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Low-threshold wavelength-switchable photonic crystal fiber laser based on superimposed fiber Bragg gratings
Optical Fiber Technology 50 (2019) 19–22
Contents lists available at ScienceDirect
Optical Fiber Technology journal homepage: www.elsevier.com/locate/yofte
Low-threshold wavelength-switchable photonic crystal fiber laser based on superimposed fiber Bragg gratings Peng Jianga,b, Qiang Xua,b, Yuyu Zhua, Yani Zhangb,c,
T
⁎
a
School of Physics and Optoelectronics Technology, Baoji University of Arts & Science, Baoji 721016, China Baoji Engineering Technology Research Center on Ultrafast Laser and New Materials, Baoji 721016, China c School of Arts and Sciences, Shaanxi University of Science & Technology, Xi’an 710021, China b
A R T I C LE I N FO
A B S T R A C T
Keywords: Fiber laser Photonic crystal fiber Superimposed fiber Bragg gratings Germanium doped fiber Wavelength-switchable
We report a wavelength-switchable photonic crystal fiber laser based on superimposed fiber Bragg gratings with a low threshold. Quadruple superimposed fiber Bragg gratings are fabricated in a photosensitive PCF and inserted between small core erbium-doped PCF and step-index fiber, which reduce the intracavity loss below 2 dB. Four wavelength switching stable outputs are obtained, and the lowest threshold power is only ∼0.85 mW with a slope efficiency of ∼13.3% correspondingly.
1. Introduction The development of photonic crystal fibers (PCFs) technology during recent years is expected to greatly improve the performance of fiber lasers [1–3]. For rare-earth doped fibers, PCFs technology can provide better control of modal properties and the overlap between pump, signal-mode, and rare-earth dopant than conventional fibers by appropriate design of the holey cladding [4,5]. This provides the opportunity allows rare-earth doped PCF lasers operated at very low pump threshold and high slope-efficiency [6]. Fiber Bragg gratings (FBGs) have been widely used in sensing and communication fields [7,8], and in laser systems, FBGs play a substantial role in high quality laser cavities and enabling practical utilization of all-fiber lasers. However, rare-earth doped PCFs are usually lack of enough photosensitivity to write FBGs because doping germanium and rare earth simultaneously is difficult [9] and harmful to the energy transfer efficiencies of rare-earth [10]. Furthermore, the mode mismatch of PCF and conventional step index optical fiber often lead to large insertion losses [11,12]. In this paper, a high photosensitivity germanium-doped PCF is used as intermediary fiber between small core erbium-doped PCF and stepindex fiber. Some advantages are brought from this: first, utilizing its potent photosensitivity, it is easy to prepare all sorts of grating devices, such as superimposed fiber Bragg gratings in this work; second, the use of intermediary fibers with a high numerical aperture can effectively reduce the loss caused by mode mismatch between small core erbiumdoped PCF and step-index fiber [13,14]. Quadruple superimposed FBGs
⁎
are fabricated in the photosensitive PCF. Based on that, a four wavelength switchable photonic crystal fiber laser is experimentally demonstrated. The lasing wavelengths can be easily switched through controlling grating’s wavelength by a piezoelectric actuator, which show a significant improvement in output power stability or switching time compared with the conventional method of adjusting the polarization in the cavity [15–17]. With small care erbium-doped PCF and low-loss splicing, the lowest threshold power is only ∼0.85 mW with a slope efficiency of ∼13.3%. 2. Photosensitive PCF and superimposed FBG fabrication The homemade photosensitive photonic crystal fiber is drawn from a microstructured preform with a high germanium doped core. The high germanium doped core region is fabricated by modified chemical vapor deposition (MCVD) within a silica preform, and the maximum concentration in the core center was 36 mol%. Five rings of capillaries and an external jacket tube are stacked together around the germanium doped rod to form the microstructured preform. And the microstructured preform is finally drawn down to the diameter of 125 μm with the germanium doped core region of ∼5.5 μm (see in Fig. 1). The hole diameter d and pitch Λ in the final fiber were measured to be 3.4 μm and 5.6 μm, respectively, corresponding to d/Λ ∼ 0.6. The photosensitive PCF are H2-loaded (H2 pressure 12 atm) at 80 °C for 1 weeks to further enhance its photosensitivity. For the sake of reducing hydrogen outgassing and transverse scattering of UV exposure laser by the air hole structure, we fill index matching liquid in the PCF’s
Corresponding author. E-mail address: [email protected] (Y. Zhang).
https://doi.org/10.1016/j.yofte.2019.01.028 Received 11 November 2018; Received in revised form 21 December 2018; Accepted 23 January 2019 1068-5200/ © 2019 Elsevier Inc. All rights reserved.
