Abstract

We report a novel center-sunken and cladding-trenched Yb-doped fiber, which was fabricated by a modified chemical vapor deposition process with a solution-doping technique. The simulation results showed that the fiber with a core diameter of 40 µm and a numerical aperture of 0.043 has a 1217 µm2 effective mode area at 1080 nm. It is also disclosed that the leakage loss can be reduced lower than 0.01 dB/m for the LP01 mode, while over 80 dB/m for the LP11 mode by optimizing the bending radius as 14 cm. A 456 W laser output was observed in a MOPA structure. The laser slope efficiency was measured to be 79% and the M2 was less than 1.1, which confirmed the single mode operation of the large mode area center-sunken cladding-trenched Yb-doped fiber.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

High-power all-fiber lasers have been witnessed tremendous success in scientific research and industrial applications due to their excellent beam quality, better thermal management, higher coupling efficiency and flexibility [1–3]. However, the nonlinear effects and thermal effects caused by high optical intensity in the core, greatly limit the further increase of output power [4]. Subsequently, the large-mode-area (LMA) fibers were developed to overcome these problems [5].

In conventional all-solid LMA fibers, enlarging the core size is a general method to increase the effective mode area. Ultra-low numerical aperture (NA) and cladding control technology are necessary to ensure the single-mode operation in a large size core. D. Jain et al. [6] reported an ultra-low NA (as low as 0.038) Yb-doped fiber with a core diameter of 35 μm, which has an effective mode area of 700 μm2 and a Gaussian output beam. Additionally, the gain-guided index antiguided fiber [7], in which the refractive index of core is lower than inner cladding, also exhibited single transverse mode transmission even with a 100 μm core diameter. Other kinds of fibers utilizing cladding control technologies, such as Leakage Channel Fiber (LCF) [8–11], Multi-trench fiber (MTF) [12–15], Chirally Coupled Core (3C) fibers [16], Very large mode area (VLMA) fiber [17] and All Solid Photonic Bandgap Fiber (ASPBF) [18,19], have also been developed to suppress higher order modes (HOM) and efficiently increase the threshold of nonlinear effects. However, LCF, 3C fibers, VLMA fiber and ASPBF have complex structures and hard to be prepare, in addition, the MTF is passive, and only used as power transmission. And most of the structures exhibit large bending loss of fundamental mode (FM) even in a small bending radius.

In this work, we proposed and fabricated a center-sunken and cladding-trenched large mode area Yb-doped fiber (CSCTF). The simulation showed that the center sunken of the refractive index profile would increase the effective mode area, and the multi-trench cladding decreased the FM loss and increased that of the HOM. The Yb-doped CSCTF was prepared using modified chemical vapor deposition process with solution-doping technique. The fiber core has a diameter of 40 μm and a low NA of 0.043. The effective mode area is around 1217 um2 at 14 cm bending radius. The fiber bending radius of the FM bending loss was calculated to be less than 0.01 dB/m and the HOM bending loss was higher than 80 dB/m. A laser slope efficiency of 79% and a maximum output power of 456 W were obtained in the master oscillator power amplifier which was only limited by the available pump sources. The beam quality M2 was measured to be less than 1.1, exhibiting excellent single mode performance in the Yb-doped CSCTF.

2. Fabrication of a center-sunken cladding-trenched Yb-doped fiber

Generally, we can realize uniform profile of core refractive index by controlling the dopants incorporation such as soot porosity, soot oxidation temperature, solution doping condition [20] and collapse pressure. In order to obtain a center sunken profile, the SF6 was introduced into F300 tube in the process of soot deposition. SF6 can react with SiO2 and generate SiF4, which can decrease the refractive index of core region. A series of fiber preforms were deposited with the process mentioned above. Through optimizing the fabrication process we obtained an Yb-doped CSCT fiber. The refractive index profiles (RIPs) of the preform was measured by PK104 (PHOTO KINETICS). Two cross-sections which were 100 mm and 200 mm away from the end of the preform were selected as the measuring points and the RIPs at the two cross-section were plotted in Fig. 1(a). It is shown that the refractive index distributions of the two interfaces are almost coincidence, implying excellent uniformity along the axis of the preform. Moreover, the center sunken section of the RIP maintains flat along the cross-section. It is shown that the refractive index difference of n1 to n2 was about 0.0004, and the depth of the trench from n3 to n4 was about 0.00035. Correspondingly, the NA of n1 to cladding n3 was determined to be 0.043 and can be defined as the NA of the fiber core. The observed peaks at the center of the profiles are within measurement error and can be neglected.

 

Fig. 1 Index profile of (a) Yb doped fiber preform, (b) Yb concentration of fiber.

