Wideband wavelength tunable fiber ring laser with flattened output power spectrum

A wavelength tunable erbium-doped fiber ring laser with flattened output power spectrum over a broadband is proposed and demonstrated. The power flattening is achieved using a high-birefringence fiber loop mirror, in which a number of high-birefringence fiber sections and polarization controllers are used to get a reflection spectrum that can compensate for the output power spectrum. The wavelength tuning is realized by compressing or stretching the FBGs in the laser cavity. A 1×3 switchable fiber Bragg grating array is incorporated into the fiber ring to get a wideband tuning range of 38 nm, from 1527 to 1565 nm. Within this range, the output power uniformity is controlled within ±0.8 dB. The total output power is about 4 dBm, the 3-dB linewidth is 0.01 nm, and the side mode suppression ratio is more than 48 dB.     

窄线宽高信噪比可调谐掺Er3+光纤激光器

基于偏振态调谐原理,利用多个偏振控制器在环形腔掺Er3+光纤激光器中实现了连续可调谐、窄线宽、高信噪比的单频激光输出.连续调谐宽度达22 nm (1538～1560 nm),3 dB谱线宽度小于0.1 nm,光信号-自发辐射噪音比大于45 dB,最大输出功率约1 mW.在10～50 mW泵浦功率范围内,输出功率波动幅度小于1 dB.在室温下,工作数十个小时,中心波长漂移小于0.05nm.     

Simple tunable multiwavelength Brillouin/Erbium fiber laser utilizing short-length photonic crystal fiber

We have demonstrated a simple ring cavity tunable multiwavelength Brillouin/Erbium fiber laser (MWBEFL), in which 70 m highly nonlinear photonic crystal fiber (HNL-PCF) is used as the Brillouin gain medium. The fiber laser utilizes recycling mechanism to enhance stimulated Brillouin scattering (SBS). The configuration that consists of only 3 optical components is easy to be integrated and improves the practicality. At the maximum 1480 nm pump power of 110 mW and the Brillouin pump power of 3 dBm, 10 stable output channels with more than 10 dB optical signal to noise ratio (OSNR) and 0.078 nm channel spacing could achieve 10 nm tuning ranges.     

Wavelength-tunable erbium fiber ring laser in single-frequency operation utilizing Fabry-Perot laser with Sagnac cavity

We propose and demonstrate experimentally a stabilized and wavelength-selective erbium-doped fiber ring laser in single-longitudinal-mode operation with Fabry-Perot laser diode (FP-LD) and using a tunable bandpass filter (TBF) inside and outside a Sagnac ring cavity. The side-mode suppression ratios of 21 dB and 36.5 dB and the output power of -3.6 dB m and -8.7 dB m in the wavelengths of 1524.45-1562.35 nm and 1531.07-1562.35 nm with the tuning step of 1.4 nm can be achieved when the TBF outside and inside Sagnac loop, respectively. The output wavelength variation of zero and the output power fluctuation of <0.1 dB are also obtained. Moreover, the transmission efficiency of the ring laser has also been performed experimentally under a 1.25, 2.5 and 10 Gb/s external modulation, respectively.     

Widely tunable Yb-doped laser with all fiber structure

In this paper, an all fiber Yb³⁺-doped fiber ring laser with large tuning range has been reported. A 976 nm laser diode (LD) pumped laser is used as the pump source and high concentration Yb³⁺-doped fiber is adopted as gain medium. Adjusting the polarization controller (PC), a widely tunable range of 20 nm from 1030 to 1050 nm is obtained. The spectral linewidth of the pulse is less than 0.2 nm. Comparing with other fiber laser structures, the fiber laser with an all-fiber structure has higher efficiency and better stability. The laser also has very stable and flat output within the whole tuning range.     

Widely tunable compact erbium-doped fiber ring laser for fiber-optic sensing applications

A compact erbium-doped ring-shaped fiber laser suitable for fiber-optic sensing applications has been developed. The fiber laser utilized a tunable fiber Fabry–Perot filter as the tuning element and had a moderate milli-Watt level power output over almost the whole tuning range from 1530 to 1595 nm with a power fluctuation of 0.15 dB. High repetition rate scanning of laser operation over the whole tuning range was achieved at rates of up to 200 Hz. Moreover, the performance of the ring-shaped fiber laser configured with a high-concentration erbium-doped fiber was investigated for its larger wavelength tunability of over 100 nm. Output power characteristics of this ring-shaped fiber laser were also investigated when it worked in a scanning mode. A distorted power wavelength dependence, as well as some pulsing phenomenon were observed in scanning mode.     