Optical Fiber Technology 50 (2019) 19–22
P. Jiang, et al.
energy of high order-modes distributes in cladding region and can hardly couple into single mode fiber. Superimpose FBGs (SFBGs) are fabricated by overwriting grating in the photosensitive fiber. The fibers are precisely drawn during grating inscribing to vary the resonant wavelength under one phase mask. A good linear relationship between tension forces and wavelength shift with a ratio of 0.0168 nm/N is obtained and the wavelength modulation can reach more than 8 nm through this way. Fig. 3 shows the transmission spectra of superimpose FBGs used for our laser cavity. Both of the superimposed gratings are ∼20 mm long and composed of four FBGs. The strength for the input grating is ∼15 dB with wavelength spacing of ∼1.6 nm (centered at 1544.98 nm, 1546.58 nm, 1548.17 nm and 1549.74 nm respectively). For the output grating, the strength is ∼9 dB and the wavelength spacing is ∼1.4 nm (centered at 1544.57 nm, 1545.96 nm, 1547.37 nm and 1548.71 nm respectively). 3. The wavelength-switchable photonic crystal fiber laser The experimental setup for wavelength-switchable laser is shown in Fig. 4. The set-up is pumped by light from a diode laser operating at 976 nm through a wavelength division multiplexer (WDM). A piece of small core erbium doped PCF (made by FiberHome with absorption of 12.2 dB/m at 1550 nm) is spliced inbetween those two superimpose FBGs mentioned above to create the resonant cavity with a total length of ∼150 cm. The inset in Fig. 4 gives a microscope image of the erbium doped fiber with an outer diameter of 125 μm, a pitch Λ = 4 μm, an hole diameter d = 2 μm, and a doped core diameter of ∼4 μm. In our laser configuration, the photosensitive PCF as intermediary fiber has been effectively reduce the mode mismatch between small core erbiumdoped PCF and step-index fiber, which reduce the intracavity loss below 2 dB. The low R superimposed FBG is stretched by a piezoelectric actuator (PZS001 by Thorlabs) for precise control of its wavelengths. Meanwhile, the high R superimposed FBG is glued onto a passive gauge to minimize its wavelength variations responding to temperature-related effects. By stretching the low R superimposed FBG, a wavelength shift is produced to permits one wavelength matching between two superimposed FBGs, which realizes the switching among four emitted wavelengths one by one. The laser output spectra are measured by an optical spectrum analyzer (OSA) with 0.02 nm resolution. Fig. 5 shows wavelengthswitching output spectra under 10 mW pump power. Fix the pump power at 10 mW, the variations of output powers and peak wavelengths are measured every 3 min for 10 times at 25 °C. The results at 1545.36 nm are exhibited in Fig. 6, the power and wavelength fluctuations were 0.6 dB and 0.02 nm respectively. The other wavelength results are similar, much better than measurements in ring configurations or another short cavity lasers [18,19]. Thus, the experimental results demonstrated the laser configuration has a favorable stability.
Fig. 1. Optical microscope image of photosensitive PCF.
Fig. 2. Spectra of superimposed PCF Bragg grating.
air holes and seal the PCF endfaces by splicing both ends to step-index fibers. Fiber grating are written using an ArF-Excimer laser (Compex COMPexPro) at the wavelength of 193 nm and an optical phase with the pitch of 1077.74 nm. The exposure energy density is about 280 mJ/ cm2. The spectra of Bragg grating inscribed in the photosensitive PCF are presented in Fig. 2. Note that some resonances peaks corresponding to high-order mode resonances are also observed at shorter wavelength in the transmission spectrum. They find no reflection peaks because the
Fig. 3. Transmission spectra of superimpose FBGs inscribed within PCF for (a) input grating and (b) output grating. 20
Optical Fiber Technology 50 (2019) 19–22
P. Jiang, et al.
Fig. 4. Schematic configuration of the wavelength-switchable PCF laser.
