed (WDM) systems, fiber sensor systems, optical devices testing, microwave photonics and so on. However, it is difficult to obtain the stable multi-wavelength output at room temperature in erbium-doped fiber lasers (EDFLs) because of the mode competition induced by the homogenous broadening and cross-gain saturation of the erbium-doped fiber. In order to achieve the stable multi-wavelength EDFLs at room temperature, various schemes have been proposed such as using the nonlinear polarization rotation of a highly nonlinear photonic crystal fiber [1] , adding a phase modulator [2] , introducing the saturated spectral hole burning (SHB) effect by the sampled FBG [3] and the polarization hole burning (PHB) effect by the FBGs in the fewmode fiber [4] , the FBG in the polarization maintaining fiber [5] , cascaded FBGs [6] , the sampled FBG [3] and the high-birefringence fiber loop mirror [7] .Owing to its flexible properties [8] , the photonic crystal fiber has been widely studied and offers a possibility to develop novel sensors, interferometers and other new applications. Recently, PCF interferometers based on a pair of longperiod fiber gratings or the tapering region have been proposed [9,10] . Experimental results indicated that PCF interferometers were suitable for sensing applications such as the external index and strain testing [11,12] . Due to their wavelengthdependent characteristics, PCF interferometers also can be used as the wavelength-selective filter.In this paper, a room-temperature switchable dual-wavelength fiber laser is demonstrated with a homemade two-mode photonic crystal fiber loop mirror (PCFLM) and a chirped fiber Bragg grating (CFBG). The PCFLM and CFBG are combined as wavelength-selective filters in the laser cavity. The laser has the advantages of simplicity and flexibility. It can operate in stable single-and dual-wavelength lasing oscillations by adjusting the polarization controller.When a two-mode PCF and a single-mode fiber (SMF) are spliced with a commercial fusion splicer, the air holes of the PCF inevitably collapse at the splices. When the fundamental mode in the SMF enters the PCF through the first collapsing region, it begins to be diffracted and excites the fundamental and higher-order modes in the two-mod...

All-fiber lasers through photonic crystal fibers

“…There are, however, other multiwavelength fiber lasers for which the laser configuration is based in a fiber loop mirror structure: using a fiber loop mirror to accommodate an erbium-doped medium and a Hi-Bi PCF to obtain a multiwavelength erbium-doped fiber laser [124] or using a fiber loop mirror to accommodate Raman gain, multiple Rayleigh scattering and a Hi-Bi PCF in order to accomplish a double random mirror multiwavelength fiber laser [125]. A switchable dual-wavelength erbium-doped fiber laser was developed using a two-mode photonic crystal fiber loop mirror [126].…”

Switchable multiwavelength erbium-doped photonic crystal fiber ring laser based on a length of polarization-maintaining photonic crystal fiber

“…They were employed in wavelength-switchable fiber lasers by a length of highly nonlinear photonic crystal fiber(HNL-PCF) and a multimode fiber Bragg grating (MM-FBG) [10] , or a length of HNL-PCF and a sampled chirped fiber Bragg grating (SC-FBG) [11] , or a sampled high-birefringence fiber grating and a PCF loop mirror [12] , or a Raman pump source and a PM-PCF-based Sagnac filter [13] , or a PCF loop mirror and a chirped FBG [14] .…”