Microwave generation using an all polarization-maintaining linear cavity dual-wavelength fiber laser with tunable wavelength spacing

A stable dual-wavelength erbium-doped fiber laser with a linear cavity is formed by a polarization-maintaining uniform fiber Bragg grating (PM-FBG) and a polarization-maintaining linearly chirped fiber Bragg grating (PM-LCFBG), both of which were fabricated on a high-birefringence (Hi-Bi) fiber. Experimental results show stable dual-wavelength lasing operation with a wavelength separation of ∼0.22 nm, which can be tuned down to as small as 0.05 nm and a large optical signal-to-noise ratio (OSNR) of over 40 dB under room-temperature. Microwave signal at frequency of 9.41, 18.03 and 27.46 GHz is achieved by heterodyned the output lasing wavelengths on a photodetector.     

Switchable dual-wavelength erbium-doped fiber-ring laser based on one polarization maintaining fiber Bragg grating in a Sagnac loop interferometer

A switchable erbium-doped fiber-ring laser providing dual-wavelength outputs with orthogonal polarizations when operating at room temperature is proposed. One polarization-maintaining fiber Bragg grating (PMFBG) in a Sagnac loop interferometer is used as the wavelength-selective filter. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The optical signal-to-noise ratio (OSNR) is over 42 dB. The amplitude variation over 90 min is less than 0.6 dB for both wavelengths.     

Tunable dual-wavelength fiber laser based on a single fiber Bragg grating in a Sagnac loop interferometer

We propose a simple dual-wavelength Er-doped fiber laser configuration based on a dual-wavelength fiber Bragg grating written on the splice joint between two different fibers for wavelength-selective filter in the Sagnac loop interferometer. The wavelength separation between the adjacent lasing wavelengths is 1.12 nm and the side-mode suppression ratio (SMSR) is over 55 dB. The output power variation is less than 0.8 dB over a two-minute period. Moreover, the lasing wavelength can be effectively tuned using the thermal heating method.     

Oscillation wavelength of fiber Bragg grating semiconductor lasers

Based on the physical fact that a laser containing a gain medium with homogenous line broadening oscillates at the wavelength which requires the smallest threshold gain due to the mode competition effect, after taking into account the wavelength-depended reflectivity distribution profile of a fiber Bragg grating, the oscillation wavelength λ_l of fiber Bragg grating semiconductor lasers has been investigated theoretically. The results show that the laser oscillation wavelength λ_B is not fixed at the Bragg reflection wavelength λ_l of fiber Bragg grating, and the offset between λ_B and λ_l depends on the reflectivity distribution profile of fiber Bragg grating and the gain profile of semiconductor gain medium.     

Switchable single-longitudinal-mode dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating incorporating saturable absorber and feedback fiber loop

Switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating (PMFBG) is demonstrated. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The stable SLM operation is guaranteed by a compound-ring cavity and a saturable absorber (SA). The optical signal-to-noise ratio (OSNR) is over 45 dB. The amplitude variation in nearly one and half an hour is less than 0.2 dB.     

Switchable triple-wavelength erbium-doped fiber laser using a single fiber Bragg grating in polarization-maintaining fiber

A stable and narrow wavelength spacing multiwavelength erbium-doped fiber laser is proposed and demonstrated. The laser can produce simultaneous dual- and triple-wavelength lasing oscillations with a narrow wavelength spacing of less than 0.1 nm via using a single fiber Bragg gratings written in polarization-maintaining (PM) fiber. By adjusting polarization controller, the wavelength spacing of dual-wavelength lasing oscillations can be tuned to as small as 0.032 nm. The maximum amplitude variation for every lasing wavelength is less than 0.5 dB. The room-temperature operation principle is based on the polarization hole burning and deeply saturated effect in an ordinary erbium-doped fiber ring laser (EDFRL). The laser has the advantages of simple all-fiber configuration, low cost, high stability and operating at room temperature.     

中心波长1080 nm的高功率光纤光栅研制与测试

介绍了基于紫外光侧写和相位掩模法制作双包层光纤光栅的工艺,制作了一对中心波长1080 nm的光纤光栅,测试光谱得到其反射谱带宽分别为2 nm和1 nm。采用自制的光纤光栅搭建了一个高功率光纤振荡器,得到最高502 W的激光输出,并测试了输出激光的光谱和光束质量。     

基于体光栅的被动锁模可调谐线型腔掺镱光纤激光器

搭建了基于反射型体光栅和半导体可饱和吸收镜的线型腔全正色散掺镱光纤激光器,室温下实现了稳定的波长可连续调谐的连续被动锁模脉冲输出.重复频率16.42 MHz,锁模脉冲中心波长1030 nm时,脉冲光潜带宽0.32 nm,最大平均输出功率10.2 mW,单脉冲能量0.63 nJ.转动体光栅角度,利用其分光谱和选波长的特性,可使锁模脉冲的中心波长在约1011.9一1050.6 nm的范围内调谐,调谐范围约38.7 nm.实验中亦可观察到调Q锁模、二次谐波锁模、双波长和三波长输出现象.输出单波长锁模脉冲时,由于其波长可调谐的特性,该激光器可用作波分复用/光时分复用通信系统的光源和光学相干层析的调谐光源.     