Fig. 5. Output spectra of the laser at single-wavelength operation 1545.36, 1545.96, 1548.55 and 1550.12 nm, respectively.
Fig. 7. Laser output power with the variation of pump power at the different wavelengths operation.
Fig. 7 shows the slope efficiency of laser output power with the variation of pump power at the different operating wavelengths. The slope efficiencies are about 13.3%, 12.0% and 11.5% and 8.9% for the operating wavelengths of 1545.36, 1545.96, 1548.55 and 1550.12 nm, respectively. By monitoring the laser output spectra corresponding to the pumping, the laser pump threshold is confirmed of about 0.85, 0.97, 1.1 and 1.5 mW, respectively. The different performances for the four operating wavelengths are mainly cause by the reflectivity nonuniformity of superimposed FBGs.
is used for superimposed Bragg gratings fabrication and inserted between small core erbium-doped PCF and step-index fiber. As intermediary fiber, it effectively reduces the loss caused by mode mismatch. Four wavelength switching stable outputs are obtained with a low pump threshold of ∼0.85 mW and a slope efficiency of ∼13%.
Acknowledgements This work was supported by National Natural Science Foundation of China (Nos. 11547247); International Science & Technology Cooperation and Exchanges Project of Shaanxi (No. 2018KW-16); Scientific Research Program Funded by Shaanxi Provincial Education Department (No. 18JK0042).
4. Conclusion In this paper, a wavelength-switchable photonic crystal fiber laser based on superimposed fiber Bragg gratings is proposed and experimentally demonstrated. A high photosensitivity germanium-doped PCF
Fig. 6. (a) Power and (b) wavelength fluctuation at 1545.36 nm during 30 min. 21
Optical Fiber Technology 50 (2019) 19–22
P. Jiang, et al.
References
[10] P. Myslinski, D. Nguyen, J. Chrostowski, Effects of concentration on the performance of erbium-doped fiber amplifiers, J. Lightwave Technol. 15 (1) (1997) 112–120. [11] L. Xiao, M.S. Demokan, W. Jin, et al., Fusion splicing photonic crystal fibers and conventional single-mode fibers: microhole collapse effect, J. Lightwave Technol. 25 (11) (2007) 3563–3574. [12] Z. Xu, K. Duan, Z. Liu, et al., Numerical analyses of splice losses of photonic crystal fibers, Opt. Commun. 282 (23) (2009) 4527–4531. [13] A.D. Yablon, R. Bise, Low-loss high-strength microstructured fiber fusion splices using grin fiber lenses, IEEE Photonic. Technol. Lett. 17 (1) (2004) 118–120. [14] F.E. Seraji, S. Farsinezhad, To Optimize splice joint between different PCF-based devices and SMF transmission medium, Chin. Opt. Lett. 7 (3) (2009) 246–250. [15] X.M. Liu, Y. Chung, A. Lin, et al., Tunable and switchable multi-wavelength erbiumdoped fiber laser with highly nonlinear photonic crystal fiber and polarization controllers, Laser Phys. Lett. 5 (12) (2010) 904–907. [16] Z.Y. Liu, Y.G. Liu, J.B. Du, et al., Tunable multiwavelength erbium-doped fiber laser with a polarization-maintaining photonic crystal fiber sagnac loop filter, Laser Phys. Lett. 5 (6) (2010) 446–448. [17] R.A. Perez-herrera, M. Fernandez-vallejo, S. Diaz, et al., Stability comparison of two quadruple-wavelength switchable erbium-doped fiber lasers, Opt. Fiber Technol. 16 (4) (2010) 205–211. [18] M.A. Quintela, R.A. Perez-Herrera, et al., Stabilization of dual-wavelength erbium doped ring fiber lasers by single-mode operation, IEEE Photon. Technol. Lett. 22 (6) (2010) 368–370. [19] R.A. Perez-Herrera, S. Chen, et al., Stability performance of short cavity Er-doped fiber lasers, Opt. Commun. 283 (6) (2010) 1067–1070.
