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华南理工大学杨中民窄线宽光纤激光器 2010

An efficient compact 300 mW narrow-linewidth single frequency fiber laser at 1.5 μm

S. H. Xu, Z. M. Yang, T. Liu, W. N. Zhang, Z. M. Feng, Q. Y. Zhang *,

and Z. H. Jiang

Institute of Optical Communication Materials, South China University of Technology, GuangZhou 510641, P. R. China

* qyzhang@https://www.wendangku.net/doc/523661845.html,

Abstract: An efficient single frequency fiber laser by using a

newly-developed Er3+/Yb3+ co-doped single mode phosphate glass fiber with

the net gain coefficient of 5.2 dB/cm and propagation loss coefficient of 0.04

dB/cm has been demonstrated. Over 300 mW stable continuous -wave single

transverse and longitudinal mode seed lasering at 1.5 μm has been achieved

from a 2.0 cm-long active fiber. The measured slope efficiency and the

calculated quantum efficiency of laser emission are found to be 30.9% and

0.938 ± 0.081, respectively. It is found that the linewidth of the fiber laser is

less than 2 kHz, and the measured relative intensity noise (RIN) is around

?120 dB/Hz in the frequency range of 50 to 500 kHz.

? 2010 Optical Society of America

OCIS codes: (140.3510) Lasers, fiber; (060.2280) Fiber design and fabrication; (060.2410)

Fibers, erbium

References and links

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telecommunication systems,” IEEE Photon. Technol. Lett. 10(8), 1109–1111 (1998).

2. J. Geng, C. Spiegelberg, and S. Jiang, “Narrow linewidth Fiber laser for 100-km optical. frequency domain

reflectometry,” IEEE Photon. Technol. Lett. 17(9), 1827–1829 (2005).

3. C. V. Poulsen, P. Varming, J. E. Pedersen, M. Beukema, S. L. Lauridsen, “Applications of single frequency fiber

lasers,” Lasers and Electro-Optics Europe, 2003 CLEO/Europe, 617 (2003)

4. M. Leigh, W. Shi, J. Zong, Z. Yao, S. Jiang, and N. Peyghambarian, “High peak power single frequency pulses

using a short polarization-maintaining phosphate glass fiber with a large core,” Appl. Phys. Lett. 92(18), 181108 (2008).

5. T. Qiu, S. Suzuki, A. Schülzgen, L. Li, A. Polynkin, V. Temyanko, J. V. Moloney, and N. Peyghambarian,

“Generation of watt-level single-longitudinal-mode output from cladding-pumped short fiber lasers,” Opt. Lett.

30(20), 2748–2750 (2005).

6. M. Leigh, W. Shi, J. Zong, J. Wang, S. Jiang, and N. Peyghambarian, “Compact, single-frequency all-fiber

Q-switched laser at 1 microm,” Opt. Lett. 32(8), 897–899 (2007).

7. C. Spiegelberg, J. Geng, Y. Hu, T. Luo, Y. Kaneda, J. Wang, W. Li, M. Brutsch, S. Hocde, M. Chen, J. Babico, K.

Barry, W. Eaton, M. Blake, D. Eigen, I. Song, and S. Jiang, “Compact 100 mW fiber laser with 2 kHz linewidth,”

OFC 3, PD45–P1-3 (2003).

8. C. Spiegelberg, J. Geng, Y. Hu, Y. Kaneda, S. Jiang, and N. Peyghambarian, “Low-noise narrow-linewidth fiber

laser at 1550 nm (June 2003),” J. Lightwave Technol. 22(1), 57–62 (2004).

9. B. C. Hwang, S. Jiang, T. Luo, F. Smekatala, J. Watson, G. Sorbello, and N. Peyghambarian, “Cooperative

upconversion and energy transfer of new high Er3+- and Yb3+–Er3+-doped phosphate glasses,” J. Opt. Soc. Am. B 17(5), 833 (2000).