Dispersion-tuned multiwavelength actively mode-locked fiber laser using a hybrid gain medium

We demonstrate a multiwavelength 10 GHz pulse source using a dispersion-tuned actively mode-locked fiber ring laser incorporated with a semiconductor optical amplifier and an erbium-doped fiber amplifier. Simultaneous seven-wavelength operation of the laser is obtained. The side-mode suppression of all wavelengths is above 30 dB. Smooth wavelength tuning is achieved over more than 12 nm by changing the modulation frequency or the length of the optical delay line. Pulse characteristics are almost constant over the entire tuning span. Wavelength spacing can also be varied from 0.9 to 10 nm by adjusting the dispersion of the cavity. These experimental observations agree well with theoretical analyses.     

100nm宽光谱可调谐掺饵光纤激光器

采用1480 nm大功率激光二极管双向抽运,新型铋基掺饵光纤做增益介质,基于旋转法布里-珀罗腔的可调谐滤波器和带通滤波器做选频装置的宽光谱环形腔可调谐光纤激光器,可实现100 nm（1523~1623 nm）激光波长程控连续可调谐输出,激光输出功率大于1.58 mW,3 dB带宽小于0.1 nm,波长重复性准确度小于0.01 nm.     

Tunable dual-wavelength erbium-doped fiber ring laser covering both C-band and L-band for high-speed communications

A simple, continuously tunable dual-wavelength erbium-doped fiber ring laser (TDEDFL) structure for applications in high-speed communication systems is proposed and experimentally demonstrated. The dual-wavelength tuning range is 58 nm covering both the C-band and L-band from 1547 to 1605 nm. We can not only obtain a 45% improvement over previously reported tuning ranges, but also tune the wavelength of each lasing output independently. The power equalization of the dual-wavelength outputs is less than 1.5 dB. We obtain extremely stable power variation and wavelength fluctuation at room temperature. Using this fiber laser, a 10-Gb/s data transmission over a 25-km single-mode fiber (SMF) can be made available with a power penalty of 0.5 dB is demonstrated with this laser.     

Widely tunable mode-locked all-fiberized Yb-doped fiber laser with near-transform-limited spectrum linewidth

A widely tunable mode-locked all-fiberized Yb-doped fiber laser with near-transform-limited spectrum linewidth is used. It consists of a tunable fiber Bragg grating (TFBG) and a fiber-coupled LiNbO₃ phase modulator (PM) in a linear cavity. The TFBG is used to achieve tunable emission wavelength, and the intracavity PM is used to achieve actively mode-locking operation. We have experimentally demonstrated that the laser-emitting wavelength can be tuned between 1,041 and 1,091 nm with power fluctuation less than 3 dB. The temporal width of the laser pulse is about 1 ns, and the pulses are near transform-limited with a spectral linewidth of 1.3 GHz. The results may find useful application in optical communication and optical measurement system.     

Tunable erbium doped fiber ring laser using fiber Bragg grating-assisted add-drop filter

A stable and low costless tunable erbium doped fiber ring laser using fiber Bragg grating-assisted add-drop filter is proposed and demonstrated. A stable laser output is obtained with a 4 nm tuning range. The power fluctuation, full-width at half maximum and SMSR are measured to be less than 0.50 dB, smaller than 0.015 nm and better than 55 dB in this tuning range.     

Multiwavelength self-seeded Brillouin-erbium fiber laser with 45-nm tunable range

We have demonstrated a tunable multiwavelength self-seeded Brillouin-erbium fiber laser (BEFL) without externally Brillouin pumping. In this scheme, the stable multiwavelength comb can be produced within a ∼45-nm wavelength tuning range through adjusting the polarization controllers (PCs) in a high-birefringent Sagnac loop mirror. The generation of ∼200-line Stokes comb has been achieved by adjusting PCs under bidirectional pumping of two laser diodes, which is the largest wavelength number to the best of our knowledge. The effect of 980 nm pump power on the multiwavelength generation was also investigated.     