[1] K. Mondal, P.R. Chaudhuri, Designing high performance Er+3-doped fiber amplifier in triangular-lattice photonic crystal fiber host towards higher gain, low splice loss, Opt. Laser Technol. 43 (8) (2011) 1436–1441. [2] K. Mondal, P.R. Chaudhuri, Investigation of structural dependence of host erbiumdoped triangular-lattice PCF on lasing properties and design of high performance laser, J. Mod. Optic. 60 (15) (2013) 1247–1252. [3] P. Yan, R. Lin, H. Chen, et al., Topological insulator solution filled in photonic crystal fiber for passive mode-locked fiber Laser, IEEE Photonic. Technol. Lett. 27 (3) (2015) 264–267. [4] J.A. Sánchez-martín, M.A. Rebolledo, J.M. Álvarez, et al., Erbium-doped photonic crystal fiber lasers optimization by microstructure control: experimental study analysis, Appl. Phys. B: Laser Opt. 110 (4) (2013) 579–584. [5] S. Hilaire, D. Pagnoux, P. Roy, et al., Numerical study of single mode Er-doped microstructured fibers: influence of geometrical parameters on amplifier performances, Opt. Express 14 (22) (2006) 10787–10865. [6] K. Furusawa, T. Kogure, J.K. Sahu, et al., Efficient low-threshold lasers based on an erbium-doped holey fiber, IEEE Photonic. Technol. Lett. 17 (1) (2005) 25–27. [7] Y. Zhang, B. Lin, S.C. Tjin, et al., Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating, Opt. Express 18 (25) (2010) 26345–26350. [8] N.F. Naim, A. Bakar, et al., Fault identification and localization for ethernet passive optical network using L-band ASE source and various types of fiber Bragg grating, Opt. Fiber Technol. 40 (2018) 159–164. [9] P. Laporta, S. Taccheo, S. Longhi, et al., Erbium-ytterbium microlasers: optical properties and lasing characteristics, Opt. Mater. 11 (2) (1999) 269–288.
22
Contents lists available at ScienceDirect
Optical Fiber Technology journal homepage: www.elsevier.com/locate/yofte
Low-threshold wavelength-switchable photonic crystal fiber laser based on superimposed fiber Bragg gratings Peng Jianga,b, Qiang Xua,b, Yuyu Zhua, Yani Zhangb,c,
T
⁎
a
School of Physics and Optoelectronics Technology, Baoji University of Arts & Science, Baoji 721016, China Baoji Engineering Technology Research Center on Ultrafast Laser and New Materials, Baoji 721016, China c School of Arts and Sciences, Shaanxi University of Science & Technology, Xi’an 710021, China b
A R T I C LE I N FO
A B S T R A C T
Keywords: Fiber laser Photonic crystal fiber Superimposed fiber Bragg gratings Germanium doped fiber Wavelength-switchable
We report a wavelength-switchable photonic crystal fiber laser based on superimposed fiber Bragg gratings with a low threshold. Quadruple superimposed fiber Bragg gratings are fabricated in a photosensitive PCF and inserted between small core erbium-doped PCF and step-index fiber, which reduce the intracavity loss below 2 dB. Four wavelength switching stable outputs are obtained, and the lowest threshold power is only ∼0.85 mW with a slope efficiency of ∼13.3% correspondingly.
