Lasing wavelength and spacing switchable multiwavelength fiber laser from 1510 to 1620 nm

We experimentally demonstrate a flexibly switchable multiwavelength fiber laser with multiple functionalities like a wide tuning range of lasing wavelength, wavelength spacing, and the number of channels simultaneously. The lasing wavelength is controlled in the range from 1510 to 1620 nm based on the effect of nonlinear gain compression of a semiconductor optical amplifier incorporated with an erbium-doped fiber amplifier. The wavelength spacing and the number of channels in the multiwavelength fiber laser are readily controlled by the effective length of polarization-maintaining fiber (PMF) segments in the intracavity PMF Lyot-Sagnac filter.     

Tunable multiwavelength fiber ring lasers using a programmable high-birefringence fiber loop mirror

We demonstrate a comb filter with digitally tunable wavelength spacing using a programmable high-birefringence (HiBi) fiber loop mirror (FLM). We then use the HiBi-FLM to implement a tunable multiwavelength semiconductor optical amplifier (SOA)-based fiber ring laser and a tunable multiwavelength all-fiber Raman ring laser. Both lasers exhibit stable room-temperature operation and have a wavelength spacing that is digitally tunable between 1.6 and 3.2 nm. With the SOA-based configuration, we obtain six wavelengths with a spacing of 3.2 nm and 11 wavelengths with a spacing of 1.6 nm; with the all-fiber Raman-based configuration, we obtain four wavelengths with a spacing of 3.2 nm and five wavelengths with a spacing of 1.6 nm.     

Dual-Wavelength DFB Fiber Laser Based on a Chirped Structure and the Equivalent Phase Shift Method

A chirped phase-shifted structure is demonstrated for compact multiwavelength distributed feedback (DFB) fiber laser at room temperature for the first time. The chirped structure provides separated resonance cavities and then the stable multiwavelength operation. The equivalent phase shift method is demonstrated to realize the desired chirp and phase shifts simply and flexibly. A 44-pm-spaced dual-wavelength DFB fiber laser is then achieved experimentally, which is the narrowest spacing ever reported for a compact multiwavelength fiber laser.     

间隔双倍频移的可调谐多波长布里渊/铒光纤激光器

设计了一种结构简单的波长间隔双倍布里渊频移的可调谐多波长布里渊/铒光纤激光器。利用一个3 dB耦合器形成复合环形腔结构,使奇数阶斯托克斯信号被局限在一个腔内循环,仅有初始布里渊抽运信号和偶数阶的斯托克斯信号能够耦合输出,实现了波长间隔双倍布里渊频移的多波长输出。分析了不同布里渊抽运功率、不同980 nm抽运功率下激光器的输出特性。在布里渊抽运信号功率10 dBm,980 nm抽运功率110 mW的情况下,激光器在1555~1565 nm范围内获得了波长间隔0.176 nm的6个波长输出。     

Multiwavelength erbium-doped fiber ring laser incorporating an SOA-based phase Modulator

A novel room-temperature multiwavelength erbium-doped fiber (EDF) laser is demonstrated. Stable multiwavelength lasing at room temperature is realized by incorporating a semiconductor optical amplifier (SOA)-based phase modulator in the laser cavity. The SOA is biased below the transparent point with a sinusoidal signal applied to achieve phase modulation, to suppress the homogenous line broadening of the EDF. Stable multiwavelength lasing with wavelengths up to 26 and wavelength spacing as small as 0.19 nm is demonstrated at room temperature.     

基于受激布里渊散射的可调谐多波长激光器

可调谐多波长布里渊掺铒光纤激光器将光纤中的SBS非线性放大同掺铒光纤的线性放大相结合得到室温稳定的多波长输出,具有波长间隔一致、线宽窄、功率谱相对平坦等优点。设计了一种基于光纤布拉格(FBG)反射的线性可调谐多波长布里渊掺铒光纤激光器。该线性腔激光器的一端利用光纤布拉格光栅作为反射镜,有效抑制了腔内自激模的影响,增加激光器输出波长数。布里渊泵浦信号进入布里渊增益介质之前经过掺铒光纤放大器的两次放大,降低了布里渊增益的阈值。该多波长激光器实现了1 530～1 560 nm之间30 nm可调谐范围的输出。在布里渊泵浦信号功率2 mW,980 nm泵源抽运功率60 mW情况下,1 540～1 554 nm范围内,获得了波长间隔0.088 nm的16个波长的输出。     

Multiwavelength Mode-Locked Fiber-Ring Laser Based on Reflective Semiconductor Optical Amplifiers

An active multiwavelength mode-locked fiber ring laser is demonstrated by exploiting cross-gain modulation in a reflective semiconductor optical amplifier. A length of dispersion-compensation fiber is incorporated in the ring cavity to enhance the multiwavelength performance. Simultaneous tunable triple-wavelength mode-locking is implemented with the pulse repetition of 10 GHz and wavelength spacing of 1.12 nm. The results provide an effective approach to fulfill all-optical clock recovery and data pattern conversion in multiwavelength for future optical communication systems.     