Radio-frequency interrogation of a fiber Bragg grating sensor in the configuration of a fiber laser with external cavities

A fiber laser sensor, which consists of two coupled cavities based on three fiber Bragg gratings (two of them acting as sensing elements) and is interrogated via the longitudinal mode beating frequency, is presented. The two resonant cavities have lengths of 4250 m and 4297 m, respectively. Their beating frequency is of the order of 24 kHz, and its shift as a function of the variation of the period of one (or both) of the sensing gratings, induced by strain or temperature changes, can be measured by a radio-frequency analyzer. The system is suitable for long-distance sensing with high spatial resolution and high sensitivity.     

Wideband tunable linear-cavity fiber laser source using strain-induced chirped fiber Bragg grating

A novel wideband tunable linear-cavity fiber laser source using strain-induced chirped fiber Bragg grating (FBG) and erbium–ytterbium co-doped fibers is proposed and demonstrated for the first time. The strain-induced chirped FBG, which acts as a partial-reflecting mirror, is achieved by bending a uniform FBG bonded at a slant onto the lateral surface of a simply supported beam. A single wavelength lasing with a maximum wavelength tuning range of 17 nm has been achieved experimentally.     

Tunable multi-wavelength combined linear-cavity fiber laser source with equally changed wavelength spacing

A tunable multi-wavelength combined linear-cavity fiber laser source with equally changed wavelength spacing is proposed for the first time. The wavelength tuning is realized by stretching or compressing the fiber Bragg gratings incorporated in the laser cavity. To ensure a wavelength tuning with equally increased or decreased wavelength spacing, the gratings are mounted onto a plastic plate with angles between adjacent gratings such that the forces applied to the gratings has an equal force increment. A four-wavelength lasing with equal increased or decreased wavelength spacing is achieved experimentally.     

基于偏振保持掺Er3+光纤的高稳定性单波长光纤激光器

研制出光敏偏振保持掺Er³⁺光纤,通过在这种光纤上紫外写入三个光纤光栅,形成对抽运激光高转化效率的谐振腔.在输出功率为23.617dBm、工作波长为976nm的激光抽运下,得到均值功率为9.20dBm、均值中心波长为1554.554nm的单波长激光输出.在室温下800min（约13.3h）的测量时间内,其输出功率的波动为±0.05dB,中心工作波长的波动为±0.0015nm. 关键词： 光纤激光器 3+光纤')" href="#">偏振保持掺Er³⁺光纤 光纤Bragg光栅     

Erbium-doped fiber ring laser sensor for high temperature measurements based on a regenerated fiber Bragg grating

This article presents an erbium-doped fiber ring laser for high temperature measurement with high accuracy. The proposed laser sensor employs a regenerated fiber Bragg grating (RFBG) as a sensor element. Through thermal treatments, the RFBG with enhanced thermal resistance was obtained. The laser emission optical spectrum presents good performance with a high optical signal-to-noise ratio of 58dB. Experimental results demonstrate a wavelength sensitivity to the temperature is 15.5 pm/ºC with the temperature range from 300ºC to 900ºC, and the correlation coefficient is 0.999. The results prove it is able to provide potential applications in high temperature measurement.     

基于飞秒激光直写光纤光栅的掺镱光纤激光器

 利用飞秒激光微加工技术,可以在光纤纤芯内直写出布拉格光栅,它与传统的光纤光栅制作方法相比,具有耗时短、无需光敏光纤、周期可任意设定、光栅稳定性高等优点。采用800 nm钛宝石飞秒激光器,在Hi1060光纤内写入一支8 mm长的布拉格光栅,光纤光栅的周期为2.9 μm,这是中心波长为1 042 nm的八阶光纤布拉格光栅。将所得光栅与一段有源的双包层光纤熔接,作为激光输出镜,利用975 nm的LD光纤模块作为泵浦源,采用端泵浦技术构成双包层光纤激光器。双包层光纤采用Nufern公司镱(Yb³⁺)离子掺杂双包层光纤,光纤长度3 m。所得激光器的输出功率为71.1 W,中心波长1 042 nm,带宽约为0.8 nm。     