1. Introduction The development of photonic crystal fibers (PCFs) technology during recent years is expected to greatly improve the performance of fiber lasers [1–3]. For rare-earth doped fibers, PCFs technology can provide better control of modal properties and the overlap between pump, signal-mode, and rare-earth dopant than conventional fibers by appropriate design of the holey cladding [4,5]. This provides the opportunity allows rare-earth doped PCF lasers operated at very low pump threshold and high slope-efficiency [6]. Fiber Bragg gratings (FBGs) have been widely used in sensing and communication fields [7,8], and in laser systems, FBGs play a substantial role in high quality laser cavities and enabling practical utilization of all-fiber lasers. However, rare-earth doped PCFs are usually lack of enough photosensitivity to write FBGs because doping germanium and rare earth simultaneously is difficult [9] and harmful to the energy transfer efficiencies of rare-earth [10]. Furthermore, the mode mismatch of PCF and conventional step index optical fiber often lead to large insertion losses [11,12]. In this paper, a high photosensitivity germanium-doped PCF is used as intermediary fiber between small core erbium-doped PCF and stepindex fiber. Some advantages are brought from this: first, utilizing its potent photosensitivity, it is easy to prepare all sorts of grating devices, such as superimposed fiber Bragg gratings in this work; second, the use of intermediary fibers with a high numerical aperture can effectively reduce the loss caused by mode mismatch between small core erbiumdoped PCF and step-index fiber [13,14]. Quadruple superimposed FBGs
⁎
are fabricated in the photosensitive PCF. Based on that, a four wavelength switchable photonic crystal fiber laser is experimentally demonstrated. The lasing wavelengths can be easily switched through controlling grating’s wavelength by a piezoelectric actuator, which show a significant improvement in output power stability or switching time compared with the conventional method of adjusting the polarization in the cavity [15–17]. With small care erbium-doped PCF and low-loss splicing, the lowest threshold power is only ∼0.85 mW with a slope efficiency of ∼13.3%. 2. Photosensitive PCF and superimposed FBG fabrication The homemade photosensitive photonic crystal fiber is drawn from a microstructured preform with a high germanium doped core. The high germanium doped core region is fabricated by modified chemical vapor deposition (MCVD) within a silica preform, and the maximum concentration in the core center was 36 mol%. Five rings of capillaries and an external jacket tube are stacked together around the germanium doped rod to form the microstructured preform. And the microstructured preform is finally drawn down to the diameter of 125 μm with the germanium doped core region of ∼5.5 μm (see in Fig. 1). The hole diameter d and pitch Λ in the final fiber were measured to be 3.4 μm and 5.6 μm, respectively, corresponding to d/Λ ∼ 0.6. The photosensitive PCF are H2-loaded (H2 pressure 12 atm) at 80 °C for 1 weeks to further enhance its photosensitivity. For the sake of reducing hydrogen outgassing and transverse scattering of UV exposure laser by the air hole structure, we fill index matching liquid in the PCF’s
Corresponding author. E-mail address: [email protected] (Y. Zhang).
https://doi.org/10.1016/j.yofte.2019.01.028 Received 11 November 2018; Received in revised form 21 December 2018; Accepted 23 January 2019 1068-5200/ © 2019 Elsevier Inc. All rights reserved.
Optical Fiber Technology 50 (2019) 19–22
P. Jiang, et al.
energy of high order-modes distributes in cladding region and can hardly couple into single mode fiber. Superimpose FBGs (SFBGs) are fabricated by overwriting grating in the photosensitive fiber. The fibers are precisely drawn during grating inscribing to vary the resonant wavelength under one phase mask. A good linear relationship between tension forces and wavelength shift with a ratio of 0.0168 nm/N is obtained and the wavelength modulation can reach more than 8 nm through this way. Fig. 3 shows the transmission spectra of superimpose FBGs used for our laser cavity. Both of the superimposed gratings are ∼20 mm long and composed of four FBGs. The strength for the input grating is ∼15 dB with wavelength spacing of ∼1.6 nm (centered at 1544.98 nm, 1546.58 nm, 1548.17 nm and 1549.74 nm respectively). For the output grating, the strength is ∼9 dB and the wavelength spacing is ∼1.4 nm (centered at 1544.57 nm, 1545.96 nm, 1547.37 nm and 1548.71 nm respectively). 