华南理工大学 杨中民 窄线宽光纤激光器 2011
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 µmS. H. Xu, Z. M. Yang, T. Liu, W. N. Zhang, Z. M. Feng, Q. Y. Zhang *,and Z. H. JiangInstitute of Optical Communication Materials, South China University of Technology, GuangZhou 510641, P. R. China* qyzhang@Abstract: An efficient single frequency fiber laser by using anewly-developed Er3+/Yb3+ co-doped single mode phosphate glass fiber withthe net gain coefficient of 5.2 dB/cm and propagation loss coefficient of 0.04dB/cm has been demonstrated. Over 300 mW stable continuous -wave singletransverse and longitudinal mode seed lasering at 1.5 µm has been achievedfrom a 2.0 cm-long active fiber. The measured slope efficiency and thecalculated quantum efficiency of laser emission are found to be 30.9% and0.938 ± 0.081, respectively. It is found that the linewidth of the fiber laser isless 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 AmericaOCIS codes: (140.3510) Lasers, fiber; (060.2280) Fiber design and fabrication; (060.2410)Fibers, erbiumReferences and links1. G. Bonfrate, F. Vaninetti, and F. Negrisolo, “Single-frequency MOPA Er3+ DBR fiber Laser for WDM digitaltelecommunication 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 domainreflectometry,” 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 fiberlasers,” 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 pulsesusing 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-fiberQ-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 fiberlaser 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, “Cooperativeupconversion 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 ahighly 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 ofsingle-mode Er3+/Yb3+ co-doped phosphate glass fibers,” 2nd IEEE International Nanoelectronics Conference 1–3, 633 (2008)13. Y. Hu, S. Jiang, T. Luo, K. Seneschal, M. Morrell, F. Smehtala, S. Honkanen, J. Lucas, and N. Peyghambarian,“Performance of high-concentration Er3+-Yb3+-codoped phosphate fiber amplifiers,” IEEE Photon. Technol. Lett.13(7), 657–659 (2001).#119310 - $15.00 USD Received 30 Oct 2009; revised 27 Dec 2009; accepted 30 Dec 2009; published 11 Jan 2010 (C) 2010 OSA18 January 2010 / Vol. 18, No. 2 / OPTICS EXPRESS 124914. C. Jacinto, S. L. Oliveira, T. Catundab, A. Andrade, J. Myers, and M. Myers, “Upconversion effect on fluorescencequantum 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,” IEEEJ. Quantum Electron. 33(10), 1699–1705 (1997).16. T. Liu, Z. M. Yang, and S. H. Xu, “3-Dimensional heat analysis in short-length Er3+/Yb3+ co-doped phosphate fiberlaser 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 at980 nm,” Opt. Lett. 14(18), 1002–1004 (1989).1. IntroductionSingle 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 designRE 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.#119310 - $15.00 USD Received 30 Oct 2009; revised 27 Dec 2009; accepted 30 Dec 2009; published 11 Jan 2010 (C) 2010 OSA18 January 2010 / Vol. 18, No. 2 / OPTICS EXPRESS 12501520153015401550156015700510152025G 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 ofa short piece of Er 3+/Yb 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 ofFig. 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 2010measured by an optical spectrum analyser (OSA, Anritsu MS9710C) and a power meter (PM, Ophir NovaII), respectively.3. Single-frequency fiber laser performanceFigure 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 transientfluctuations 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]:(C) 2010 OSA 18 January 2010 / Vol. 18, No. 2 / OPTICS EXPRESS 1252#119310 - $15.00 USD Received 30 Oct 2009; revised 27 Dec 2009; accepted 30 Dec 2009; published 11 Jan 20101/p s s ah P T h P νϕν= 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 ofthe fiber laser was measured by the self-homodyne method using a 48.8-km-fiber delay. Figure 5 shows the homodyne signalR 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 laserlinewidth 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 2010spectrum analyzer. The fall at low frequencies below 2 kHz is caused by the low-frequency filter in the photoreceiver. 