Double spacing multi-wavelength L-band Brillouin erbium fiber laser with Raman pump

A new multi-wavelength Brillouin erbium fiber laser (BEFL), which operates in the L-band region with double frequency Brillouin spacing, is demonstrated. This design uses a Raman pump (RP) and a piece of 2?km highly nonlinear fiber as a gain medium. The double frequency spacing is achieved by employing a dual ring configuration, which is formed by utilizing a four-port circulator that removes the odd-order Stoke signals. Twenty Stokes and seventeen anti-Stokes lines, which have optical signal to noise ratio (OSNR) greater than 15?dB, are generated simultaneously with a spacing of 0.16?nm when Brillouin pump and RP powers were fixed at the optimum values of 8 dBm and 40?mW, respectively. The BEFL can be tuned in the range between 1591?nm to 1618?nm. The proposed configuration increases the number of lines generated and the OSNR, and thus allows a compact multi-wavelength laser source to be realized.     

Stability function of lightwaves based on the cascade of multiple four-wave mixing processes and its application to multi-wavelength erbium lasers

On the basis of the cascade of multiple four-wave mixing (FWM) processes, the energy stability function of multiple lightwaves propagating through fibers is proved theoretically and confirmed experimentally. This function can help multiple lasers to redistribute power from those that have more to those that have less. Theoretical and experimental results show that the ability of the FWM-induced stability effect gradually becomes weaker with the increase of pump number. The stability effect of waves by multiple FWM processes can effectively overcome the homogeneous gain broadening of an erbium-doped fiber (EDF). By adjusting the attenuators and tuning fiber Bragg gratings, dual-, triple-, and four-wavelength EDF lasers with good stability are demonstrated experimentally at room temperature.     

Semiconductor optical amplifier-based multi-wavelength ring laser utilizing photonic crystal fiber

A multi-wavelength laser source is demonstrated with a semiconductor optical amplifier (SOA) as a gain medium. A multi-wavelength comb with equal spacing is achieved due to Fabry–Pérot modes of the SOA which oscillates in the ring cavity. A 100 m long photonics crystal fiber (PCF) is inserted in the ring cavity to provide a nonlinear gain by four-wave mixing (FWM) so that the output comb spectrum can be greatly broadened and flattened. The stability of the ring laser is also increased due to the efficient FWM phenomenon occurring in the PCF. The SOA-based laser can generate 35 lasing lines with equal spacing of 0.28 nm and extinction ratios of more than 30 dB at room temperature. The number of channels of the multi-wavelength laser can be controlled flexibly by changing the ratio of the coupler used in the ring cavity configuration as well as controlling the polarization state of the oscillating laser.     

Passively Q-switched multi-wavelength Nd:YVO4 self-Raman laser

Abstract

Multi-wavelength self-Raman laser from a passively Q-switched c-cut Nd: YVO₄ laser at 1066.8 nm to four discrete Stokes lines at 1097.2, 1129.2, 1168.3 and 1178.8 nm is demonstrated simultaneously for the first time. With a 0.27 at% c-cut Nd:YVO₄ crystal, the total output power of Stokes lines is 267 mW at a pump power of 5.0 W.     

Investigation of the effects of SOA locations in the linear cavity of an O-band Brillouin SOA fiber laser

An investigation into the effect of semiconductor optical amplifier (SOA) location in an O-band Brillouin SOA fiber laser (BSFL) was performed. Better output peak power flatness was generated by placing the SOA after the nonlinear medium, which is a 20?km true wave fiber (TWF) than placing it before the TWF. A maximum power of six flat output peaks with average power of ?22.0?dBm for a BP (Brillouin pump) wavelength of 1320?nm was obtained, generated from a BSFL with a SOA located after the TWF, compared with three flat Stokes signals with the SOA before the TWF at a BP wavelength of 1310?nm. The flat peak power output for the O-band Brillouin fiber laser is important, especially in producing a good O-band source.     