10. S. H. Xu, Z. M. Yang, Z. M. Feng, Q. Y. Zhang, Z. H. Jiang, and W. C. Xu, “Efficient fibre smplifiers based on a

highly Er3+/Yb3+ codoped phosphate glass-fibre,” Chin. Phys. Lett. 26(4), 047806 (2009).

11. S. Jiang, S. Mendes, Y. Hu, S. Nunzi-Conti, A. Chavez, Y. Kaneda, T. Luo, S. Hodce, D. Nguyen, E. Wright, and J.

Wang, W. T. Gian, T. Nikolajsen, and N. Peyghambarian, “Compact multimode pumped erbium-doped phosphate fiber amplifers,” Opt. Eng. 42, 2817 (2003).

12. S. H. Xu, Z. M. Yang, Z. M. Feng, Q. Y. Zhang, Z. H. Jiang, and W. C. Xu, “Gain and noise characteristics of

single-mode Er3+/Yb3+ co-doped phosphate glass fibers,” 2nd IEEE International Nanoelectronics Conference 1–3, 633 (2008)

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“Performance of high-concentration Er3+-Yb3+-codoped phosphate fiber amplifiers,” IEEE Photon. Technol. Lett.

13(7), 657–659 (2001).

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quantum efficiency and heat generation in Nd3+-doped materials,” Opt. Express 13(6), 2040–2046 (2005).

15. M. Karasek, “Optimum design of Er3+-Yb3+ codoped fibers for large-signal high-pump-power applications,” IEEE

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16. T. Liu, Z. M. Yang, and S. H. Xu, “3-Dimensional heat analysis in short-length Er3+/Yb3+ co-doped phosphate fiber

laser with upconversion,” Opt. Express 17(1), 235–247 (2009).

17. W. L. Barnes, P. R. Morkel, L. Reekie, and D. N. Payne, “High-quantum-efficiency Er(3+) fiber lasers pumped at

980 nm,” Opt. Lett. 14(18), 1002–1004 (1989).

1. Introduction

Single frequency fiber laser has been the subject of intense research in the last two decades for applications, such as high resolution sensing, coherent telecommunication, optical frequency domain reflectometry, and as a seed laser for LIDAR [1–3]. Of these short resonance cavity configuration, such as distributed Bragg reflector (DBR), is beneficial to single frequency laser emission for mode-hop free, narrower linewidth, lower noise, and all in a compact all- fiber design [4–8]. Recently, Spiegelberg et al have reported DBR laser emission around 1550 nm in Er3+/Yb3+ co-doped phosphate glass fibers [7,8]. Single frequency laser with the output power of over 200 mW and the linewidth of < 2 kHz has been achieved from a 2-cm-length phosphate glass fiber by the authors. However, the effective length of the resonator is designed to be 5 cm, which easily leads to multi-longitude emissions. In order to select one longitudinal mode, the linear cavity should be shortened further or a composite fiber grating should be adopted. Shortening the resonance cavity will limit the laser output power and thus higher concentrations of rare-earth ions should be doped into the glass fiber core. Furthermore, the upconversion effects will be more serious with the increase of the concentrations of rare-earth ions [9], and a great deal of heat generated will decrease the quantum efficiency further. Therefore, developing the Er3+/Yb3+ co-doped phosphate glass fiber with high gain coefficient and low propagation loss and low heat accumulation are key points to achieve efficient single frequency lasers.

Recently, we have reported that a homemade 3.0 cm Er3+/Yb3+-codoped phosphate glass fiber could provide an internal gain up to 36 dB [10]. Here we report a more efficient and compact single frequency fiber laser with high output power and narrow linewidth based on our newly-developed Er3+/Yb3+-codoped phosphate single mode glass fibers and the 3D short-cavity heat flow model.