Download Full Size | PPT Slide | PDF

The preform was firstly processed into a D-shape to facilitate the cladding pumping by breaking the circular symmetry. Then it was drawn into a fiber with core diameter of 40 μm and cladding diameter of 400 μm. The fiber was coated with low index polymer which provides a nominal pump cladding with NA of 0.46 to allow pumping light guided in the cladding. The ytterbium concentration distribution was measured by Electron Probe Micro Analysis (EPMA) which was shown in Fig. 1(b). It indicates that the distribution of ytterbium ions is uniform along the fiber core. The observed peaks at the left of the fiber core profile are merely the measurement artifact.

3. Numerical simulations

A finite element method with Perfectly Matched Layer (PML) was applied to simulate the optical losses of the core modes [21]. A series expension can be established to fit the actual index distribution by following expression:

n(r)=amrm+am1rm1++ar+b, r2=x2+y2
where n(r) is the index profile of the fiber, am to a and b are constant, x and y are the reference coordinate. The mode simulation shows that there is only two guided modes (LP01 mode and LP11 mode) in the center sunken fiber. While there will be four modes in step index fiber with the same NA (V~5.23). Figure 2(a) shows the calculated loss of the LP01 and LP11 modes at 1080 nm. It is shown that the FM loss rapidly decreases with the increase of bending diameter, while the loss of LP11 mode remains at a high level. It is suggested that the criterion of single mode operation can be set supposing that the loss of HOM is over 10 dB/m and the loss of FM is lower than 0.1 dB/m, which can be achieved at a bending diameter of 24 cm in the CSCT fiber. However in view of the practical application of high power lasers, 0.1 dB/m loss for FM is too large. It will dissipate the laser power and cause other thermal problem. So we select 0.01 dB/m of FM as the criterion loss for single mode transmission. An effective area of 1217 μm2 can be achieved (The step index fiber with the same factor is about 720 um2) at a bending diameter of 28 cm and the corresponding mode loss is 0.007 dB/m for FM and 84.5 dB/m for LP11 mode. The loss ratio of FM to HOM is above 12000, and great suppression of HOMs can efficiently mitigate detrimental modal instability phenomenon [22]. To clarify the influence of the trench to the mode loss, we calculated the loss of LP01 and LP11 mode as a function of different trench number at a bending diameter of 28 cm, which is shown in Fig. 2(b). The FM loss is larger than 10 dB/m when there is no trench, but less than 0.01dB/m with 6 trenches. With the increase of trench number, the FM loss decreased while LP11 mode loss increased and then kept at a higher level. When the trench number reaches to 6, the FM loss was reduced to 0.007 dB/m and the LP11 mode loss went up to 84.5 dB/m. The red point corresponds to the fiber with seven trenches, which shows that the trench number over 6 will impose less influence to LP01 and LP11 mode, and the mode loss will reach a stability.

 

Fig. 2 (a) The loss of LP01 and LP11 mode with the bending diameter at 1080 nm. Purple and orange line representation the bend diameter of 0.1 dB/m and 0.01 dB/m respectively at LP01, inset is the electric field profile of LP01 and LP11 with bending diameter of 24 cm. (b) Influence of the different trench to the LP01 mode and LP11 mode.

Download Full Size | PPT Slide | PDF

The above results show that the large effective mode area over 1200 μm2 can be realized in CSCT fiber with a small bending diameter. More specifically, the fiber exhibits excellent mode selection characteristic.

4. Experiment and discussion

The fiber laser slope efficiency was measured in a master oscillator power amplifier system using an 8 m long fiber as shown in Fig. 3(a). Three 200 W fiber-coupled pump diodes modules (supplied by DILAS) operating at wavelength of 976 nm was used as the pump source. The CW seeding laser is working at 1080 nm with a maximum output power of 53 W and the seed structure show in frame. They are both coupled into a pieces of Yb-doped CSCT fiber through a combiner with 20/400 μm pigtail. The fusing point was coated with low index gel. The fiber under test was kept with ~14 cm (+/−0.3 cm) bending radius. Then the Yb-doped fiber was spliced with an end cap to protect the amplifier system. The end cap is a section of ~1 cm coreless fiber was with 4°  angle. Figure 3(b) shows the measured slope efficiency with respect to the absorbed pump power. The Yb-doped fiber length was optimized to 8 m with cut-back method. The fiber cladding absorption coefficient at 976 nm was measured as 1.82 dB/m. The laser output with maximum output power of 456 W and 79% slope efficiency were obtained. No power saturation was observed and further power scaling was only limited by the available pump power. The output spectrum with different output power is shown in Fig. 3(c). The acquired 0.96 nm and 1 nm bandwidth corresponds to the 3 dB bandwidth of seed laser and maximum output power.