多波长法金属防热瓦表面温度及发射率的测量

为了解决金属防热瓦在连续加热过程中热边温度和发射率的测量问题,在基于辐射测温的参考温度数学模型的连续测量法中采用了一种新的发射率假设模型,并在此基础上提出了多波长数据处理方法.该方法假设材料的光谱发射率在选定的光谱处与温度有近似相同的线性关系,通过处理两个不同温度点处的多光谱测量数据以得到防热瓦真温及光谱发射率.使用多波长高速高温计测量了某种防热瓦在900～1300℃的温度范围内的辐射,并进行了数据处理.实验结果表明,只要温度估计初值与真实情况的误差在±200℃以内,即可得到较好的计算温度值和计算发射率值,测量不确定度在2%以内,说明此方法是测量金属防热瓦表面温度及发射率的可行方法.     

多纤多波长光网络的动态路由等效算法

针对多光纤多波长光网络的特点,提出了一种动态路由和波长分配的等效算法。采用波长图、增加虚拟源节点和目的节点、引入光纤数量矩阵等技术,把多纤多波长网络转化为等效的单波长网络,大大简化了算法程序的复杂度。采用最短径算法作为算法的基础,可求得每次业务在全网范围内的路由和波长分配的最优解。仿真结果表明,当网络呼叫量为60时,全波长转换情况下,2纤、4纤网络的阻塞率分别为0.1116、4.3×10-5。     

光波导位相调制技术产生多波长光源

用Matlab软件模拟分析了高频光波导电光位相调制器的输出光谱特性。结果表明,在一定频率的微波源作用下,单色光通过光波导位相调制器后会产生光频谱展宽,展宽光谱中包括中心波长及各阶光边波带。随位相调制深度加大,边波带数目增多,光谱展宽增大;位相调制深度为3.3时,10dB展宽光谱中含边波带数为8个。实验制作了光波长1．55μm、微波频率10GHz的铌酸锂电光波导位相调制器;输出光谱中可清楚观察到正负三阶等频率间隔的边波带,即可实现七路光源输出,由此提出并验证了光波导位相调制技术用作多波长光源的可能性。利用位相调制器的光频谱展开得到多波长光源,具有成本低．易实现、促进系统集成等优点,有良好的应用前景。     

Ultra-High bit rate all-optical AND/OR logic gates based on photonic crystal with multi-wavelength simultaneous operation

In this paper, a novel two-dimensional photonic crystal based all-optical AND/OR logic gates are designed, simulated and optimized. The structure is built on a linear square lattice photonic crystal platform. A multi-wavelength operation, together with a simultaneous operation, is achieved at ultra-high bit rates. The concurrent operation is attained without altering the proposed design continuously, as stated in the literature. It provides simplicity because there is no auxiliary input required along with the absence of externally attached phase shift units. The enhancement process has been done to the rod radius. A magnificent representation tool is developed. The benefit of the mentioned tool lies in the data combination of different operating wavelengths, contrast ratio, and bit rate; which will establish an efficient optimization process. Each gate is enhanced independently, then an overall improvement has been done. As a result, the operation at 1.52?µm will provide a successful multi logic gate operation with ultra-high bit rates of 6.76 and 4.74 Tbit/s for AND and OR logic gates, respectively. The design has an acceptable size of (19.8?×?12.6 µm) and a contrast ratio of 9.74?dB and 17.95?dB for the designed AND and OR gate, respectively. The design is highly sensitive to the waveguide length to verify the gates on demand.     