2. Active fiber and single frequency fiber laser design

RE ions were doped uniformly in the core region with concentrations of 3.0mol% for Er3+, and 5.0mol% for Yb3+, respectively. The fluorescence lifetime of the 4I13/2-4I15/2 transition of Er3+ ions is 8.1 ms in a phosphate fiber 4 mm in length. The absorption and emission cross sections are 5.96 × 10?21 cm2, and 7.17 × 10?21 cm2 at 1534 nm, respectively. The refractive index of the core and cladding glass are measured to be 1.535 and 1.522 via a prism coupler (Metricon Model 2010) at 1310 nm, respectively. The phosphate glass fiber designed has a core diameter of 5.4 μm with a numerical aperture (NA) of 0.206 at 1.5 μm. The Er3+/Yb3+-codoped phosphate glass fiber was fabricated using a fiber-drawing tower (TDR-2, Japan) based on the rod-in-tube technique [10]. The cross section of the phosphate glass fiber is detected via an amplified CCD viewer, as shown in the inset of Fig. 1. The core-to-cladding offset is less than 0.4 μm. The mode-field diameter at 1550 nm is estimated to be 6.24 μm and the cut-off wavelength was calculated to be 1470 nm. The average propagation loss measured by the cut-back method is lower than 0.04 dB/cm at 1310nm, which is the lowest value reported in this kind of fiber [7,8,10–13]. The gain and noise figure characteristics of the Er3+/Yb3+-codoped phosphate glass fiber have been demonstrated, as shown in Fig. 1. A net gain per unit length of up to 5.2 dB/cm at 1535 nm was obtained from a 40-mm-length Er3+/Yb3+-codoped phosphate glass fiber, which is the highest gain coefficient reported in this kind of fiber [7,8,10–13]. The obtained noise figures of different signal wavelengths from 1525 nm to 1565 nm were less than 5.5 dB.

15201530154015501560157005

101520

G a i n (d B )Wavelength (nm)

N o i s e F i g u r e (d B )

Fig. 1. Gain and noise figure characteristics of the Er 3+/Yb 3+ codoped phosphate glass fiber.

Inset: the cross section of the phosphate glass fiber. Pump power P p = 330.8 mW,

signal input power P in = ?30 dBm, fiber length 40 mm.

A laser cavity is established by one spectrally narrow band fiber Bragg grating (NB-FBG) and one dielectric mirror that is butt-coupled to the one end facet of

a short piece of Er 3+/Y

b 3+-codoped phosphate fiber, as shown in Fig. 2. The NB-FBG with a 3-dB linewidth of 0.06 nm and a center-wavelength reflectivity 50.5% has been fabricated. The reflectivity of

Fig. 2. Experimental setup of compact short Er 3+/Yb 3+ co-doped phosphate fiber laser.

the dielectric mirror is larger than 99.5% at the signal wavelength of 1535 nm and smaller than 5% at the pump wavelength of 976 nm, which can diminish the pump light back to the pump laser diodes (LDs) and thus reduces the instability of the pump source. In order to improve the pump/signal coupling efficiency further, the NB-FBG had been irradiated in the Corning HI 1060 FLEX fiber with a mode-field diameter of 6.3μm at 1550 nm and 4.0μm at 976 nm. The NB-FBG was fused splicing with the 2-cm long phosphate fiber. The effective length of the resonator includes the 2.0 cm active fiber and a half of the 1.5 cm NB-FBG irradiated area. It is less than 3 cm, giving a longitudinal mode spacing of 3.4 GHz. The NB-FBG has a reflection bandwidth of less than 7.5 GHz, supporting only one longitudinal mode. The laser cavity was assembled into a copper tube, which was temperature-controlled by a cooling system with the resolution of 0.05°C. With a proper temperature control, the laser will operate in a single frequency without mode hop and mode competition phenomena. Two high power 976 nm FBG-stabilized pump lasers (PL1 and PL2) with orthogonal polarization output were combined through a polarization beam combiner (PBC). The pump lasers are coupled into the laser cavity through a 980/1550 nm WDM. The emission spectrum and the optical power of fiber laser is (C) 2010 OSA 18 January 2010 / Vol. 18, No. 2 / OPTICS EXPRESS 1251#119310 - $15.00 USD Received 30 Oct 2009; revised 27 Dec 2009; accepted 30 Dec 2009; published 11 Jan 2010

measured by an optical spectrum analyser (OSA, Anritsu MS9710C) and a power meter (PM, Ophir NovaII), respectively.