Sampled grating DBR laser arrays with adjustable 0.8/1.6 nmwavelength spacing

The difficulty in fabricating multiwavelength laser arrays with uniform wavelength spacing is overcome by using sampled grating distributed Bragg reflector (DBR) lasers as the constituent of a laser array. The sampling periods of the DBR mirrors are varied from laser to laser to provide reflection combs with different spacings in wavelength. Arrays of twelve lasers have been successfully fabricated with a single holographic exposure step. The wavelength spacing among the lasers can be adjusted to be around 0.8 or 1.6 nm with a simple tuning mechanism     

Multiwavelength DFB laser array transmitters for ONTCreconfigurable optical network testbed

We discuss the design, fabrication, and performance of experimental multiwavelength laser array transmitters that have been used in the reconfigurable optical network testbed for the Optical Network Technology Consortium (ONTC). The experimental four-node multiwavelength network testbed is SONET/ATM compatible. It has employed multiwavelength DFB laser arrays with 4 nm wavelength spacing for the first time. The testbed has demonstrated that multiwavelength DFB laser arrays are indeed practical and reproducible. For the DFB laser arrays used in such a network the precise wavelength spacing in the array and the absolute wavelength control are the most challenging tasks. We have obtained wavelength accuracy better than ±0.35 nm for all lasers, with some registered to better than ±0.2 nm. We have also studied the array yield of our devices and used wavelength redundancy to improve the array yield. Coupling efficiencies between -2.1 to -4.5 dB for each wavelength channel have been obtained. It is achieved by using specially designed lensed fiber arrays placed on a silicon V-grooved substrate to exactly match the laser spacing. The transmitter consisted of a multichip module containing a DFB laser array, an eight-channel driver array based on GaAs IC's, and associated RF circuitry     

Tunable multiwavelength fiber laser employing a comb filter based on a polarization-diversity loop configuration

A tunable multiwavelength fiber laser based on a semiconductor optical amplifier (SOA) is newly proposed. The proposed fiber laser employs a fiber comb filter based on a polarization-diversity loop configuration (PDLC) for the multiwavelength selection. The spectral characteristic of the comb filter is graphically explained by tracing the state of polarization (SOP) of the light propagating through the filter on the Poincare sphere. Particularly, the method of adjusting the filter characteristics is established with the help of the Poincare-sphere representation. The experimental results show that 18 laser lines oscillate with the signal to amplified spontaneous emission noise ratio over 25 dB. Particularly, all of the laser lines with a fixed channel spacing of /spl sim/ 0.8 nm can be continuously shifted by adjusting only a wave plate contained within the filter.     

Multiwavelength Raman fiber-ring laser based on tunable cascaded long-period fiber gratings

Multiwavelength Raman fiber lasers using intracavity tunable cascaded long-period fiber gratings (LPFGs) are discussed. The application of the cascaded LPFGs as a multichannel fiber filter for the multiple-wavelength generation is proposed and experimentally demonstrated. The characteristics of multiwavelength fiber-ring lasers can be controlled by changing the physical parameters of cascaded LPFGs such as the separation distance between the gratings, grating length, and number of gratings. The multiwavelength Raman fiber-ring laser with nine wavelength-division-multiplexing channels with 100-GHz spacing and 19 channels with 50-GHz spacing has been achieved by varying the physical parameters of cascaded LPFGs.     

Multiwavelength Erbium-Doped Fiber Laser Employing Cavity Loss Modulation

A novel and simple multiwavelength erbium-doped fiber laser is proposed and demonstrated. The combination of a polarization scrambler and a polarizer is employed to induce polarization-dependent-loss modulation. The loss modulation induced multiwavelength lasing by alleviating the mode competition caused by homogeneous gain broadening of the erbium-doped fiber. As a result, 11-wavelength lasing operation with wavelength spacing of 0.8 nm has been achieved. The output power distribution is quite uniform and the power fluctuation of each wavelength is smaller than 0.6 dB.     

Multiwavelength Fiber Optical Parametric Oscillator

We demonstrate, for the first time to the best of our knowledge, a multiwavelength fiber ring laser using a continuous-wave dual-pump fiber optical parametric amplifier (FOPA) as gain medium. In the ring cavity, two high-power pumps are injected into a spool of 1-km highly nonlinear dispersion-shifted fiber to generate the parametric gain, and a superimposed chirped fiber Bragg grating is used as the comb-like filter. Benefiting from the high and flat gain of the dual-pump FOPA, seven lasing lines around 1.55 mum with wavelength spacing of 1 nm have been obtained. Each lasing line has a linewidth of as narrow as 20 pm and an extinction ratio of > 30 dB. The proposed mechanism using a dual-pump FOPA as gain medium is a promising alternative for generating multiwavelength laser.     