稳定可调谐的单纵模多环形腔掺铒光纤激光器

提出了一种多环形腔(MRC)结构的稳定可调的单纵模(SLM)掺铒光纤激光器,多环形腔结构由双环形有源腔和两个次级无源腔组成.这种激光器是利用光纤法布里珀罗可调滤波器(FFP-TF)以及光学光栅滤波器(OGF)两种滤波器和多环形腔结构相结合来共同选模.可实现波长调节范围为1528～1565 nm,在整个波长调节范围内边模抑制比大于44.53 dB,在1554 nm附近边模抑制比可以达到最大值51.18 dB, 输出功率为-8.84 dBm,通过应用多环型腔结构,激光器的输出很稳定,在18 min的观察时间内,中心波长的变化小于0.02 nm,输出功率的变化小于0.04 dBm,实现了稳定且可调谐的单纵模输出.     

High stable single-polarization tunable fiber laser based on Opto-DMD processor and polarization-maintaining fiber devices

A high stable wavelength-tunable fiber laser is experimentally demonstrated by using a digital-micromirror-device (DMD) processor and a polarization-maintaining erbium-doped fiber amplifier (EDFA).The electronic-addressed DMD processor is able to select and couple a waveband from of the polarization-maintaining EDFA back into the fiber ring to generate a narrow line-width laser output. The tunable fiber laser shows a line-width of 0.02 nm, a tuning step of 0.08 nm over the c-band and a side mode suppression ratio (SMSR) greater than 50 dB. The output power uniformity of 0.01 mW is achieved by using the automatic power control (APC) system under room temperature. The center wavelength fluctuation during 1 h is below 0.01 nm.     

Tunable multi-wavelength fiber laser based on a polarization-maintaining erbium-doped fiber and a polarization controller

A stable and tunable multi-wavelength fiber laser with a polarization-maintaining erbium-doped fiber (PM-EDF) and a polarization controller (PC) is proposed and demonstrated. A homemade PM-EDF incorporated in the ring cavity is used as the gain medium. Simultaneous multi-wavelength oscillation is achieved at room temperature. The theory of the PM-EDF and PC to suppress the wavelength competition is described in detail. The 3 dB bandwidth is less than 0.01 nm. The power fluctuation and wavelength shift are measured to be less than 0.5 dB and 0.05 nm over 32 min. The wavelength tuning between single-, double-, triple-, and four-wavelength is realized.     

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.     

A compact graphene Q-switched erbium-doped fiber laser using optical circulator and tunable fiber Bragg grating

We demonstrate a passively Q-switched tunable erbium-doped fiber laser(EDFL)based on graphene as a saturable absorber(SA).A three-port optical circulator(OC)and a strain-induced tunable fiber Bragg grating(TFBG)are used as the two end mirrors in an all-fiber linear cavity.The Q-switched EDFL has a low pump threshold of 23.8 mW.The pulse repetition rate of the fiber laser can be widely changed from 9.3 kHz to 69.7 kHz by increasing the pump power from23.8 mW to 219.9 mW.The minimum pulse duration is 1.7μs and the highest pulse energy is 25.4 nJ.The emission wavelength of the laser can be tuned from 1560.43 nm to 1566.27 nm by changing the central wavelength of the straininduced TFBG.     

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.     

高功率宽调谐范围掺Yb3+光子晶体光纤激光器

采用闪耀光栅作为色散元件,构建了前向、后向输出两种结构的可调谐掺Yb3 光子晶体光纤激光器,并对其输出特性进行了分析研究.在抽运功率5.75W时,前向输出结构实现了1050.6～1110.2 nm的连续调谐输出,光谱线宽约0.1 nm,边模抑制比大于44 dB.在调谐激光波长为1085 nm时,得到最高输出功率677 mW.结构改进的后向输出结构的可调谐输出结构在抽运功率4.43 W,调谐波长1075 nm,实现了2.21 W的功率输出,斜率效率为73%;调谐范围50.9 nm(1042.1～1093 nm),光谱线宽小于0.08 nm,边模抑制比大于50 dB.两种结构的可调谐激光器输出均为线偏振光,偏振度大于89.5%.     

C- and L-band tunable fiber ring laser using a two-taper Mach-Zehnder interferometer filter

A stable C- and L-band tunable fiber ring laser, using a two-taper Mach-Zehnder interferometer (MZI) as a filter, is proposed and demonstrated experimentally. One of the two taper waists is mechanically bent to tune the laser wavelength. Being amplified by an L-band erbium-doped fiber amplifier and an erbium-doped fiber, respectively, the fiber ring laser has a full L-band (1564-1605nm) and C-band (1550-1565nm) tuning range with a side-mode suppression ratio as high as 50dB. The laser linewidth and the minimum tuning step are related to the MZI's cavity length. It was also found that thermal annealing relieved the internal stresses of the tapers and greatly improved the laser performance.