3. Single-frequency fiber laser performance

Figure 3 shows the laser output power at 1.5 μm from the Er 3+/Yb 3+-codoped phosphate glass fiber versus the pump power. The lasing threshold is around 80 mW. When the pump power is above the threshold, the laser output power is linearly enhanced with increasing the pump power. A maximum output power of 306 mW has been achieved from the 2.0 cm phosphate fiber at the pump power of 1072 mW, which is, to the best of our knowledge, the highest output power from this kind of fiber lasers reported to date. [7-12] The slope efficiency of the laser emission is measured to be 30.9% and the experimental quantum efficiency of the laser emission related to the absorbed pump power is estimated to be 58% since only 84% of the pump power is coupled into the phosphate fibre core due to the coupling loss, scattering, and pump leakage. It should be pointed out that the pump power illustrated in Fig. 3 is the nominal power before coupling into the WDM. No output power saturation phenomenon is observed, indicating that the output power will rise further with increasing the pump power. The center wavelength of laser emission spectrum of 1534.75 nm and the side mode suppression ratio (SMSR) of > 65 dB has been measured by the OSA. The transient fluctuations of the output power at 250 mW have been investigated as shown in the inset of Fig. 3. The output power fluctuations of < ± 0.18% of the average power were observed, which is caused by the small fluctuations in the pump laser power. Meanwhile, we have measured the long-term stability of the output power over 40 h. If the ambient temperature is held 23°C, the output power fluctuations were less than ± 0.5% over the entire period of time.

02004006008001000 F i b e r L a s e r O u t p u t P o w e r (m W ) Pump Power (mW)

Fig. 3. Output power of the single frequency fiber laser versus pump power. Inset: the transient

fluctuations of the fiber laser output power.

In order to assess the performance of Er 3+/Yb 3+ co-doped glass fiber and intend to further increase the laser output power, it is necessary to evaluate the quantum efficiency φ without and with laser action, the former is fluorescence quantum efficiency and the latter is defined as the fraction of emitted photons by the absorbed photons. Without laser action the fluorescence quantum efficiency (the ratio between its radiative and total rates) is given as φ = τ/τrad [14], and the value is gotten to be ~0.903. The fractional thermal loading η can be determined by the quantum efficiency φ as η = 1?φ (λex / <λem >) and the value is 0.431. With laser emission the quantum efficiency φ in fiber laser can be expressed as [15]:

1/p s s a

h P T h P ν?ν= where T 1 is the transmission coefficient of the output coupler. P s is the output power of signal light. νp and νs are the pump and signal frequency, respectively. P a is the fraction of the pump power absorbed which is determined theoretically based on the space-dependent rate equations for the Er 3+ and Yb 3+ population densities [16]. Figure 4 show the quantum efficiency in different pump power above the threshold value. The average quantum efficiency is found to be 0.938 ± 0.081 in our laser system, which is nearly the same as the Er 3+ doped fiber laser reported by Barnes [17]. The results show that an efficient energy-transfer exists in the Er 3+/Yb 3+ codoped phosphate glass fiber.

Q u a n t u m E f f i c i e n c y Pump Power (mW)

Fig. 4 Quantum efficiency vs pump power above the threshold value.