3. The wavelength-switchable photonic crystal fiber laser The experimental setup for wavelength-switchable laser is shown in Fig. 4. The set-up is pumped by light from a diode laser operating at 976 nm through a wavelength division multiplexer (WDM). A piece of small core erbium doped PCF (made by FiberHome with absorption of 12.2 dB/m at 1550 nm) is spliced inbetween those two superimpose FBGs mentioned above to create the resonant cavity with a total length of ∼150 cm. The inset in Fig. 4 gives a microscope image of the erbium doped fiber with an outer diameter of 125 μm, a pitch Λ = 4 μm, an hole diameter d = 2 μm, and a doped core diameter of ∼4 μm. In our laser configuration, the photosensitive PCF as intermediary fiber has been effectively reduce the mode mismatch between small core erbiumdoped PCF and step-index fiber, which reduce the intracavity loss below 2 dB. The low R superimposed FBG is stretched by a piezoelectric actuator (PZS001 by Thorlabs) for precise control of its wavelengths. Meanwhile, the high R superimposed FBG is glued onto a passive gauge to minimize its wavelength variations responding to temperature-related effects. By stretching the low R superimposed FBG, a wavelength shift is produced to permits one wavelength matching between two superimposed FBGs, which realizes the switching among four emitted wavelengths one by one. The laser output spectra are measured by an optical spectrum analyzer (OSA) with 0.02 nm resolution. Fig. 5 shows wavelengthswitching output spectra under 10 mW pump power. Fix the pump power at 10 mW, the variations of output powers and peak wavelengths are measured every 3 min for 10 times at 25 °C. The results at 1545.36 nm are exhibited in Fig. 6, the power and wavelength fluctuations were 0.6 dB and 0.02 nm respectively. The other wavelength results are similar, much better than measurements in ring configurations or another short cavity lasers [18,19]. Thus, the experimental results demonstrated the laser configuration has a favorable stability.
Fig. 1. Optical microscope image of photosensitive PCF.
Fig. 2. Spectra of superimposed PCF Bragg grating.
air holes and seal the PCF endfaces by splicing both ends to step-index fibers. Fiber grating are written using an ArF-Excimer laser (Compex COMPexPro) at the wavelength of 193 nm and an optical phase with the pitch of 1077.74 nm. The exposure energy density is about 280 mJ/ cm2. The spectra of Bragg grating inscribed in the photosensitive PCF are presented in Fig. 2. Note that some resonances peaks corresponding to high-order mode resonances are also observed at shorter wavelength in the transmission spectrum. They find no reflection peaks because the
Fig. 3. Transmission spectra of superimpose FBGs inscribed within PCF for (a) input grating and (b) output grating. 20
Optical Fiber Technology 50 (2019) 19–22
P. Jiang, et al.
Fig. 4. Schematic configuration of the wavelength-switchable PCF laser.
Fig. 5. Output spectra of the laser at single-wavelength operation 1545.36, 1545.96, 1548.55 and 1550.12 nm, respectively.
Fig. 7. Laser output power with the variation of pump power at the different wavelengths operation.
Fig. 7 shows the slope efficiency of laser output power with the variation of pump power at the different operating wavelengths. The slope efficiencies are about 13.3%, 12.0% and 11.5% and 8.9% for the operating wavelengths of 1545.36, 1545.96, 1548.55 and 1550.12 nm, respectively. By monitoring the laser output spectra corresponding to the pumping, the laser pump threshold is confirmed of about 0.85, 0.97, 1.1 and 1.5 mW, respectively. The different performances for the four operating wavelengths are mainly cause by the reflectivity nonuniformity of superimposed FBGs.
is used for superimposed Bragg gratings fabrication and inserted between small core erbium-doped PCF and step-index fiber. As intermediary fiber, it effectively reduces the loss caused by mode mismatch. Four wavelength switching stable outputs are obtained with a low pump threshold of ∼0.85 mW and a slope efficiency of ∼13%.
Acknowledgements This work was supported by National Natural Science Foundation of China (Nos. 11547247); International Science & Technology Cooperation and Exchanges Project of Shaanxi (No. 2018KW-16); Scientific Research Program Funded by Shaanxi Provincial Education Department (No. 18JK0042).