Frequency switching multiwavelength Brillouin Raman fibre laser based on feedback power adjustment technique

A simple switchable multiwavelength Brillouin–Raman fibre laser (BRFL) was demonstrated. The laser was arranged in a half-open cavity configuration including a physical mirror device with an adjustable reflectivity at one side of the laser cavity. The impact of the feedback power adjustment on frequency switching was carried out by comparing the peak power difference between odd- and even-order Stokes lines. Up to 468 flat-amplitude lines with a 10?GHz frequency spacing and average optical signal to noise ratio (OSNR) of 33 dB were observed with mirror reflectivity values of ～15% up to 60% at a 1534?nm Brillouin pump power of 7?dBm and 0.9?W Raman pump power of 0.9?W. – Under the same pumping conditions, setting the mirror reflectivity at its OFF state (where reflectivity is nearly 0%) allows for up to 242 lines with 20?GHz spacing to be realized, with ONSR values of ～35?dB.     

Laser wavelength tunability of a diode-pumped Nd:LiYF4 laser on the 4F3/2–4I13/2 transition

Abstract

We report a free-running orthogonally polarized dual-wavelength laser at 1313 and 1321 nm with maximum total output power of about 1.73 W using a two-mirror linear cavity. By inserting an etalon into the linear cavity, single-wavelength lasers at 1317 or 1323 nm, two-wavelength lasers at 1317 and 1323 nm, as well as four-wavelength lasers at 1313, 1317, 1323 and 1370 nm can be achieved with maximum output powers of about 0.73, 0.63, 0.78 and 0.25 W, respectively. About 10-nm wavelength tunability from about 1313 to 1323 nm is also realized by inserting the etalon into a three-mirror V-type Nd:YLF laser cavity.     

L-Band multi-wavelength erbium-doped fibre laser based on non-linear optical loop mirror and dual-channel Mach–Zehnder interferometer

In this letter, we propose and demonstrate an L-Band linear cavity tunable multi-wavelength erbium-doped fibre laser based on non-linear optical loop mirror (NOLM) and dual-channel Mach–Zehnder interferometer (MZI) . The NOLM provides the intensity-dependent transmissivity, can effectively alleviate the mode competition and beating caused by the homogeneous gain broadening, so that the multi-wavelength lasing can be achieved at room temperature. The dual-channel MZI, configured by linking the two outputs of the single-channel MZI, serves as comb filter. By adjusting the polarization controller in NOLM and pump power, the tunable multi-wavelength output at 1600 nm can be achieved. Moreover, the output stability of the laser has also been accomplished .     

Dual wavelength fibre laser with tunable channel spacing using an SOA and dual AWGs

In this paper, we propose and demonstrate a dual wavelength fibre laser (DWFL) based on the use of an inhomogeneously-broadened semiconductor optical amplifier (SOA) gain medium as well as two arrayed waveguide gratings (AWGs) together with two optical channel selectors (OCSs) and a broadband fibre Bragg grating (FBG) to generate dual wavelength output at variable channel spacings. The widest spacing obtained from the DWFL is 12.21 nm, while the narrowest spacing is 1.16 nm. The DWFL has good stability with only minor power fluctuations of less than 2 dB and a side mode suppression ratio (SMSR) of approximately 38.5 dB with fluctuations of less than 0.5 dB.     

Tunable S-band output based on Raman shift in dispersion shifted fiber

A tunable short-wavelength band Raman fiber laser using a dispersion shifted fiber as the nonlinear medium is proposed and demonstrated. This approach provides an alternative to the common method of using depressed-cladding, erbium-doped fibers as the gain medium in S-band fiber lasers. The proposed laser has a tuning range of 1508 to 1534?nm as well as an average peak power of about ?11.3?dBm within the range 1518–1530?nm. A high signal-to-noise ratio of approximately 70 dB is obtained from the system at this range.     

Tunable single longitudinal mode S-band fiber laser using a 3 m length of erbium-doped fiber

In this paper a tunable single-longitudinal mode (SLM), short-wavelength band (S-band) fiber laser using a conventional erbium-doped fiber (EDF) with a length of 3?m and a step index erbium dopant profile as opposed to the commonly used depressed cladding erbium-doped fiber (DC-EDF) is proposed and demonstrated. The proposed SLM fiber laser has a tuning range of 1496 to 1507?nm in a ring configuration using two 0.15?m of EDF which acts as saturable absorbers (SAs). The highest peak power measured is about ?0.6?dBm at a wavelength range of 1502 to 1507?nm. The measured signal-to-noise ratio (SNR) is approximately 74?dB for the same wavelength range. The line-width of the SLM output is measured to be 140?kHz.     