The single frequency operation was verified by a scanning Fabry–Pérot spectrum analyzer that had a free spectral range of 300 MHz and a finesse of 300. In order to further investigate the laser spectral characteristics, the linewidth of

the fiber laser was measured by the self-homodyne method using a 48.8-km-fiber delay. Figure 5 shows the homodyne signal

R F P o w e r (d B m )Frequency (kHz)

Fig. 5. The lineshape of the homodyne signal measured with 48.8 km fiber-delay and the laser

linewidth is approximately 1.6 kHz FWHM.

spectrum of the fiber laser measured by a radio frequency (RF) electrical spectrum analyzer (ESA, Aglient N9320A). It is 32 kHz with ?20 dB from the peak, which indicates the laser linewidth is approximately 1.6 kHz FWHM. The rise at the zero frequency is caused by the RF (C) 2010 OSA 18 January 2010 / Vol. 18, No. 2 / OPTICS EXPRESS 1253#119310 - $15.00 USD Received 30 Oct 2009; revised 27 Dec 2009; accepted 30 Dec 2009; published 11 Jan 2010

spectrum analyzer. The fall at low frequencies below 2 kHz is caused by the low-frequency filter in the photoreceiver. 0100200300400500

-160-140

-120

-100-80

-60

R I N (d B /H z )Frequency (kHz)

Fig. 6. The relative intensity noise (RIN) of the fiber laser.

The relative intensity noise (RIN) of the fiber laser has been measured and is shown in Fig.

6. The RIN at the low frequencies of < 50 kHz decreases from ?86 dB/Hz to ?120 dB/Hz with increasing the frequency and is stabilized at approximately ?120 dB/Hz for frequencies above 50 kHz. The peak of RIN is observed at the several kHz, which is mainly caused by the ambient acoustics and vibration. The peak of the relaxation oscillation frequency of the fiber laser hasn’t been observed at the frequencies of < 500kHz.

4. Conclusions

In summary, we have demonstrated a 300 mW narrow linewidth fiber laser at 1.5 μm from an 2.0-cm short-length Er 3+/Yb 3+ heavily doped phosphate fiber. The fiber laser operates at a single frequency with the linewidth less than 2 kHz and the slope efficiency is 30.9%. The relative intensity noise (RIN) of the fiber laser is found to be ?120 dB/Hz for frequencies above 50 kHz. The results indicate that the Er 3+/Yb 3+-codoped phosphate single mode glass fiber might be a promising candidate as an efficient narrow-linewidth single frequency fiber laser.

Acknowledgement

The authors would like to acknowledge support from the NSFC (Grant Nos. U0934001 and 60977060).