0100200300400500-160-140-120-100-80-60R 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. ConclusionsIn 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.AcknowledgementThe authors would like to acknowledge support from the NSFC (Grant Nos. U0934001 and 60977060).(C) 2010 OSA 18 January 2010 / Vol. 18, No. 2 / OPTICS EXPRESS 1254#119310 - $15.00 USD Received 30 Oct 2009; revised 27 Dec 2009; accepted 30 Dec 2009; published 11 Jan 2010。
FM Photonics推出国产窄线宽光纤激光器
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一种高功率窄线宽拉曼光纤激光器[发明专利]
![一种高功率窄线宽拉曼光纤激光器[发明专利]](https://img.taocdn.com/s3/m/5815ed334531b90d6c85ec3a87c24028915f8563.png)
专利名称：一种高功率窄线宽拉曼光纤激光器专利类型：发明专利
发明人：王振华,白航宇,崔索超,陈炯,王小兵申请号：CN202111448565.2
申请日：20211130
公开号：CN114336238A
公开日：
20220412
专利内容由知识产权出版社提供
摘要：本发明公开了一种高功率窄线宽拉曼光纤激光器，包括通过无源光纤顺序连接的DFB半导体激光器、第一光纤隔离器、第一光纤耦合器、第一波分复用器、第一单模光纤和第二单模光纤、第二波分复用器、第二光纤耦合器和用于保护光纤的光纤输出接头，第一单模光纤和第二单模光纤之间连接有第二光纤隔离器，第一光纤耦合器和第二光纤耦合器上还分别连接有第一光电探测器和第二光电探测器，第一波分复用器和第一单模光纤之间连接有1570nm泵浦激光器，第二单模光纤和第二波分复用器之间还连接有吸收盒；本发明采用多级窄线宽拉曼光纤放大，并对每一级放大进行优化，可以更好地抑制受激布里渊散射，提高激光器输出功率。
申请人：华中光电技术研究所(中国船舶重工集团公司第七一七研究所)
地址：430000 湖北省武汉市洪山区雄楚大街981号
国籍：CN
代理机构：武汉凌达知识产权事务所(特殊普通合伙)
代理人：刘念涛
更多信息请下载全文后查看。
光纤激光频率调谐与噪声抑制关键技术及应用.doc-华南理工大学
2018年度广东省科学技术奖公示表（自然科学奖、技术发明奖、科技进步奖格式）项目名称光纤激光频率调谐与噪声抑制关键技术及应用主要完成单位华南理工大学主要完成人（职称、完成单位、工作单位）1.徐善辉（教授、华南理工大学）主要贡献：本项目负责人，提出了主要的学术思想，制定了总体研究方案。
本项目美国发明专利1-2、发明专利3-5、7-9的第一、专利6的第二和实用新型专利的第一发明人；多篇论文的通信作者以及代表性专著的主要撰写人员。
2.杨中民（教授、华南理工大学）主要贡献：本项目的主要完成人之一，在单频光纤激光噪声机理与抑制以及可调谐等方面开展工作作，对“技术发明成果”中的第2-3点做出了突出贡献。
美国发明专利1的第三、美国专利2的第二、发明专利3、7、8的第二、专利4、5、9第三、专利6第四和实用新型专利的第二发明人。
多篇论文的通信作者以及代表性专著的主要撰写人员。
3.张勤远（教授、华南理工大学）主要贡献：本项目的主要完成人之一。
在单频光纤激光噪声机理方面开展工作，对“技术发明成果”中的第2点做出了突出贡献。
美国发明专利1的第五、发明专利3的第四、专利4-6、8-9第五发明人。
4.杨昌盛（高级工程师、华南理工大学）主要贡献：本项目的主要完成人之一。
在单频光纤激光谐振腔设计、可调谐器件与方案设计等方面开展工作，对“技术发明成果”中的第3点做出了突出贡献。
美国发明专利1的第二、美国发明专利2的第五、发明专利4-5、9的第二、专利6、8第三发明人。
5.冯洲明（工程师、华南理工大学）主要贡献：本项目的主要完成人之一。
在单频光纤激光谐振腔制作、模式控制以及系统集成等方面开展工作，对“技术发明成果”中的第1点做出了突出贡献。
美国发明专利1-2的第四、发明专利6的第一、专利4、5、7-9第四发明人。
6.姜中宏（教授、华南理工大学）主要贡献：本项目的主要完成人之一，本项目的技术指导。
在纤芯发光机理、光纤材料物理化学性质对模式稳定及噪声影响等开展工作，对“技术发明成果”中的第1-2点做出了突出贡献。
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400mW ultrashort cavity low-noise single-frequency Yb3 -doped phosphate fiber laserShanhui Xu,Zhongmin Yang,*Weinan Zhang,Xiaoming Wei,Qi Qian,Dongdan Chen,Qinyuan Zhang,Shaoxiong Shen,Mingying Peng,and Jianrong QiuState Key Laboratory of Luminescent Materials and Devices and Institute of OpticalCommunication Materials,South China University of Technology,Guangzhou510640,China*Corresponding author:yangzm@Received June23,2011;revised August22,2011;accepted August22,2011;posted August24,2011(Doc.ID149805);published September15,2011A compact,low-noise,single-frequency fiber laser by using a newly developed Yb3þheavily doped single-modephosphate glass fiber has been demonstrated.Over400mW stable continuous wave single transverse and longitu-dinal mode laser at1:06μm was achieved from a0:8cm long active fiber.The measured slope efficiency and esti-mated quantum efficiency of laser emission are72.7%and93%,respectively.The signal-to-noise ratio is higher than72dB,and the linewidth of the fiber laser is less than7kHz,while the measured relative intensity noise is less than−130dB=Hz at frequencies of over1:5MHz.