双光纤光栅外腔半导体激光器相干失效研究

根据双光纤Bragg光栅(FBG)外腔半导体激光器相干失效的物理过程, 运用速率方程和双FBG耦合模理论, 分析了双FBG外腔半导体激光器相干失效产生和控制的条件, 提出了实现和控制双FBG外腔半导体激光器相干失效多模稳定工作的方法. 双FBG外腔半导体激光器在相干失效下具有多模的稳定工作状态, 相干失效长度缩短, 相干失效长度内光谱稳定. 实验测量结果表明, 外腔反射率为3%时, 从非相干失效状态到相干失效状态, 半峰值全宽度从0.5 nm突然展宽到0.9 nm. 在相干失效状态下, 功率稳定, 边模抑制比大于45 dB, 在0℃–70℃工作温度范围内峰值波长漂移小于0.5 nm, 最小相干失效长度小于0.5 m. 双FBG外腔半导体激光器相干失效的应用对提高光纤放大器和光纤激光器的性能具有重要意义. 关键词： 非线性 半导体激光器 双光纤Bragg光栅 相干失效     

High frequency microwave signal generation using dual-wavelength emission of cascaded DFB fiber lasers with wavelength spacing tunability

A dual-wavelength fiber laser source based on two cascaded phase-shifted fiber Bragg gratings is presented. The gratings are written in an erbium-doped fiber, each configuring the cavity of a distributed feedback fiber laser. The spacing between lasing modes is controlled dynamically by the use of piezoelectric actuators. A continuous tuning range of 5-724 pm of the wavelength difference, which is equivalent to a photodetected 0.72-92 GHz range, is obtained. Efficient generation from the L to the W microwave and millimeter bands has been achieved by heterodyne photodetection of the dual-wavelength optical signal.     

基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术

首次提出了一种基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术, 利用保偏光纤光栅选频产生两个偏振稳定的激光信号, 采用扰偏器确保激光输出的两个正交偏振态功率的一致性, 最后输入高速光电探测器产生微波/毫米波. 通过对保偏光纤光栅施加不同大小的侧向应力, 可以灵活调谐输出的毫米波频率. 实验制作了基于偏振稳定双波长保偏光纤光栅激光器的可调 谐微波/毫米波产生装置, 通过对保偏光纤光栅施加不同的轴向拉力分别产生了20.407 和22.050 GHz的微波信号. 仿真产生了60 GHz的毫米波信号, 并分析该毫米波在光纤无线通信下行链路的传输性能, 结果表明该毫米波作为副载波调制到光波上从中心站传输80 km至基站后经天线发射至用户端, 解调后仍然得到很好的眼图, 充分证明了本方案的优越传输性能.     

分布式反馈激光器动态扫描光纤布拉格光栅波长解调系统

通过对该系统采集到的法布里-珀罗(F-P)标准具透射谱和光纤布拉格光栅(FBG)传感器反射谱进行寻峰算法以及拟合算法的研究,采用C语言编程和LabVIEW编程相结合的方式,实现了FBG波长信号的解调。其中,由于系统采集到的F-P透射谱和FBG反射谱线时域信号数据都由离散点构成, 且在3 dB带宽内均符合高斯曲线分布,采用高斯拟合对采集到的信号数据进行寻峰处理,提高系统精度;又由于分布式反馈(DFB)激光器的波长扫描存在着一定的非线性,采用二项式拟合对DFB激光器的波长扫描曲线进行拟合,以降低其非线性导致的误差。另外,设置一路标准FBG传感通道用于波长校准。实验研究表明该系统稳定性良好,波长测量范围为1 550.012~1 554.812 nm,分辨力为1 pm,精度为10 pm,验证了该系统可用于FBG波长信号检测的可行性。     

基于线型腔掺铒光纤激光器的光纤光栅传感实验研究

提出了一种基于线型腔掺铒光纤激光器的光纤布拉格光栅传感解调系统,并进行了理论分析和实验验证。此传感系统具有稳定性好、信噪比高、结构简单等特点。实验结果表明:在常温下光纤光栅传感解调系统能很好的实现光纤光栅传感信号的传感和检测;15m掺铒光纤用作增益介质可以产生较大信噪比的稳定激光输出,系统在4nm范围内的解调精度为0.04nm。     

高斯切趾型光纤布拉格光栅外腔半导体激光器的混沌输出特性

基于光反馈半导体激光器(SL)速率方程模型,理论仿真研究了高斯切趾型光纤布拉格光栅(GAFBG)反馈SL(GAFBGF-SL)混沌输出的延时特征(TDS)以及混沌带宽特性.结果表明:随着反馈强度的增加,GAFBGF-SL表现出由准周期进入混沌的动力学演化路径;通过合理选择GAFBG布拉格频率与SL中心频率之间的频率失谐及反馈强度,GAFBGF-SL混沌输出的TDS能得到有效抑制(低于0.02);通过进一步绘制混沌信号TDS及带宽在GAFBG布拉格频率与SL中心频率之间的频率失谐和反馈强度构成的参量空间中的分布图,确定了获取弱TDS、宽带宽光混沌信号的参数范围.