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1550nm窄线宽激光器

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封装尺寸引脚定义01

引脚定义02

窄线宽光纤激光器的应用

窄线宽光纤激光器的应用单频光纤激光器具有线宽超窄、频率可调、相干长度超长以及噪声超低等独特性能，借用微波雷达上的FMCW技术可对超远距离的目标进行超高精度的相干探测，从而会改变市场对光纤传感、激光雷达和激光测距等固有观念，继续把激光器应用革命进行到底。光库通讯提供的单频光纤激光器拥有世界上独一无二的美国专利技术，可以十分低地成本解决激光光束质量和激光功率的矛盾，从而研制出了该款极具竞争优势的单频可调光纤激光器。关键词：5cm腔长 FMCW 混频相干探测 AFR光纤激光器的特点光库通讯提供的1550nm光纤激光器最大的特点就是线宽超窄至2Khz，频率稳定性好于10Mhz，具有超长相干长度和超低噪声，就是比世界上最好的DFB激光器都高出2个数量级。该款激光器输出功率可达150mW，边模抑制比高于50dB，热调协范围20Ghz，同时兼备50Mhz/V的线性PZT调制功能。除了对人眼安全的1550nm激光器外，光库通讯还提供同样性能的1000nm左右的光纤激光器，同时2000nm 的光纤激光器也正在计划之中。将来，光库通讯还会推出波长覆盖1000-1550nm全光纤化的单频、高功率脉冲光纤激光器。欢迎您的关注。核心技术请见图1为我们激光器的结构图，激光器腔由左右两端的光纤光栅和中间极短的有源光纤组成。该设计方案充分利用了我们美国合作方的专利技术，高浓度、铒/镱离子共掺有源光纤可以确保我们的激光器的腔长度少于5cm，这是传统光纤技术所不可能完成的任务！如此短的腔长极合适超高稳定性和跳模自由的单频激光工作。该种激光器的线宽典型值为2Khz，而且都是线偏光输出。结构紧凑和高稳定性能的光纤激光器就可以在如此短的激光腔基础上完成制作。图1：激光器结构在光纤传感中的应用光库通讯的超窄线宽光纤激光器可以应用于分布式光纤传感系统，对远至10公里的目标进行探测、定位和分类。它的基本应用原理就是频率调制连续波技术（FMCW），该技术能为核电站，石油/天然气管道，军事基地以及国防边界提供低成本的、全分布式的传感安全保护。在FMCW技术中，激光输出频率围绕它的中心频率不断变化，而激光的一部分光被耦合进一个有固定反射率的参考臂中，在外差相干探测系统中，该参考臂就充当了一个本地振荡器（LO）的作用。充当传感作用的是另一跟很长的光纤，请见图2。从传感光纤反射回来的激光与来自本地振荡器的参考光一起混合产生一个光拍频，该频率与它所经历的时间延迟差相对应。传感光纤上的远处信息就可以通过测量光谱分析仪上的光电流的拍频来获取。传感光纤上的分布式反射可以是最简单的瑞利后向散射。通过这种相干探测技术，

窄线宽可调谐半导体激光器的驱动电路

盐城师范学院毕业论文 (2011－2012学年度) 物电学院电子信息工程专业班级08（3）学号08223129 课题名称窄线宽可调谐半导体激光器的驱动电路学生姓名蒋峰指导教师沈法华

2012年5月20日

目录 1、绪论 (4) 2、工作原理 (5) 2.1半导体激光器原理 (5) 2.2窄线宽原理 (7) 2.3可调谐原理 (9) 2.3.1 基于电流控制技术 (9) 2.3.2 基于机械控制技术 (10) 2.3.3 基于温度控制技术 (10) 3、特性参数 (10) 3.1工作波长 (10) 3.2光谱宽度 (11) 3.3功率特性 (11) 3.3.1 小功率 (11) 3.3.2 高功率 (11) 3.4频率稳定性 (12) 4、可调谐半导体激光器的高精密驱动电源与稳频电路设计 (12) 4.1半导体激光器电路设计原理与实现 (12) 4.1.1 半导体激光器驱动方式简介 (12) 4.1.2 电路设计指标 (13) 4.1.3 驱动电路设计 (14) 4.2控温电路的设计与实现 (15) 4.2.1 基准采样电路 (15) 4.2.2 差分放大电路 (15) 4.2.3 自动控制电路 (15) 4.3控流电路的设计与实现 (16) 4.4微分稳频电路的设计与实现 (16) 总结 .................................................................................................. 错误！未定义书签。致谢 . (18) 参考文献 (18)