©2011Optical Society of AmericaOCIS codes:140.3510,060.2280,140.3615.A single-frequency fiber laser at1:06μm has experienced intense research in the past few years for applications, such as laser interferometric gravitational-wave observa-tory,advanced remote sensing,coherent beam com-bining,kilowatt-class high power laser with a master oscillator power amplifier technique,and laser LIDAR [1–4].Especially in the application of multiple paths co-herent beam combining,a low-noise single-frequency la-ser with hundreds of milliwatt output power is required. Although optical amplifiers can boost the single-frequency output power,it is still preferable to obtain the hundreds milliwatt level,high signal-to-noise ratio la-ser directly from fiber oscillators.A short linear reso-nance cavity configuration,such as a 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[5–7].Y.Kaneda et al.have reported a DBR laser at1:06μm with>200mW output power in a Yb3þ-doped phosphate glass fiber for first time[8].A single-frequency laser with the linewidth of<3kHz has been achieved from a1:5cm length phosphate glass fiber.However,the effective length of the resonator is designed to be4–5cm,which easily leads to multi-longitude mode emissions and needs extremely strict temperature control for the cavity.To ensure the laser operating on the single longitude mode, further shortening the resonance cavity is required,but it would limit the laser output power.In order to increase the laser output power,a higher concentration of Yb3þions is necessary to be doped into the glass fiber core. However,higher Yb3þconcentration can easily cause the blue cooperative upconversion emission due to the ions-cluster effects and decrease the quantum efficiency of Yb3þat1:06μm.In addition,during laser operation a significant gradient heat distribution along the fiber length deteriorates the laser performance[9,10].In our previous works,a3D short-cavity heat flow management technique was proposed and an efficient 300mW low-noise single-frequency fiber laser at1:5μmwas achieved from a2cm long Er3þ=Yb3þ-codoped phos-phate glass fiber[10].In this paper,we report an over 400mW low-noise single-frequency fiber laser at 1:06μm from a1:4cm effective resonator cavity constructed by a0:8cm long Yb3þ-doped phosphate glass fiber.The Yb3þ-doped phosphate glass fiber was drawn using a fiber-drawing tower through a phosphate glass preform fabricated by the rod-in-tube technique[11]. More details of processing the glass preform can be found in our previous work on the Er3þ=Yb3þ-codoped phosphate glass fiber[12,13].15:2wt%Yb3þions were doped uniformly in the core region.The measured fluor-escence lifetime of a Yb3þion is1:84ms,which is higher than that of Yb3þion concentration at12:0wt%in other reports[14].The designed phosphate glass fiber has a core diameter of5:0μm with an NA of0.14at1:06μm. The cutoff wavelength was calculated to be900nm.The core-to-cladding offset is less than1:0μm.The propaga-tion loss at1300nm of the Yb3þ-doped phosphate glass fiber is lower than0:06dB=cm.A peak absorption coeffi-cient of the fiber core glass is10:7cm−1at976nm,and a net gain coefficient of the phosphate glass fiber was mea-sured to be5:7dB=cm.Such strong absorption coeffi-cient allows efficient absorption of the pump light within a few centimeters,and generates hundreds of milliwatts of output power without the need of an exter-nal optical amplifier.The laser cavity is composed of one narrowband fiber Bragg grating(NB-FBG)and one dielectric mirror,which is butt-coupled to the one end facet of a short piece of Yb3þ-doped phosphate fiber,as shown in Fig.1.The NB-FBG was irradiated with a3dB linewidth of0:05nm and a reflectivity of55.0%at1063:90nm,and it was fused splicing with the0:8cm long phosphate fiber.The reflec-tivity of the dielectric mirror is larger than99.0%at 1:06μm and smaller than2%at976nm.Two high-power 976nm FBG-stabilized pump laser diodes(976nm LD1 and976nm LD2)with orthogonal polarization output were combined through a polarization beam combiner. The pump lasers were coupled into