 

Fig. 3 (a) Experimental set-up used for amplifier efficiency measurement, (b) output power as a function of pump power and absorbed power, inset shows the output beam at 1 W, 1.5 W and 2 W pump power, (c) output spectrum with different output power.

Download Full Size | PPT Slide | PDF

To explore the single-mode behavior of the CSCT fiber, we used the CCD camera to monitor the output beam from the end cap directly. Figure 3(b) inset shows the obtained output beam at three different pump power levels (1 W, 1.5 W and 2 W). It is shown that only the intensity of the output beam changes and the laser beam maintain Gaussian distribution irrespective of launching conditions.

In order to further evaluate the single-mode behavior of the fiber, a multimode laser beam was injected into the CSCT fiber. Figure 4(a) shows the experiment set-up. Firstly, a 1.5 m long 30/400 Yb-doped fiber (V~5.67) was spliced with the combiner output end and the fiber was placed straight to eliminate the effect of the bending to HOMs. After optimizing the beam path, the M2 of the output beam was measured to be ~2.5 in the x-direction and 2.8 in the y-direction, as shown in Fig. 4(b). The result shows that the HOMs plays the dominate role in the beam. Afterwards, a 1.5m long 40/400 CSCT fiber was spliced with the above 30/400 fiber directly. The 30/400 fiber was still maintained in straight condition. The CSCT fiber was bended with diameter of ~28cm and other experimental conditions were kept the same as above, which was shown in Fig. 4(a). The optimized M2 was measured to be 1.09 in the x-direction and 1.17 in the y-direction, which was shown in Fig. 4(c). This is in good agreement with our simulation result, which indicated a better suppression of the HOMs under bending condition. These measurements verify that an effective single mode operation can be obtained from the center sunken cladding trenched fiber by choosing an appropriate bending diameter to select modes.

 

Fig. 4 (a)Experimental set-up for single mode verification, a 1.5 m long CSCT fiber coiled with 28 cm bending diameter was used in this experiment, (b) M2 measurement of the output mode in 30 µm core fiber, (c) M2 measurement of the output mode in CSCT fiber.

Download Full Size | PPT Slide | PDF

Our optimized MCVD process and solution doping technique has shown the versatility to fabricate center-sunken cladding-trenched rare-earth doped fibers. CSCT fibers are all solid structure and are free from any problems caused by air holes or other complex preparation process. It is important to note that the center sunken structure can reach a large effective mode area comparable with PCF but also maintain a uniform rare-earth ions distribution along the profile. The cladding-trenched can reduce FM power tunneling towards the outer cladding and arise resonant coupling between the HOM and cladding-trenched mode, which increase the ratio between the losses of the HOM and the FM [12, 14, 23]. Furthermore, the multi-trench around the core can offer high suppression to the HOMs (80 dB/m) and low loss for the FM mode (0.01 dB/m), which is hard to realize by other kinds of fibers. The mechanism need to be further investigated in the later experiment. Further works will be focused on increasing the laser power and investigating the characteristic of mode instability in our current design. The top-hat beam [24,25] research is also necessary as well.

5. Conclusions

We have successfully demonstrated an Yb-doped CSCT fiber with a center sunken refractive index core profile and trenched cladding. The fiber was prepared using MCVD technology combined with solution doping method. The fiber has a core diameter of 40 µm and the effective mode area was simulated to be as large as 1217 μm2. The bending radius of 14 cm, the loss of HOMs can be tailored as high as 80 dB/m, and the loss of FM can be controlled as low as 0.01 dB/m, which ensures an effective single-mode operation at 1080 nm. Furthermore, the laser power can reach to 456 W with a 79% slope efficiency and with a beam quality factor M2 less than 1.1. All the results above confirmed that the proposed fiber has a potential application in high power fiber lasers with excellent beam quality.

Funding

The National Key Research and Development Program of China (No. 2016YFB0402200); National Natural Science Foundation of China (Grant No. 61735007).

