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.     

用半导体激光器作调制器的双波长可调谐锁模光纤激光器

提出一种用法布里—珀罗腔半导体激光器(F—PLD)作调制器，用线性凋啾光栅(LCFG)进行波长选择的双波长环形腔主动锁模光纤激光器。利用线性凋啾光栅在腔内的色散效应使两个波长的光脉冲通过饵光纤(EDF)时在时域上分开，从而威小了不同波长的光脉冲同时通过饵光纤时造成的竞争，因此可以在室温下获得波长间隔较小的稳定的双波长光脉冲输出。实验中成功地获得了重复频率约为2GHz，波长间隔为0．92nm的稳定双波长光脉冲，并通过调谐线性凋啾光栅中心波长的位置使激光波长可以在约3nm范围内调谐。     

Switchable dual-wavelength polarization-maintaining erbium-doped fiber laser using an optical circulator as the all-reflecting mirror

A simple and effective switchable dual-wavelength polarization-maintaining erbium-doped fiber laser is proposed and demonstrated. Only using a uniform fiber Bragg grating written directly in a segment of the photosensitive and polarization-maintaining erbium-doped fiber as the wavelength selector and an optical circulator as the all-reflecting mirror, a stable simultaneous dual-wavelength oscillation is achieved with a wavelength spacing of 0.364 nm experimentally by exploiting the polarization hole burning effect at room temperature. The output can be switched between single- and dual-wavelength by adjusting the polarization controller. The 3-dB bandwidth and the side mode suppression ratio of the laser’s outputs are measured to be less than 0.01 nm and more than 50 dB. The power fluctuation and wavelength drift are measured to be less than 0.50 dB and 0.020 nm over an hour.     

Incorporate, switchable dual-wavelength fiber laser with Bragg gratings written in a polarization-maintaining erbium-doped fiber

A stable, incorporate and switchable dual-wavelength fiber laser with two fiber Bragg gratings written in a photosensitive and polarization-maintaining erbium-doped fiber directly, that is, without splices in the laser cavity, is proposed and demonstrated. Simultaneous dual-wavelength oscillation is achieved at room temperature with a wavelength spacing of 0.343 nm. The power fluctuation and wavelength shift of single-wavelength oscillations are measured to be less than 0.24 dB and 0.013 nm over 2 h. The wavelength switchability between single- and dual-wavelength oscillations is realized by altering the voltage upon the electrostrictive ceramic actuator.     

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.     

A stable dual-wavelength fiber laser with tunable wavelength spacing using a polarization-maintaining linear cavity

We propose and experimentally demonstrate a stable dual-wavelength erbium-doped polarization-maintaining (PM) fiber laser with tunable wavelength spacing using an all-PM linear cavity that makes use of two reflection peaks from the PM fiber Bragg grating (PM-FBG). Experimental results show stable dual lasing lines with a wavelength separation of ∼0.22 nm and a large optical signal-to-noise ratio (OSNR) of over 40 dB under room temperature. By applying axial strain to the PM-FBG, the center wavelengths of the two lasing lines can be tuned over several nanometers and the wavelength separation between the lasing lines can also be tuned to as small as 0.05 nm, which, to our knowledge, is the smallest wavelength spacing ever obtained from a stable room-temperature dual-wavelength fiber laser. The proposed laser configuration has the advantages of simple structure, low loss, stable dual-wavelength operation and a very small lasing linewidth of ∼5 kHz . PACS 42.55.Wd; 42.81.-i; 42.81.Gs     

Synchronous tunable wavelength spacing dual-wavelength SOA fiber ring laser using Fiber Bragg grating pair in a hybrid tuning package

A Dual-Wavelength Semiconductor Optical Amplifier (DW-SOA) based fiber ring laser with synchronous wavelength tunability is proposed and experimentally demonstrated. The SOA gain medium strongly suppresses mode competition, thus allowing stable dual-wavelength laser oscillation. The wavelength spacing of the two lasers can be tuned synchronously using a modified hybrid-tuning package incorporating a pair of Fiber Bragg Gratings (FBGs). The DW-SOA demonstrates a laser output with a wavelength spacing of between 0.10 and 8.30 nm (wavelength shift inequality of 0.08 to 0.75 nm). The relationship between the applied strain and wavelength shift of the two tuning modes is also analyzed.     

Wavelength spacing tunable dual-wavelength single-longitudinal-mode fiber ring laser based on fiber Bragg gratings

A wavelength spacing tunable dual-wavelength single-longitudinal-mode fiber ring laser is presented by employing separated fiber Bragg gratings. By using a saturable-absorption-induced grating filter and a hybrid gain medium formed by a semiconductor optical amplifier and an erbium-doped fiber amplifier, stable single-longitudinal-mode lasing is achieved at room temperature. Wavelength spacing of the proposed fiber laser can be tuned in a range from 0.1 to 1.3 nm.     

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.     

Switchable single- and dual-wavelength erbium-doped fiber laser assisted by four-wave mixing with wide and continuous tunability

A widely tunable and stable erbium-doped fiber laser based on four-wave mixing effect in a highly nonlinear fiber is proposed and experimentally demonstrated. By adjusting reflected power from a dual-selective element, the ring laser is switchable between single- and dual-wavelength operations. The tuning range of the single laser is 22.78 nm, from 1,542.07 to 1,564.85 nm, while the wavelength spacing of the dual-wavelength can be continuously tuned from 0.52 to 22.78 nm. The laser is stable with output peak power fluctuation of <1 dB in 30-min interval.     