4. Conclusion In this paper, a wavelength-switchable photonic crystal fiber laser based on superimposed fiber Bragg gratings is proposed and experimentally demonstrated. A high photosensitivity germanium-doped PCF
Fig. 6. (a) Power and (b) wavelength fluctuation at 1545.36 nm during 30 min. 21
Optical Fiber Technology 50 (2019) 19–22
P. Jiang, et al.
References
[10] P. Myslinski, D. Nguyen, J. Chrostowski, Effects of concentration on the performance of erbium-doped fiber amplifiers, J. Lightwave Technol. 15 (1) (1997) 112–120. [11] L. Xiao, M.S. Demokan, W. Jin, et al., Fusion splicing photonic crystal fibers and conventional single-mode fibers: microhole collapse effect, J. Lightwave Technol. 25 (11) (2007) 3563–3574. [12] Z. Xu, K. Duan, Z. Liu, et al., Numerical analyses of splice losses of photonic crystal fibers, Opt. Commun. 282 (23) (2009) 4527–4531. [13] A.D. Yablon, R. Bise, Low-loss high-strength microstructured fiber fusion splices using grin fiber lenses, IEEE Photonic. Technol. Lett. 17 (1) (2004) 118–120. [14] F.E. Seraji, S. Farsinezhad, To Optimize splice joint between different PCF-based devices and SMF transmission medium, Chin. Opt. Lett. 7 (3) (2009) 246–250. [15] X.M. Liu, Y. Chung, A. Lin, et al., Tunable and switchable multi-wavelength erbiumdoped fiber laser with highly nonlinear photonic crystal fiber and polarization controllers, Laser Phys. Lett. 5 (12) (2010) 904–907. [16] Z.Y. Liu, Y.G. Liu, J.B. Du, et al., Tunable multiwavelength erbium-doped fiber laser with a polarization-maintaining photonic crystal fiber sagnac loop filter, Laser Phys. Lett. 5 (6) (2010) 446–448. [17] R.A. Perez-herrera, M. Fernandez-vallejo, S. Diaz, et al., Stability comparison of two quadruple-wavelength switchable erbium-doped fiber lasers, Opt. Fiber Technol. 16 (4) (2010) 205–211. [18] M.A. Quintela, R.A. Perez-Herrera, et al., Stabilization of dual-wavelength erbium doped ring fiber lasers by single-mode operation, IEEE Photon. Technol. Lett. 22 (6) (2010) 368–370. [19] R.A. Perez-Herrera, S. Chen, et al., Stability performance of short cavity Er-doped fiber lasers, Opt. Commun. 283 (6) (2010) 1067–1070.
[1] K. Mondal, P.R. Chaudhuri, Designing high performance Er+3-doped fiber amplifier in triangular-lattice photonic crystal fiber host towards higher gain, low splice loss, Opt. Laser Technol. 43 (8) (2011) 1436–1441. [2] K. Mondal, P.R. Chaudhuri, Investigation of structural dependence of host erbiumdoped triangular-lattice PCF on lasing properties and design of high performance laser, J. Mod. Optic. 60 (15) (2013) 1247–1252. [3] P. Yan, R. Lin, H. Chen, et al., Topological insulator solution filled in photonic crystal fiber for passive mode-locked fiber Laser, IEEE Photonic. Technol. Lett. 27 (3) (2015) 264–267. [4] J.A. Sánchez-martín, M.A. Rebolledo, J.M. Álvarez, et al., Erbium-doped photonic crystal fiber lasers optimization by microstructure control: experimental study analysis, Appl. Phys. B: Laser Opt. 110 (4) (2013) 579–584. [5] S. Hilaire, D. Pagnoux, P. Roy, et al., Numerical study of single mode Er-doped microstructured fibers: influence of geometrical parameters on amplifier performances, Opt. Express 14 (22) (2006) 10787–10865. [6] K. Furusawa, T. Kogure, J.K. Sahu, et al., Efficient low-threshold lasers based on an erbium-doped holey fiber, IEEE Photonic. Technol. Lett. 17 (1) (2005) 25–27. [7] Y. Zhang, B. Lin, S.C. Tjin, et al., Refractive index sensing based on higher-order mode reflection of a microfiber Bragg grating, Opt. Express 18 (25) (2010) 26345–26350. [8] N.F. Naim, A. Bakar, et al., Fault identification and localization for ethernet passive optical network using L-band ASE source and various types of fiber Bragg grating, Opt. Fiber Technol. 40 (2018) 159–164. [9] P. Laporta, S. Taccheo, S. Longhi, et al., Erbium-ytterbium microlasers: optical properties and lasing characteristics, Opt. Mater. 11 (2) (1999) 269–288.
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