References and links

1. J. Nilsson and D. N. Payne, “High-power fiber lasers,” Science 332(6032), 921–922 (2011). [CrossRef]   [PubMed]  

2. J. Limpert, T. Schreiber, T. Clausnitzer, K. Zöllner, H. Fuchs, E. Kley, H. Zellmer, and A. Tünnermann, “High-power femtosecond Yb-doped fiber amplifier,” Opt. Express 10(14), 628–638 (2002). [CrossRef]   [PubMed]  

3. R. Selves, J. K. Sahu, L. B. Fu, J. N. Jang, J. Nilsson, A. B. Grudinin, K. H. Ylä-Jarkko, S. A. Alam, P. W. Turner, and J. Moore, “High-power, low-noise, Yb-doped, cladding-pumped, three-level fiber sources at 980 nm,” Opt. Lett. 28(13), 1093–1095 (2003). [CrossRef]   [PubMed]  

4. C. Jauregui, J. Limpert, and A. Tunnermann, “High-power fiber lasers,” Nat. Photonics 7(11), 861–867 (2013). [CrossRef]  

5. G. P. Agrawal, Nonlinear Fiber Optics, 4th ed. (Academic, 2007).

6. D. Jain, Y. Jung, P. Barua, S. Alam, and J. K. Sahu, “Demonstration of ultra-low NA rare-earth doped step index fiber for applications in high power fiber lasers,” Opt. Express 23(6), 7407–7415 (2015). [CrossRef]   [PubMed]  

7. A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006). [CrossRef]  

8. L. Dong, H. A. McKay, L. Fu, M. Ohta, A. Marcinkevicius, S. Suzuki, and M. E. Fermann, “Ytterbium-doped all glass leakage channel fibers with highly fluorine-doped silica pump cladding,” Opt. Express 17(11), 8962–8969 (2009). [CrossRef]   [PubMed]  

9. L. Dong, H. A. McKay, and L. Fu, “All-glass endless single-mode photonic crystal fibers,” Opt. Lett. 33(21), 2440–2442 (2008). [CrossRef]   [PubMed]  

10. G. Gu, F. Kong, T. W. Hawkins, M. Jones, and L. Dong, “Extending mode areas of single-mode all-solid photonic bandgap fibers,” Opt. Express 23(7), 9147–9156 (2015). [CrossRef]   [PubMed]  

11. L. Fu, H. A. McKay, and L. Dong, “Extremely large mode area optical fibers formed by thermal stress,” Opt. Express 17(14), 11782–11793 (2009). [CrossRef]   [PubMed]  

12. D. Jain, C. Baskiotis, and J. K. Sahu, “Mode area scaling with multi-trench rod-type fibers,” Opt. Express 21(2), 1448–1455 (2013). [CrossRef]   [PubMed]  

13. D. Jain, Y. Jung, M. Nunez-Velazquez, and J. K. Sahu, “Extending single mode performance of all-solid large-mode-area single trench fiber,” Opt. Express 22(25), 31078–31091 (2014). [CrossRef]   [PubMed]  

14. D. Jain, C. Baskiotis, and J. K. Sahu, “Bending performance of large mode area multi-trench fibers,” Opt. Express 21(22), 26663–26670 (2013). [CrossRef]   [PubMed]  

15. D. Jain, Y. Jung, J. Kim, and J. K. Sahu, “Robust single-mode all-solid multi-trench fiber with large effective mode area,” Opt. Lett. 39(17), 5200–5203 (2014). [CrossRef]   [PubMed]  

16. X. Ma, C. Zhu, I. N. Hu, A. Kaplan, and A. Galvanauskas, “Single-mode chirally-coupled-core fibers with larger than 50 µm diameter cores,” Opt. Express 22(8), 9206–9219 (2014). [CrossRef]   [PubMed]  

17. H. Wei, K. Chen, Y. Yang, and J. Li, “All-solid very large mode area ytterbium-doped silica microstructured fiber based on accurate control on cladding index,” Opt. Express 24(8), 8978–8987 (2016). [CrossRef]   [PubMed]  

18. K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010). [CrossRef]  

19. M. Kashiwagi, K. Saitoh, K. Takenga, S. Tanigawa, S. Matsuo, and M. Fujimaki, “Low bending loss and effectively single-mode all-solid photonic bandgap fiber with an effective area of effective area of 650 µm2,” Opt. Lett. 37(8), 1292–1294 (2012). [CrossRef]   [PubMed]  

20. V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

21. Y. O. Agha, F. Zolla, A. Nicolet, and S. Guenneau, “On the use of PML for the computation of leaky modes: an application to microstructured optical fibers,” Int. J. Computation Math. Elec. Electron. Eng. 27(1), 95–109 (2008). [CrossRef]  

22. T. Eidam, C. Wirth, C. Jauregui, F. Stutzki, F. Jansen, H. J. Otto, O. Schmidt, T. Schreiber, J. Limpert, and A. Tünnermann, “Experimental observations of the threshold-like onset of mode instabilities in high power fiber amplifiers,” Opt. Express 19(14), 13218–13224 (2011). [CrossRef]   [PubMed]  

23. Z. Zhang, Y. Shi, B. Bian, and J. Lu, “Dependence of leaky mode coupling on loss in photonic crystal fiber with hybrid cladding,” Opt. Express 16(3), 1915–1922 (2008). [CrossRef]   [PubMed]  