846nm半导体激光器线宽压窄的研究

文章编号:1673-0291(2007)06-0042-04 846nm 半导体激光器线宽压窄的研究苏展1,何世均1,沈乃 2 ,于闯3 (1.河南省自动化工程技术研究中心,郑州450008;2.中国科学院物理研究所,北京100080; 3.北京大学信息科学技术学院,北京100081) 摘要:研制了用于倍频蓝光的单模、可调谐的窄线宽光栅外腔反馈半导体激光器,它是由激光器底座、激光管组件、准直透镜组件和光栅组成.经过精密控制电流和温度,利用光栅反馈可获得激光单纵模输出,外腔的结构还使输出光的谱线宽度得以压窄.对研制的半导体激光器的特性测试表明,其输出功率稳定,阈值变小,模式单一稳定,波长可调谐,谱线宽度小于1MHz.关键词:激光技术;外腔半导体激光器;外腔光栅反馈;单纵模;窄线宽中图分类号:TN24814 文献标志码:A Research on Narrow Line Width External Cavity 846nm Semiconductor Laser S U Zhan 1 ,HE Shi -j un 2 ,SH EN Nai -cheng 2 ,Y U Chuang 3 (1.Henan Automat ion Eng ineering and T echnology Research Center,Zhengzhou 450008,China; 2.Institute of Physics Chinese Academy of Sciences,Beijing 100080,China; 3.Schoo l of Electronics Engineering and Computer Science,Peking U niversit y,Beijing 100081,China) Abstract:A single narrow line w idth tunable external cavity feedback sem iconductor used in frequency doubling blue light is proposed.It is constructed w ith laser base,laser tube,collimation system ,and optical grating.Via the current and temperature precise control,It is selected the mode of semiconduc -tor laser used in the feedback of grating.The structure of external cav ity makes the spectral line w idth of output lig ht to be narrowed.T hus a single long itudinal mode,narrow spectral line w idth and stable frequency external cavity semiconductor laser is realized,and its spectral line w idth is compressed to be less than 1MHz. Key words:laser technology;external cavity sem iconductor laser;ex ternal cav ity optical grating feed -back;sing le longitudinal mode;narrow line w idth 钙原子在657nm 上的吸收谱,是2003年国际长度咨询委员会(CCL)的13种国际推荐谱线之一.由于所要观测的钙束原子速度过大,导致检测效率的降低,但可利用钙原子在423nm 上的能级跃迁, 采取能级变换的方法来提高检测效率[1-4] .文中论述的846nm 的半导体激光可以借助铌酸钾晶体的非线性效应获得倍频423nm 的蓝光. 半导体激光器以其体积小、寿命长、使用简单方便等优点广泛应用于各个领域.尤其是外腔半导体激光器,其线宽可压窄1~2个量级,还可以将辐射变成单纵模输出,通过旋转光栅可以获得大范围连续可调谐的激光输出[5-7] . 利用外腔光栅反馈技术结合电流和温度的有效控制可以使外腔选模的846nm 半导体激光器的线宽压窄至小于110MHz 左右,此线宽完全可以满足对激光光源要求较高的科研工作. 收稿日期:2006-07-14 作者简介:苏展(1977)),男,河南许昌人,硕士.email:04121511@https://www.wendangku.net/doc/523661845.html, 第31卷第6期 2007年12月北京交通大学学报 JOU RN AL O F BEIJIN G JIAOT O NG U N IV ERSI T Y V ol.31N o.6Dec.2007