Dual wavelength erbium-doped fiber laser with a lateral pressure-tuned Hi-Bi fiber Bragg grating

Tunable dual wavelength erbium-doped fiber laser (EDFL) with stable oscillation at room temperature is proposed and demonstrated. This laser utilizes a Bragg grating fabricated in a high birefringence fiber as the wavelength-selective component, and then achieves the stable dual wavelength oscillation by introducing the polarization hole burning effect. Furthermore, by applying lateral strain upon the fiber Bragg grating (FBG), the space of the laser dual wavelengths can be tuned continuously.     

A tunable narrow-line-width multi-wavelength Er-doped fiber laser based on a high birefringence fiber ring mirror and an auto-tracking filter

A novel multi-wavelength erbium-doped fiber laser operating in C-band is proposed and successfully demonstrated. The wavelength interval between the wavelengths is about 0.22 nm. The 3 dB bandwidth of the laser is about 0.012 nm, and the output power reaches 4.8 mW. By using a high birefringence fiber ring mirror (HiBi-FLM) and a tunable FBG, the laser realizes switchable and tunable characteristic. The mode hopping can be effectively prevented. Moreover, this laser can improve wavelength stability significantly by taking advantage of an un-pumped Er³⁺-doped fiber at the standing-wave section. The laser can operate in stable narrow-line-width with single-, dual-wavelength, and unstable triple-wavelength output at room temperature.     

Dual-wavelength Brillouin ring-cavity fiber laser with tunable channel spacing

We experimentally demonstrate a dual-wavelength Brillouin fiber laser configured a pre-amplified Brillouin pump and FBG filter in a ring-cavity. The Brillouin laser can generate 21 Brillouin Stokes with 0.084 nm spacing, the first-Stoke has a peak power of 2.19 dBm. By adjusting the TLS wavelength and FBG’s reflection wavelength from circulating in the ring-cavity, the generated output dual-wavelength is stabile and the channel spacing is tunable, the widest and narrowest channel spacing obtained is approximately 1.12 nm (139 GHz) and 0.084 nm (10.5 GHz).     

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.     

波长间隔可调的可开关双波长掺铒光纤激光器

对两种波长间隔可调的可开关双波长掺铒光纤激光器结构进行了实验研究。一种结构应用保偏光纤中布拉格光栅作为波长选择器件，另一种结构则利用侧向压力下的常规单模光纤光栅作为波长选择器件。两种结构均利用了光纤光栅的双折射特性。在室温下，通过调整偏振控制器的状态可使两激光器工作在稳定的双波长状态或在两单波长之间转换。通过改变加在光纤光栅上侧向应力的大小和方向，可有效控制双波长激射的波长间隔。     

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.     

Tunable microwave signal generation based on an Opto-DMD processor and a photonic crystal fiber

Frequency-tunable microwave signal generation is proposed and experimentally demonstrated with a dual-wavelength single-longitudinal-mode （SLM） erbium-doped fiber ring laser based on a digital Opto-DMD processor and four-wave mixing （FWM） in a high-nonlinear photonic crystal fiber （PCF）. The high-nonlinear PCF is employed for the generation of the FWM to obtain stable and uniform dual-wavelength oscillation. Two different short passive sub-ring cavities in the main ring cavity serve as mode filters to make SLM lasing. The two lasing wavelengths are electronically selected by loading different gratings on the Opto-DMD processor controlled with a computer. The wavelength spacing can be smartly adjusted from 0.165 nm to 1.08 nm within a tuning accuracy of 0.055 nm. Two microwave signals at 17.23 GHz and 27.47 GHz are achieved. The stability of the microwave signal is discussed. The system has the ability to generate a 137.36-GHz photonic millimeter signal at room temperature.     

Tunable dual-wavelength fiber laser based on an opto-VLSI processor and four-wave mixing in a photonic crystal fiber

A stable wavelength and wavelength spacing tunable dual-wavelength fiber laser based on an Opto-very-large-scale-integration (Opto-VLSI) processor and four-wave mixing (FWM) in a high-nonlinear photonic crystal fiber is experimentally demonstrated. The results show that the line width of the tunable dual-wavelength fiber laser is 0.02 nm, and the wavelength spacing can be tuned from 0.8 nm to 4 nm with a 0.15 nm step. Under the influence of the FWM, the uniformity is below 0.6 dB and the measured side mode suppression ratio (SMSR) is above 45 dB.     

Stable dual-wavelength erbium-doped fiber laser using novel fabricated side-polished arc-shaped fiber with deposited ZnO nanoparticles

A dual-wavelength fiber laser operating at the 1550 nm region using a side-polished arc-shaped fiber with deposited ZnO nanoparticles is proposed and demonstrated. The arc-polished fiber is fabricated by using a simple but novel approach in which a silicon carbide paper polishes one side of a conventional single-mode fiber. An arc-polished fiber with a length of 2.25 mm and an insertion loss of 0.95 dB is obtained and deposited with ZnO nanoparticles by the drop-cast method. A stable dual-wavelength output is obtained at 1562.5 and 1563.4 nm at peak powers of-9.3 and-10.1 dBm, respectively, as well as a signal-to-noise ratio of 28.4 dB and a channel spacing of 0.9 nm. Both lasing wavelengths also have narrow linewidths of between 0.045 and 0.049 nm and show little to no wavelength or power fluctuations over continued testing.     

基于相位采样光栅的双波长光纤激光器

提出一种基于相位采样的分布反馈式双波长光纤激光器,在不同的空间化置同时引入相位和采样周期的突变.通过理论分析,这种结构能够实现谐振腔的分离,使不同波长的光波利用不同空间位置的增益介质,克服增益介质均匀加宽引起的模式竞争,实现双波长激射.采用准分子激光器和均匀相位模板,在掺铒光纤上制作波长差为0.46 nm的舣波长光纤激光器,能够实现舣波长激射.通过实验,对激光器输出功率和光栅强度的关系进行研究,表明输出功率和光栅强度成反比.