24. F. Jansen, F. Stutzki, H.-J. Otto, M. Baumgartl, C. Jauregui, J. Limpert, and A. Tünnermann, “The influence of index-depressions in core-pumped Yb-doped large pitch fibers,” Opt. Express 18(26), 26834–26842 (2010). [CrossRef]   [PubMed]  

25. C. Valentin, P. Calvet, Y. Quiquempois, G. Bouwmans, L. Bigot, Q. Coulombier, M. Douay, K. Delplace, A. Mussot, and E. Hugonnot, “Top-hat beam output of a single-mode microstructured optical fiber: Impact of core index depression,” Opt. Express 21(20), 23250–23260 (2013). [CrossRef]   [PubMed]  

References

  • View by:
  • |
  • |
  • |

  1. J. Nilsson and D. N. Payne, “High-power fiber lasers,” Science 332(6032), 921–922 (2011).
    [Crossref] [PubMed]
  2. J. Limpert, T. Schreiber, T. Clausnitzer, K. Zöllner, H. Fuchs, E. Kley, H. Zellmer, and A. Tünnermann, “High-power femtosecond Yb-doped fiber amplifier,” Opt. Express 10(14), 628–638 (2002).
    [Crossref] [PubMed]
  3. R. Selves, J. K. Sahu, L. B. Fu, J. N. Jang, J. Nilsson, A. B. Grudinin, K. H. Ylä-Jarkko, S. A. Alam, P. W. Turner, and J. Moore, “High-power, low-noise, Yb-doped, cladding-pumped, three-level fiber sources at 980 nm,” Opt. Lett. 28(13), 1093–1095 (2003).
    [Crossref] [PubMed]
  4. C. Jauregui, J. Limpert, and A. Tunnermann, “High-power fiber lasers,” Nat. Photonics 7(11), 861–867 (2013).
    [Crossref]
  5. G. P. Agrawal, Nonlinear Fiber Optics, 4th ed. (Academic, 2007).
  6. D. Jain, Y. Jung, P. Barua, S. Alam, and J. K. Sahu, “Demonstration of ultra-low NA rare-earth doped step index fiber for applications in high power fiber lasers,” Opt. Express 23(6), 7407–7415 (2015).
    [Crossref] [PubMed]
  7. A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
    [Crossref]
  8. L. Dong, H. A. McKay, L. Fu, M. Ohta, A. Marcinkevicius, S. Suzuki, and M. E. Fermann, “Ytterbium-doped all glass leakage channel fibers with highly fluorine-doped silica pump cladding,” Opt. Express 17(11), 8962–8969 (2009).
    [Crossref] [PubMed]
  9. L. Dong, H. A. McKay, and L. Fu, “All-glass endless single-mode photonic crystal fibers,” Opt. Lett. 33(21), 2440–2442 (2008).
    [Crossref] [PubMed]
  10. G. Gu, F. Kong, T. W. Hawkins, M. Jones, and L. Dong, “Extending mode areas of single-mode all-solid photonic bandgap fibers,” Opt. Express 23(7), 9147–9156 (2015).
    [Crossref] [PubMed]
  11. L. Fu, H. A. McKay, and L. Dong, “Extremely large mode area optical fibers formed by thermal stress,” Opt. Express 17(14), 11782–11793 (2009).
    [Crossref] [PubMed]
  12. D. Jain, C. Baskiotis, and J. K. Sahu, “Mode area scaling with multi-trench rod-type fibers,” Opt. Express 21(2), 1448–1455 (2013).
    [Crossref] [PubMed]
  13. D. Jain, Y. Jung, M. Nunez-Velazquez, and J. K. Sahu, “Extending single mode performance of all-solid large-mode-area single trench fiber,” Opt. Express 22(25), 31078–31091 (2014).
    [Crossref] [PubMed]
  14. D. Jain, C. Baskiotis, and J. K. Sahu, “Bending performance of large mode area multi-trench fibers,” Opt. Express 21(22), 26663–26670 (2013).
    [Crossref] [PubMed]
  15. D. Jain, Y. Jung, J. Kim, and J. K. Sahu, “Robust single-mode all-solid multi-trench fiber with large effective mode area,” Opt. Lett. 39(17), 5200–5203 (2014).
    [Crossref] [PubMed]
  16. X. Ma, C. Zhu, I. N. Hu, A. Kaplan, and A. Galvanauskas, “Single-mode chirally-coupled-core fibers with larger than 50 µm diameter cores,” Opt. Express 22(8), 9206–9219 (2014).
    [Crossref] [PubMed]
  17. H. Wei, K. Chen, Y. Yang, and J. Li, “All-solid very large mode area ytterbium-doped silica microstructured fiber based on accurate control on cladding index,” Opt. Express 24(8), 8978–8987 (2016).
    [Crossref] [PubMed]
  18. K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010).
    [Crossref]
  19. M. Kashiwagi, K. Saitoh, K. Takenga, S. Tanigawa, S. Matsuo, and M. Fujimaki, “Low bending loss and effectively single-mode all-solid photonic bandgap fiber with an effective area of effective area of 650 µm2,” Opt. Lett. 37(8), 1292–1294 (2012).
    [Crossref] [PubMed]
  20. V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).
  21. Y. O. Agha, F. Zolla, A. Nicolet, and S. Guenneau, “On the use of PML for the computation of leaky modes: an application to microstructured optical fibers,” Int. J. Computation Math. Elec. Electron. Eng. 27(1), 95–109 (2008).
    [Crossref]
  22. T. Eidam, C. Wirth, C. Jauregui, F. Stutzki, F. Jansen, H. J. Otto, O. Schmidt, T. Schreiber, J. Limpert, and A. Tünnermann, “Experimental observations of the threshold-like onset of mode instabilities in high power fiber amplifiers,” Opt. Express 19(14), 13218–13224 (2011).
    [Crossref] [PubMed]
  23. Z. Zhang, Y. Shi, B. Bian, and J. Lu, “Dependence of leaky mode coupling on loss in photonic crystal fiber with hybrid cladding,” Opt. Express 16(3), 1915–1922 (2008).
    [Crossref] [PubMed]
  24. F. Jansen, F. Stutzki, H.-J. Otto, M. Baumgartl, C. Jauregui, J. Limpert, and A. Tünnermann, “The influence of index-depressions in core-pumped Yb-doped large pitch fibers,” Opt. Express 18(26), 26834–26842 (2010).
    [Crossref] [PubMed]
  25. C. Valentin, P. Calvet, Y. Quiquempois, G. Bouwmans, L. Bigot, Q. Coulombier, M. Douay, K. Delplace, A. Mussot, and E. Hugonnot, “Top-hat beam output of a single-mode microstructured optical fiber: Impact of core index depression,” Opt. Express 21(20), 23250–23260 (2013).
    [Crossref] [PubMed]

