Polarization controlled multiwavelength switchable erbium-doped fiber laser based on high birefringence few-mode fiber loop mirror

A multiwavelength switchable erbium-doped fiber laser with linear cavity is proposed and experimentally demonstrated. It is based on a fiber loop mirror incorporating a piece of high birefringence few-mode fiber and polarization controller. Due to dependence of its reflection properties on the polarization controllers, the fiber laser can operate in the random combination of three wavelengths by only adjusting the polarization controllers in the linear cavity. The wavelengths involved in the switching operation are determined by the merged Sagnac and intermodal interferences elicited in the fiber loop mirror. The optical signal to noise extinction ratio of every oscillation line is higher than 40 dB and power fluctuation less than 0.5 dB.     

Broadly tunable dual-wavelength erbium-doped ring fiber laser based on a high-birefringence fiber loop mirror

A broadly tunable dual-wavelength erbium-doped ring fiber laser based on a high-birefringence fiber loop mirror (HiBi-FLM) and a polarization controller is demonstrated experimentally. The measured transmission spectrum of HiBi-FLM covers a wide range from 1525 to 1575 nm. The wavelength of proposed laser can be flexibly tunable during this range of ∼50 nm by adjusting the polarization controller. In addition, the spacing of two wavelengths is adjustable by changing the length of HiBi fiber. The dual-wavelength lasers with the HiBi fiber length of 1 and 2 m are experimentally demonstrated and compared. The experimental results show that the proposed laser can stably operate on two wavelengths simultaneously at room temperature, and the output peak power variation is about 0.5 dB during 40 min.     

Switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating few-mode high birefringence fiber

Without the need of any other additional filtering device, a triple-wavelength switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating a piece of few-mode high birefringence fiber is newly proposed and experimentally demonstrated. Three potential lasing wavelengths at about 2.0 nm interval with the side mode suppression ratio higher than 40 dB can be switched mainly by adjusting a polarization controller next to the few-mode high birefringence fiber in the Sagnac loop. In addition to the stable single-line lasing operation, simultaneous dual- and triple-line oscillations are also highly stable at room temperature with suppressing the intrinsic homogeneous gain broadening of the erbium-doped fiber.     

基于FLM的L波段双波长EDFL的双稳态变换

提出和验证了一种L波段双波长掺铒光纤激光器(EDFL)双稳态控制变换和双波长开关切换的方法.将偏振控制器(PC)插入基于3 dB光纤耦合器的光纤环镜(FLM)中，并将该FLM用作L波段双波长级联线形耦合腔EDFL的公共腔镜，结果表明，调节PC可以改变FLM的反射率，实现对EDFL双稳态特性的有效控制，且双稳态特性随FLM反射率呈单调变化.利用这一性质，提出并证实，对于处在FLM最大反射率对应的双稳态第一跃变点和最小反射率对应的双稳态第二跃变点之间的任意固定抽运光功率，调节PC可实现两个稳态之间的相互变换和双波长之间的相互切换.     

Waveband switchable multi-wavelength erbium-doped fiber ring laser based on wavelength-dependent polarization rotation mechanism

A waveband switchable multi-wavelength erbium-doped fiber ring laser based on wavelength-dependent polarization rotation mechanism and birefringence-based in-line comb filter is proposed and demonstrated. The two lasing wavebands, around 1530 and 1560 nm region, can be efficiently switched by simply rotating the polarization controllers (PCs). The channel spacing is 0.4 nm which was determined by the length of polarization maintain fiber (PMF) used in the experiment. The experimental results show that the waveband switchable is an intrinsic feature of multi-wavelength fiber ring lasers by incorporating a passive polarizer in the laser cavity.     

Tunable multi-wavelength fiber ring laser based on a Hi-Bi fiber loop mirror

A novel tunable multi-wavelength fiber ring laser based on semiconductor optical amplifier(SOA)is proposed by using a high-birefringence(Hi-Bi)fiber loop mirror(FLM)as wavelength filter.With this configuration,the wavelength spacing of this laser can be varied by using the different lengths of Hi-Bi fiber.8 wavelengths spacing on 450 GHz are experimentally obtained with more than 25-dB signal-to-noise ratio(SNR)for each channel using 1.28-m Hi-Bi fiber in Hi-Bi FLM.The output power variation between different channels is measured to be less than 5.9 dB.The linewidth of each channel is compressed from 0.347 to 0.186 nm by 1.5-m unpumped erbium-doped fiber(EDF).Meanwhile,17 wavelengths spacing on ITU-gird(100 GHz)are also obtained with 5.9-m Hi-Bi fiber in Hi-Bi FLM.All these channels can be tuned together over 0.4 nm.     