1550nm高效窄线宽光纤激光器

1550nm高效窄线宽光纤激光器** 伍波**,刘永智,刘爽,张谦述,代志勇 (电子科技大学光电信息学院,四川成都610054) 摘要:研制了一种采用双光纤光栅法布里-珀罗(FBG F-P)腔选模的线形腔结构窄线宽光纤激光器。激光器以高掺杂Er3+光纤为增益介质,结合非相干技术,利用全光纤型法拉第旋转器(FR)抑制空间烧孔效应,通过2个短FBG F-P腔选模,产生了稳定的1550nm单频激光输出。采用两端976nm LD抽运方式,阈值抽运光功率为11mW,在抽运光功率为145mW时输出信号光功率为73mW。光-光转换效率为50%,斜率效率达55%。采用延迟自外差方法精确测量光纤激光器线宽,实验中使用了10km单模光纤延迟线,由于测量精度的限制,得到线宽小于10kH z。研究表明,这种光纤激光器具有输出功率高、线宽窄和信噪比高的特点,可用于高精度的光纤传感器系统。关键词:激光技术;光纤激光器;窄线宽;光纤光栅法布里-珀罗(FBG F-P)腔;法拉第旋转器(FR) 中图分类号:TN253文献标识码:A文章编号:1005-0086(2007)07-0770-03 1550nm Hig h Efficient Narrow Lin ew id th Fib er Laser WU Bo**,LIU Yong-Zhi,LIU Shuang,ZH ANG Qian-shu,DAI Zh-i yong (School of Optoelectronic Information,University of Electronic Science and Technolog y,Chengdu610064,China) A bs tra ct:A high efficient narrow li newidth fiber laser based on fiber Bragg grating Fabry-Perot(FBG F-P)cavity was demonstrted.The spatial hole burning effect was restrained by fi ber Faraday rotator(FR).Two short FBG F-P cavities as narrow band width filters discrimi nated and selected the laser longitudi nal modes efficiently.Stable single frequency1550nm laser was acquired.Pumped by two976nm LD,the fiber laer exhi bi ted a11mW threshold.The73mW output power was obtai ned upon the maximu m145mW pump power.The opti ca-l optical efficciency was50%and the slope effi ci ency was 55%.T he3d B linewidth of laser was less than10kHz,measured b y the delayed sel-f heterod yne method with10km mono-mode fiber.T he high power narrow linewid th fi ber lasr can be used in high resolution fiber sensor system. Key words:laser technology;fiber laser narrow linewidth;fiber Bragg grating Fabry-Perot(FBG F-P)cavi ty;Fara-day rotator(FR) 1引言窄线宽光纤激光器作为光纤激光传感器光源,具有对电磁场的干扰、安全、体积小和可远程控制等特性[1,2]。目前,获得单纵模窄线宽光纤激光器有3种方案。1)通过控制腔内相遇光波的偏振状态来消除驻波效应引起的空间烧孔的非相干技术[3,4];2)在激光腔中加入未抽运掺杂光纤来选频,并抑制跳模的饱和吸收体[5~7];3)短腔光纤激光器,包括DFB光纤激光器和短腔DBR光纤激光器[8~10]。比较3种方案发现,方案1和方案2需要使用多个偏振控制器,且多为环形腔结构,控制难,转换效率低,输出功率极低;而方案3结构简单,输出功率超过200mW,斜率效率达24%,难点在于采用怎样的抽运方式在短增益光纤上实现高输出功率,以及怎样实现特殊封装。超短腔DBR结构光纤激光器国内也有研究,但是激光器效率低,输出功率最大仅为11mW,且线宽限制在MH z范围[11,12]。本文研制了一种采用双光纤光栅布里-珀罗(FBG F-P)腔选模的高掺Er3+线形腔窄线宽光纤激光器。该光纤激光器结合了非相干技术,输出功率高,能量转换效率高,线宽极窄,并具有结构简单、全光纤化和信噪比高等特点,可应用于高精度的光纤传感系统。 2窄线宽光纤激光器实验结果光纤激光器主要由2个FBG F-P腔和高掺Er3+光纤线形腔构成,实验装置如图1所示。激光器的增益介质为高掺Er3+光纤,长度为3m,在978nm波长处峰值吸收系数为17 dB/m,在1550nm波长处峰值吸收系数为30dB/m。实验中,采用了双向抽运方式,抽运光源为中心波长976nm的LD,LD 1与LD2的最大抽运功率分别为76mW和69mW。由于在线形腔结构中容易产生空间烧孔效应,引起多纵模振荡,所以光电子#激光第18卷第7期2007年7月Journal of Optoelectronics#Laser V ol.18N o.7Jul.2007 *收稿日期:2006-08-11修订日期:2006-11-07 *基金项目:国家自然科学基金资助项目(60377021) **E-m ail:w-bo@https://www.wendangku.net/doc/523661845.html,

华南理工大学 杨中民 窄线宽光纤激光器 2010