2016 (1)

2015 (2)

2014 (3)

2013 (4)

2012 (1)

2011 (2)

2010 (2)

K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010).
[Crossref]

F. Jansen, F. Stutzki, H.-J. Otto, M. Baumgartl, C. Jauregui, J. Limpert, and A. Tünnermann, “The influence of index-depressions in core-pumped Yb-doped large pitch fibers,” Opt. Express 18(26), 26834–26842 (2010).
[Crossref] [PubMed]

2009 (2)

2008 (3)

2006 (1)

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

2003 (1)

2002 (1)

2001 (1)

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Agha, Y. O.

Y. O. Agha, F. Zolla, A. Nicolet, and S. Guenneau, “On the use of PML for the computation of leaky modes: an application to microstructured optical fibers,” Int. J. Computation Math. Elec. Electron. Eng. 27(1), 95–109 (2008).
[Crossref]

Alam, S.

Alam, S. A.

Ballato, J.

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Barua, P.

Baskiotis, C.

Baumgartl, M.

Berka, Z.

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Berkova, D.

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Bian, B.

Bigot, L.

Bouwmans, G.

Calvet, P.

Chen, K.

Chen, Y.

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Chomat, M.

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Clausnitzer, T.

Coulombier, Q.

Delplace, K.

Dong, L.

Douay, M.

Eidam, T.

Fermann, M. E.

Foy, M. B.

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Fu, L.

Fu, L. B.

Fuchs, H.

Fujimaki, M.

Galvanauskas, A.

Grudinin, A. B.

Gu, G.

Guenneau, S.

Y. O. Agha, F. Zolla, A. Nicolet, and S. Guenneau, “On the use of PML for the computation of leaky modes: an application to microstructured optical fibers,” Int. J. Computation Math. Elec. Electron. Eng. 27(1), 95–109 (2008).
[Crossref]

Hawkins, T. W.

Hawkins, W.

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Hayer, M.

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Hu, I. N.

Hugonnot, E.

Jain, D.

Jang, J. N.

Jansen, F.

Jauregui, C.

Jones, M.

Jung, Y.

Kaplan, A.

Kashiwagi, M.

Kasik, I.

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Kim, J.

Kley, E.

Kong, F.

Koshiba, M.

K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010).
[Crossref]

Langrova, A.

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Li, J.

Limpert, J.