室温下稳定工作的多波长掺铒光纤激光器

对多波长掺铒光纤激光器进行了实验研究。通过在环形腔掺铒光纤激光器中引入一个全光纤相位调制器,在双折射光纤长度约为4．1m时,实现了室温下16个波长的稳定输出,波长间隔为0．8nm,满足ITU信道标准。而且通过改变双折射光纤的长度,可实现相邻时长间隔的精确调节。激射波长线宽小于0．1nm。功率谱比较平坦,在近12nm的谱宽内功率起伏小于dB。     

Multiwavelength tunable fiber ring laser based on sampled chirp fiber Bragg grating

We propose and experimentally demonstrate a novel configuration of a multiwavelength tunable fiber ring laser with equally increased or decreased wavelength spacing. Wavelength tuning is achieved by tuning the strain gradient of a sampled chirp fiber Bragg grating (SCFBG), which is integrated in the laser cavity. To achieve equally increased or decreased wavelength spacing, the SCFBG is surface-mounted at a slant onto one lateral side of a plate so that each wavelength-selective element of the SCFBG will experience an equal strain increment when an external force is applied to the plate. We experimentally obtain seven lasing wavelengths with equally increased or decreased wavelength spacing.     

窄线宽多波长掺铒光纤激光器

在掺铒光纤线型的单模光纤腔中接续一段多模光纤 ,依靠多模光纤中导模的空间模式跳动与激光谐振腔中的偏振烧孔共同作用 ,实现了窄线宽多波长的同时激射。激射波长的 3d B线宽约为 0 .0 9nm ,波长间隔为 0 .6 8nm。     

一种线形腔的多波长布里渊掺铒光纤激光器

布里渊掺铒光纤激光器(BEFL)是一种利用非线性效应——布里渊散射来实现多波长输出的激光器,波长间隔大约为0.088 nm(11 GHz).研究了一种多波长布里渊掺铒光纤激光器线形结构,通过引入反馈实现多波长输出.在布里渊泵浦功率为11 mW,980 nm泵浦功率为12 mW时获得了波长间隔为0.08 nm的34个波长的激光输出以及1 525～1 570 nm可调谐范围.并通过调节980 nm抽运光功率以及布里渊泵浦光波长,实现了可调谐的多波长输出.还研究了980 nm抽运光功率对产生的斯托克斯光波数的影响.     

Efficient technique for increasing the channel density in multiwavelength sampled fiber Bragg grating filters

We introduce a new class of high channel count multiwavelength comb filters based on sampled fiber Bragg gratings (FBGs). Our approach exploits the spectral fractional Talbot effect in sampled chirped FBGs (S-CFBGs). For specific conditions between the grating chirp and sampling period, the channel spacing can be reduced compared to the value obtained using conventional sampling techniques. In this way, the channel density can be multiplied without needing to increase the sampling period. Moreover, despite the fact that the grating is chirped, operating under the spectral Talbot regime ensures that the resultant in-band group delay characteristics are similar to those of a sampled uniform period FBG.     

室温稳定多波长光纤激光器技术的研究新进展

室温稳定的多波长光纤激光器( MWFL)中最关键的技术是如何有效抑制掺杂光纤的均匀展宽效应。综述了国际上近年来提出的实现室温稳定多波长光纤激射的主要技术。介绍了近几年我们在该领域的一些创新性研究工作:提出了多种基于多谐振峰的光纤布拉格光栅(FBG) ,如多模光纤布拉格光栅、保偏光纤布拉格光栅、取样光纤布拉格光栅等的可开关多波长光纤激光器的新方法和新结构,实现了多种波长间隔小于2 nm,室温工作稳定性好、波长及波长间隔可调的可开关多波长光纤激光器;提出了基于非线性光纤环镜( NOLM)和非线性偏振旋转(NPR)效应的两种多波长掺铒光纤激光器(EDFL)实现技术,实现了室温稳定、功率谱分布平坦的宽带多波长激光输出,3 dB带宽内的波长个数可达50个,每个波长的功率波动在2 h内小于0 .1 dB。     

多波长掺镱光纤线形腔激光器的实验研究

利用两个光纤环镜作为线形腔的端镜,在其中一个环镜中加入腔长可调的F-P腔构成梳状滤波器,从而产生波长间隔可调的多波长激光振荡.实验结果表明,当波长间隔大于1.3nm时,器件可以产生室温下稳定的多波长激光.