the laser cavity through a980=1064nm WDM,and the emission spectrum and the optical power of fiber laser were measured by an optical spectrum analyzer(OSA)and a power meter, respectively.3708OPTICS LETTERS/Vol.36,No.18/September15,20110146-9592/11/183708-03$15.00/0©2011Optical Society of AmericaAs shown in Fig.1,the effective length of the resonator includes the 0:8cm active fiber and a half of the 1:0cm NB-FBG.It is only less than 1:4cm,giving a longitudinal mode spacing of 7:4GHz.The NB-FBG has a reflection bandwidth of less than 13:3GHz.It is clear that only one longitudinal mode is supported within the laser cav-ity.Figure 2(a)illustrates the output spectrum of the Yb 3þ-doped phosphate fiber laser.The fiber laser spec-trum centered at 1063:90nm is recorded with a spectrum resolution of 0:1nm by OSA.The signal-to-noise ratio (SNR)of more than 72dB is obtained.The laser cavity was assembled into a copper tube,which was tempera-ture-controlled by a cooling system with a resolution of 0:05°C.The single-frequency characteristics were con-firmed by the scanning Fabry –Perot interferometer (SA210-9A),as shown in Fig.2(b).With the proper tem-perature control,the laser operated stably in a single fre-quency without mode hop and mode competition.As shown in Fig.2(c),the output power of the Yb 3þ-doped phosphate fiber laser at 1:06μm versus the launched pump power.The lasing threshold is around 25mW.When the pump power is above the threshold,the laser output power is approximately linearly increased with the pump power.An output power of 408mW is obtained from the 0:8cmYb 3þ-doped phosphate fiber at the pumppower of 570mW,which is the highest output power from this kind of fiber lasers reported to date [8,15–17].The slope efficiency against the launched pump power is measured to be 72.7%,and the experimental quantum ef-ficiency of the laser emission related to the absorbed pump power is estimated to be 93%,since only 85%of the pump power was coupled into the phosphate fiber core due to the coupling loss,scattering,and pump leak-age.From our understanding,these are also the highest slope efficiency and quantum efficiency from this kind of single-frequency fiber laser [8,15–17].The stabilities of the output power at 300mW in an hour were investigated and the result is shown in Fig.2(d).The power instability of <0:25%of the average power was observed,which is caused by the small fluctuations in the pump laser power and the small changes of ambient temperature.After the fiber laser worked for half an hour,the output power of the laser obviously became very stable.As shown in Fig.2(c),the output power was saturated at the pump power larger than 570mW.When the pump power was set to be more than 740mW,the output power of the laser became unstable due to the backscatter light inducing the instability of the two pump LDs.Laser noise is an important parameter of the single-frequency fiber laser.The relative intensity noise (RIN)was measured using bandwidth resolution 3:1kHz of the electrical spectrum and the results are shown in Fig.3.As shown by the left inset of Fig.3,at the low frequencies of <230kHz there are noise peaks at −100dB =Hz,due to environmental influences,such as acoustics or vibration.With increasing the frequency to 500kHz,the RIN de-creases from −100dB =Hz to −120dB =Hz.A relaxation os-cillation frequency peak of −112dB =Hz was observed at the frequencies of 970kHz.The RIN is stabilized less than −130dB =Hz for frequencies above 1:5MHz.In order to further investigate the phase noise charac-teristics of the fiber laser,the linewidth of the fiber laser was measured by a self-heterodyne method using a 10km fiber delay.It is 60kHz with −20dB from the peak,which indicates the measured laser linewidth is approximately 3:0kHz FWHM,as shown in the right inset of Fig.3.The linewidth resolution of the self-heterodyne measurement with a 10km fiber delay is about 6:6kHz,so the laser line-width is affirmed to be less than 7kHz.In conclusion,an over 400mW single longitude mode laser at 1:06μm from a 0:8cm long Yb 3þ-dopedDielectric Mirror0.8-cm Yb 3+-doped Phosphate FiberNB-FBGLaser Output980/1060nm WDM976 nm LD11060nm Isolator976 nm LD2PBCFig.1.