Lu, J.

Ma, X.

Marcinkevicius, A.

Matejec, V.

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Matsuo, S.

McKay, H. A.

Moore, J.

Murao, T.

K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010).
[Crossref]

Mussot, A.

Nicolet, A.

Y. O. Agha, F. Zolla, A. Nicolet, and S. Guenneau, “On the use of PML for the computation of leaky modes: an application to microstructured optical fibers,” Int. J. Computation Math. Elec. Electron. Eng. 27(1), 95–109 (2008).
[Crossref]

Nilsson, J.

Nunez-Velazquez, M.

Ohta, M.

Otto, H. J.

Otto, H.-J.

Payne, D. N.

J. Nilsson and D. N. Payne, “High-power fiber lasers,” Science 332(6032), 921–922 (2011).
[Crossref] [PubMed]

Quiquempois, Y.

Richardson, M. C.

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Rosa, L.

K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010).
[Crossref]

Sahu, J. K.

Saitoh, K.

M. Kashiwagi, K. Saitoh, K. Takenga, S. Tanigawa, S. Matsuo, and M. Fujimaki, “Low bending loss and effectively single-mode all-solid photonic bandgap fiber with an effective area of effective area of 650 µm2,” Opt. Lett. 37(8), 1292–1294 (2012).
[Crossref] [PubMed]

K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010).
[Crossref]

Schmidt, O.

Schreiber, T.

Selves, R.

Shi, Y.

Siegman, A. E.

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Stutzki, F.

Sudesh, V.

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Suzuki, S.

Takenga, K.

Tanigawa, S.

Tunnermann, A.

C. Jauregui, J. Limpert, and A. Tunnermann, “High-power fiber lasers,” Nat. Photonics 7(11), 861–867 (2013).
[Crossref]

Tünnermann, A.

Turner, P. W.

Valentin, C.

Wei, H.

Wirth, C.

Yang, Y.

Ylä-Jarkko, K. H.

Zellmer, H.

Zhang, Z.

Zhu, C.

Zolla, F.

Y. O. Agha, F. Zolla, A. Nicolet, and S. Guenneau, “On the use of PML for the computation of leaky modes: an application to microstructured optical fibers,” Int. J. Computation Math. Elec. Electron. Eng. 27(1), 95–109 (2008).
[Crossref]

Zöllner, K.

Appl. Phys. Lett. (1)

A. E. Siegman, Y. Chen, V. Sudesh, M. C. Richardson, M. B. Foy, W. Hawkins, and J. Ballato, “Confined propagation and near single-mode laser oscillation in a gain-guided, index antiguided iptical fiber,” Appl. Phys. Lett. 89(25), 251101 (2006).
[Crossref]

Ceram. Silik. (1)

V. Matejec, I. Kasik, D. Berkova, M. Hayer, M. Chomat, Z. Berka, and A. Langrova, “Properties of optical fiber performs prepared by inner coating of substrate tubes,” Ceram. Silik. 45(2), 62–69 (2001).

Int. J. Computation Math. Elec. Electron. Eng. (1)

Y. O. Agha, F. Zolla, A. Nicolet, and S. Guenneau, “On the use of PML for the computation of leaky modes: an application to microstructured optical fibers,” Int. J. Computation Math. Elec. Electron. Eng. 27(1), 95–109 (2008).
[Crossref]

Nat. Photonics (1)

C. Jauregui, J. Limpert, and A. Tunnermann, “High-power fiber lasers,” Nat. Photonics 7(11), 861–867 (2013).
[Crossref]

Opt. Express (14)

J. Limpert, T. Schreiber, T. Clausnitzer, K. Zöllner, H. Fuchs, E. Kley, H. Zellmer, and A. Tünnermann, “High-power femtosecond Yb-doped fiber amplifier,” Opt. Express 10(14), 628–638 (2002).
[Crossref] [PubMed]

L. Dong, H. A. McKay, L. Fu, M. Ohta, A. Marcinkevicius, S. Suzuki, and M. E. Fermann, “Ytterbium-doped all glass leakage channel fibers with highly fluorine-doped silica pump cladding,” Opt. Express 17(11), 8962–8969 (2009).
[Crossref] [PubMed]

D. Jain, Y. Jung, P. Barua, S. Alam, and J. K. Sahu, “Demonstration of ultra-low NA rare-earth doped step index fiber for applications in high power fiber lasers,” Opt. Express 23(6), 7407–7415 (2015).
[Crossref] [PubMed]

G. Gu, F. Kong, T. W. Hawkins, M. Jones, and L. Dong, “Extending mode areas of single-mode all-solid photonic bandgap fibers,” Opt. Express 23(7), 9147–9156 (2015).
[Crossref] [PubMed]