Dual-wavelength S-band erbium-doped fiber double-ring laser

We propose and demonstrate an S-band CW dual-wavelength erbium-doped fiber (EDF) dual-ring laser using a compound-ring filter (CRF) with various coupling losses inside the gain cavity. Employing a ring filter combined within the cavity, the fiber laser can lase a dual wavelength without any filter inside the ring loop. The dual-wavelength output exhibits a good performance having optical side-mode suppression ratios (SMSRs) of 31.6 and 31.8 dB and output powers of ?9.6 and ?9.3 dBm at 1505.58 and 1506.43 nm, respectively, when the coupling loss is 30% inside the cavity. In addition, the output stabilities of the dual-wavelength laser have also been analyzed.     

Multiwavelength erbium-doped fiber laser employing a nonlinear optical loop mirror

A stable and broad bandwidth multiwavelength erbium-doped fiber laser is proposed and demonstrated successfully. A nonlinear optical loop mirror which induces wavelength-dependent cavity loss and behaves as an amplitude equalizer is employed to ensure stable room-temperature multiwavelength operation. Up to 50 wavelengths lasing oscillations with wavelength spacing of 0.8 nm within a 3-dB spectral range of 1562-1605 nm has been achieved. The measured power fluctuation of each wavelength is about 0.1 dB within a 2-h period.     

A novel double-Brillouin-frequency spaced multi-wavelength Brillouin erbium-doped fiber laser based on non-linear amplified fiber loop mirror

In the paper, a ring double-Brillouin-frequency spaced multi-wavelength Brillouin erbium-doped fiber laser based on non-linear amplified fiber loop mirror filter is demonstrated, in which the non-linear amplified fiber loop mirror (AFLMF) is used as a filter. At the 980 nm pump power of 10.29 dBm, the tunable laser source center wavelength of 1563 nm and power of −3 dBm, up to 12 even output channels with 0.16 nm spacing are achieved. At the same time, we study the influence of 980 nm pump power, the polarization controller and the tunable laser source center wavelength on the number of Stokes light wave.     

Dual-wavelength narrow-linewidth fiber laser based on F-P fiber ring filter

A dual-wavelength fiber laser with a narrow-linewidth, based on a P-F fiber filter has been proposed. Polarization-maintaining fiber Bragg grating (PM-FBG) and a F-P fiber filter are introduced based on the traditional fiber laser. PM-FBG is used as the wavelength selection device. The fiber F-P filter consists of two optical couplers and a section of un-pumped erbium-doped fiber (EDF). Due to the delay of cavity and the loss generated by the EDF, the filter has comb spectral response. The incorporation of the fiber F-P filter leads to the suppression of undesirable modes. At the room temperature, under 980 nm LD pumped, the maximum output of the two wavelengths is respectively ?2.259 dBm and 0.568 dBm, with the 3-dB bandwidth separately 0.1 nm and 0.14 nm, realizing the narrow linewidth and dual-wavelength output.     

Wavelength-tunable erbium-doped fiber laser with FBG and HiBi fiber loop mirror as reflectors

In this paper, a novel structure erbium-doped fiber laser with a linear cavity is demonstrated. The wavelength selective devices are a fiber Bragg grating (FBG) and a high birefringence (HiBi) fiber loop mirror. From 1543.8 to 1555.2 nm, 15 lasering wavelengths with side mode suppresion ratio (SMSR) ＞ 54dB and approximately 0.8-nm spacing have been obtained by using the comb-like reflection spectrum of fiber loop mirror and the intensity reaches about 2.5 dBm on an average. The reflectivity at different wavelengths can be tuned with different settings of polarization controller and the relative laser intensity can be controlled over a dynamic range of 13.5 dB.     

Chaotic dynamics of erbium-doped fiber laser with nonlinear optical loop mirror

We experimentally and numerically demonstrate the chaotic dynamics of the erbium-doped fiber laser with a nonlinear optical loop mirror. When the polarization controllers are fixed at an appropriate orientation, we observe that the fiber laser exhibits a period-doubling route to chaos with increasing the pump power in the experiment and simulation. The numerical simulation shows a good agreement with the experimental results. The results show experimentally and numerically that the chaotic dynamics of the erbium-doped fiber laser is related to the polarization state and the pump power of light in the cavity.     