(Color online)Experimental setup of the short linear cavity Yb 3þ-doped phosphate fiber laser.P o w e r L e v e l (d B m )Wavelength (nm)P Z T V o l t a g e (V )Time (s)L a s e r O u t p u t P o w e r (m W )Pump Power (mW)280290300310P o w e r (m W )Time (min)< 0.25 %(d)Fig.2.(Color online)(a)Laser spectrum of the Yb 3þ-doped phosphate fiber laser.(b)The longitudinal modes characteris-tics of the fiber laser measured by the scanning Fabry –Perot interferometer.(c)The output power of the fiber laser at 1064nm versus the pump power.(d)The power stabilities of the fiber laser for anhour.Fig.3.(Color online)Noise characteristics of the Yb 3þ-doped phosphate fiber laser.Inset (left):the magnified RIN at the low frequencies of <2:0MHz.Inset (right):the self-heterodyne line-width of the fiber laser.September 15,2011/Vol.36,No.18/OPTICS LETTERS3709phosphate fiber has been demonstrated.The slope effi-ciency is72.7%and the quantum efficiency of laser emis-sion has been estimated to be93%.The SNR is morethan72dB,and the RIN of the fiber laser is less than −130dB=Hz at the frequency higher than1:5MHz.The laser linewidth is less than7kHz.These results show thatthe short linear cavity based on the Yb3þ-doped phos-phate single-mode glass fiber is a very promising candi-date as an efficient and compact single-frequency fiber laser at1:0μm region.This research was supported by the China State863Hi-tech Program(2011AA030203),the National NaturalScience Foundation of China(NSFC)(U0934001and60977060),the Guangdong Province and Hong Kong In-vite Public Bidding Program(TC10BH07-1),the Scienceand Technology Project of Guangdong(2009A090100044,2009B091300127,cgzhzd0903,and2010B2101230),theProject of Education Department of Guangdong Province(2009N9100200),the Fundamental Research Funds forthe Central Universities(2009ZM0219,2011ZZ0001,and2009ZZ0054),the Open Research Fund of State Key La-boratory of Precision Spectroscopy,and the Young Nat-ural Science Foundation of South China University ofTechnology(E5090880).References1.LIGO Scientific Collaboration,Rep.Prog.Phys.72,076901(2009).2.D.Psaltis,Science298,1359(2002).3.Y.Ma,X.Wang,J.Leng,H.Xiao,X.Dong,J.Zhu,W.Du,P.Zhou,X.Xu,L.Si,Z.Liu,and Y.Zhao,Opt.Lett.36, 951(2011).4.J.G.Williams,S.G.Turyshev,and D.H.Boggs,Phys.Rev.Lett.93,261101(2004).5.M.Leigh,W.Shi,J.Zong,Z.Yao,S.Jiang,and N.Peyghambarian,Appl.Phys.Lett.92,181108(2008).6.T.Qiu,S.Suzuki, A.Schlzgen,L.Li, A.Polynkin,V.Temyanko,J.V.Moloney,and N.Peyghambarian,Opt.Lett.30,2748(2005).7.M.Leigh,W.Shi,J.Zong,J.Wang,S.Jiang,and N.Peyghambarian,Opt.Lett.32,897(2007).8.Y.Kaneda,C.Spiegelberg,J.Geng,Y.Hu,T.Luo,J.Wang,S.Jiang,Proceeding of IEEE Conference on Lasers and Electro-Optics(IEEE,2004),paper CThO3.9.T.Liu,Z.M.Yang,and S.H.Xu,Opt.Express17,235(2009).10.S.H.Xu,Z.M.Yang,T.Liu,W.N.Zhang,Z.M.Feng,Q.Y.Zhang,and Z.H.Jiang,Opt.Express18,1249(2010).11.Q.Qian and Z.M.Yang,Acta Opt.Sin.30,1904(2010).12.S.H.Xu,Z.M.Yang,Q.Y.Zhang,Z.D.Deng,and Z.H.Jiang,Chin.Phys.Lett.23,633(2006).13.S.H.Xu,Z.M.Yang,Z.M.Feng,Q.Y.Zhang,Z.H.Jiang,andW.C.Xu,Chin.Phys.Lett.26,047806(2009).14.Y.W.Lee,M.J.F.Digonnet,S.Sinha,K.E.Urbanek,R.L.Ryer,and S.Jiang,IEEE J.Sel.Top.Quantum Electron.15, 93(2009).15.S.Huang,Y.Feng,G.Qin,A.Shirakawa,M.Musha,andK.Ueda,Jpn.J.Appl.Phys.43,L1379(2004).16.W.Guan and J.R.Marciante,Electron.Lett.43,558(2007).17.J.L.Chen,L.Wang,L.P.Chang,G.Y.Li,B.Chen,and Z.Q.Lin,Chinese Science Bulletin53,2729(2008).3710OPTICS LETTERS/Vol.36,No.18/September15,2011。