Multi-wavelength Q-switched Erbium-doped fiber laser with photonic crystal fiber and multi-walled carbon nanotubes

A simple multi-wavelength passively Q-switched Erbium-doped fiber laser (EDFL) is demonstrated using low-cost multi-walled carbon nanotubes (MWCNTs)-based saturable absorber, which is prepared using polyvinyl alcohol as a host polymer. The multi-wavelength operation is achieved based on non-linear polarization rotation effect by incorporating 50?m long photonic crystal fiber in the ring cavity. The EDFL produces a stable multi-wavelength comb spectrum for more than 14 lines with a fixed spacing of 0.48?nm. The laser also demonstrates a stable pulse train with the repetition rate increasing from 14.9 to 25.4?kHz as the pump power increases from the threshold power of 69.0?mW to the maximum pump power of 133.8?mW. The minimum pulse width of 4.4?μs was obtained at the maximum pump power of 133.8?mW while the highest energy of 0.74 nJ was obtained at the pump power of 69.0?mW.     

Self-seeded multi-wavelength Brillouin–erbium fibre laser with 20 GHz frequency gap

We demonstrate a self-seeded multi-wavelength Brillouin–erbium fibre laser with double Brillouin frequency gap. The twice channel gap is induced by the gain difference in different directions. Thirty-six stable output channels with 20?GHz frequency gap are obtained when the 980?nm pump power is 300?mW. The factor that induces the double frequency gap is investigated and proved.     

高功率宽带掺铒超荧光光源

采用单程后向结构,通过优化掺铒光纤的长度及抽运功率等参量,并尽量提高熔接效率,实现了一种功率达28.58mW(14.56dBm)的高功率宽带光源,在1525-1565nm之间功率高达27.34mW(14.37dBm)。在未加任何滤波器的情况下,其3dB带宽为31.2nm。对一根光纤中前向与后向光光谱特点进行分析比较。结果表明,用一段光纤和一只二极管可实现C L波段的宽带高功率光源,结构紧凑,成本低。     

光纤饱和吸收体稳频窄线宽光纤激光器

结合光纤饱和吸收体与光纤光栅法布里-珀罗标准具,研制出了全光纤结构1550nm单频窄线宽掺铒光纤环形激光器.采用两个976nm激光二极管双向抽运作为抽运源,高掺杂浓度铒光纤作为增益介质,以行波腔消除空间烧孔效应,利用光纤光栅法布里-珀罗标准具窄带选模特性,以10m长低掺铒光纤饱和吸收体稳频,得到了十分稳定的窄线宽激光输出.激光器抽运阈值功率21mW,在抽运光功率为145mW时输出光功率39mW,斜率效率30%,信噪比大于50dB.采用延迟自外差方法精确测量光纤激光器线宽小于10kHz.     

光纤微流传感技术研究进展

本文介绍了本课题组在光纤微流激光传感器和无源光纤微流传感器两方面的研究进展。光纤微流激光传感器利用光纤微流激光的输出变化来探测生化参数的改变。光纤截面作为环形微腔形成光反馈,增强了腔内光子和待测物质的相互作用,从而提高了微流激光的传感灵敏度。此外,光纤尺寸均匀,易低成本、批量制作光纤微腔,可制备高重复性或一次性使用的光纤微流激光。本文还介绍了基于光力/光热效应的无源光纤微流传感器。该类传感器利用光产生的力学或热学效应对微流体进行温度、流速、浓度传感,具有灵活性高、集成度好、多功能、可重构等特点。