Stable dual-wavelength erbium-doped fiber ring laser with switchable spacing employing controllable channel loss

A stable dual-wavelength erbium-doped fiber ring laser with switchable spacing is proposed and experimentally demonstrated. An arrayed waveguide grating (AWG) incorporating two fiber optic switches (OS) is used to as the wavelength selector. The ring cavity is divided into two cavities by a 30:70 optical coupler. Equalized dual-wavelength outputs are achieved by controlling the variable optical attenuator (VOA) inserted in the lower loss cavity. The wavelength spacing can be tuned from 0.80 to 12.05 nm. The fiber laser has good optical quality with maximum power fluctuation of 1.5 dB and side mode suppression ratios (SMSRs) higher than 71 dB.     

Multi-wavelength hybrid gain fiber ring laser based on Raman and erbium-doped fiber

A stable and uniform multi-wavelength fiber laser based on the hybrid gain of a dispersion compensating fiber as the Raman gain medium and an erbium-doped fiber (EDF) is introduced. The gain competition effects in the fiber Raman amplification (FRA) and EDF amplification are analyzed and compared experimentaUy. The FRA gain mechanism can suppress the gain competition effectively and make the present multi-wavelength laser stable at room temperature. The hybrid gain medium can also increase the lasing bandwidth compared with a pure EDF laser, and improve the power conversion efficiency compared with a pure fiber Raman laser.     

基于高双折射Sagnac环的可调环形腔掺铒光纤激光器理论与实验研究

报道了一种利用偏振控制器（PC）和保偏光纤（PMF）组成的高双折射Sagnac干涉环实现选频和调谐的环形腔掺铒光纤激光器.理论模拟了PMF和PC对波长的控制作用.实验中调节PC得到了单波长、双波长和多波长激光;并验证了滤波间隔随PMF长度的变化规律.实验中得到了斜率效率20%,3 dB线宽0.016 nm,30 dB线宽0.097 nm,边模抑制比（SMSR）40 dB左右的稳定激光输出. 关键词： 光纤激光器 Sagnac干涉环 环形腔 掺铒光纤     

Switchable multi-wavelength erbium-doped fiber ring laser based on cascaded polarization maintaining fiber Bragg gratings in a Sagnac loop interferometer

A switchable multi-wavelength erbium-doped fiber (EDF) ring laser based on cascaded polarization maintaining fiber Bragg gratings (PMFBGs) in a Sagnac loop interferometer as the wavelength-selective filter at room temperature is proposed. Due to the polarization hole burning (PHB) enhanced by the PMFBGs, stable single-, dual-, three- and four-wavelength lasing operations can be obtained. The laser can be switched among the stable single-, dual-, three- and four-wavelength lasing operations by adjusting the polarization controllers (PCs). The optical signal-to-noise ratio (OSNR) is over 50 dB.     

Stable multi-wavelength erbium-doped fiber laser based on dispersion-shifted fiber and Sagnac loop filter

A multi-wavelength erbium-doped fiber laser (MEDFL) with simple line structure is experimentally demonstrated by using a Sagnac interferometer as a comb filter. It is shown that the multi-wavelength lasing is quite stable at room temperature due to the four-wave mixing (FWM) effect among different laser channels in the dispersion-shifted fiber cooperated in the laser cavity.     

Switchable multiple lasing oscillations in an erbium-doped fiber ring laser using a single stage of a Sagnac loop mirror

A simple scheme for a switchable multi-wavelength erbium-doped fiber (EDF) ring laser is investigated by using a single stage of a Sagnac loop mirror. The multiple lasing outputs are obtained and switched readily by controlling the state of polarization (SOP). Since the transmission characteristics of the Sagnac loop mirror in terms of peak wavelengths and peak powers strongly depend on the SOP, the switching performance of the proposed multi-wavelength EDF laser can be effectively obtained. The proposed multi-wavelength EDF laser has versatile lasing outputs in states of a single-, dual-, triple-, and quadruple-wavelength oscillations. The multiple outputs are effectively switchable by adjusting the SOP.     

Tunable multiwavelength SOA-fiber ring laser based on Sagnac loop mirror incorporating few-mode high birefringence fiber

A tunable multiwavelength fiber ring laser based on a semiconductor optical amplifier and Sagnac loop mirror incorporating a piece of few-mode high birefringence fiber (FM-HBF) is proposed and experimentally demonstrated. It is accomplished by simply adjusting a polarization controller in the Sagnac loop mirror because birefringence of the FM-HBF is polarization dependent. Tunable multiwavelength operation up to 11 oscillating lines at about 2.1 nm interval is stably achieved with an optical side-mode suppression ratio over 35 dB.