L. Fu, H. A. McKay, and L. Dong, “Extremely large mode area optical fibers formed by thermal stress,” Opt. Express 17(14), 11782–11793 (2009).
[Crossref] [PubMed]

D. Jain, C. Baskiotis, and J. K. Sahu, “Mode area scaling with multi-trench rod-type fibers,” Opt. Express 21(2), 1448–1455 (2013).
[Crossref] [PubMed]

D. Jain, Y. Jung, M. Nunez-Velazquez, and J. K. Sahu, “Extending single mode performance of all-solid large-mode-area single trench fiber,” Opt. Express 22(25), 31078–31091 (2014).
[Crossref] [PubMed]

D. Jain, C. Baskiotis, and J. K. Sahu, “Bending performance of large mode area multi-trench fibers,” Opt. Express 21(22), 26663–26670 (2013).
[Crossref] [PubMed]

X. Ma, C. Zhu, I. N. Hu, A. Kaplan, and A. Galvanauskas, “Single-mode chirally-coupled-core fibers with larger than 50 µm diameter cores,” Opt. Express 22(8), 9206–9219 (2014).
[Crossref] [PubMed]

H. Wei, K. Chen, Y. Yang, and J. Li, “All-solid very large mode area ytterbium-doped silica microstructured fiber based on accurate control on cladding index,” Opt. Express 24(8), 8978–8987 (2016).
[Crossref] [PubMed]

T. Eidam, C. Wirth, C. Jauregui, F. Stutzki, F. Jansen, H. J. Otto, O. Schmidt, T. Schreiber, J. Limpert, and A. Tünnermann, “Experimental observations of the threshold-like onset of mode instabilities in high power fiber amplifiers,” Opt. Express 19(14), 13218–13224 (2011).
[Crossref] [PubMed]

Z. Zhang, Y. Shi, B. Bian, and J. Lu, “Dependence of leaky mode coupling on loss in photonic crystal fiber with hybrid cladding,” Opt. Express 16(3), 1915–1922 (2008).
[Crossref] [PubMed]

F. Jansen, F. Stutzki, H.-J. Otto, M. Baumgartl, C. Jauregui, J. Limpert, and A. Tünnermann, “The influence of index-depressions in core-pumped Yb-doped large pitch fibers,” Opt. Express 18(26), 26834–26842 (2010).
[Crossref] [PubMed]

C. Valentin, P. Calvet, Y. Quiquempois, G. Bouwmans, L. Bigot, Q. Coulombier, M. Douay, K. Delplace, A. Mussot, and E. Hugonnot, “Top-hat beam output of a single-mode microstructured optical fiber: Impact of core index depression,” Opt. Express 21(20), 23250–23260 (2013).
[Crossref] [PubMed]

Opt. Fiber Technol. (1)

K. Saitoh, T. Murao, L. Rosa, and M. Koshiba, “Effective area limit of large-mode-area solid-core photonic bandgap fibers for fiber laser applications,” Opt. Fiber Technol. 16(6), 409–418 (2010).
[Crossref]

Opt. Lett. (4)

Science (1)

J. Nilsson and D. N. Payne, “High-power fiber lasers,” Science 332(6032), 921–922 (2011).
[Crossref] [PubMed]

Other (1)

G. P. Agrawal, Nonlinear Fiber Optics, 4th ed. (Academic, 2007).

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (4)

Fig. 1
Fig. 1 Index profile of (a) Yb doped fiber preform, (b) Yb concentration of fiber.
Fig. 2
Fig. 2 (a) The loss of LP01 and LP11 mode with the bending diameter at 1080 nm. Purple and orange line representation the bend diameter of 0.1 dB/m and 0.01 dB/m respectively at LP01, inset is the electric field profile of LP01 and LP11 with bending diameter of 24 cm. (b) Influence of the different trench to the LP01 mode and LP11 mode.
Fig. 3
Fig. 3 (a) Experimental set-up used for amplifier efficiency measurement, (b) output power as a function of pump power and absorbed power, inset shows the output beam at 1 W, 1.5 W and 2 W pump power, (c) output spectrum with different output power.
Fig. 4
Fig. 4 (a)Experimental set-up for single mode verification, a 1.5 m long CSCT fiber coiled with 28 cm bending diameter was used in this experiment, (b) M2 measurement of the output mode in 30 µm core fiber, (c) M2 measurement of the output mode in CSCT fiber.

Equations (1)

Equations on this page are rendered with MathJax. Learn more.

n ( r ) = a m r m + a m 1 r m 1 + + a r + b ,   r 2 = x 2 + y 2

Metrics