OSA's Digital Library

Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 17, Iss. 25 — Dec. 7, 2009
  • pp: 22499–22504
« Show journal navigation

An 88 fs fiber soliton laser using a quantum well saturable absorber with an ultrafast intersubband transition

Fumio Shohda, Masataka Nakazawa, Ryoichi Akimoto, and Hiroshi Ishikawa  »View Author Affiliations


Optics Express, Vol. 17, Issue 25, pp. 22499-22504 (2009)
http://dx.doi.org/10.1364/OE.17.022499


View Full Text Article

Acrobat PDF (235 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

We demonstrate a 1.5 μm passively mode-locked fiber laser using an intersubband transition (ISBT) in a quantum well as a saturable absorber. The saturable absorption characteristic of faster than 1 ps in the ISBT was utilized for femtosecond pulse generation. We designed the laser cavity as a soliton laser, which enabled us to generate a stable pulse. As a result, an 88 fs, 42 MHz soliton pulse was successfully generated.

© 2009 OSA

1. Introduction

There is a growing demand for femtosecond pulse lasers in various industrial fields including optical communication, all-optical signal processing, optical metrology and bio-medical technology. Passively mode-locked fiber lasers have been widely used to generate such ultra-short optical pulses because they have a simple structure that does not require any external active devices for mode-locking. Passive mode-locking can be easily achieved simply by employing a saturable absorption effect, where the light absorption decreases with increasing light intensity. Semiconductor-based saturable absorber mirrors (SESAM) [1

1. U. Keller, D. A. Miller, G. D. Boyd, T. H. Chiu, J. F. Ferguson, and M. T. Asom, “Solid-state low-loss intracavity saturable absorber for Nd:YLF lasers: an antiresonant semiconductor Fabry-Perot saturable absorber,” Opt. Lett. 17(7), 505–507 ( 1992). [CrossRef] [PubMed]

] and single-wall carbon nanotubes (SWNTs) [2

2. Y.-C. Chen, N. R. Raravikar, L. S. Schadler, P. M. Ajayan, Y.-P. Zhao, T.-M. Lu, G.-C. Wang, and X.-C. Zhang, “Ultrafast optical switching properties of single-wall carbon nanotube polymer composites at 1.55 µm,” Appl. Phys. Lett. 81(6), 975–977 ( 2002). [CrossRef]

5

5. M. Nakazawa, S. Nakahara, T. Hirooka, M. Yoshida, T. Kaino, and K. Komatsu, “Polymer saturable absorber materials in the 1.5 microm band using poly-methyl-methacrylate and polystyrene with single-wall carbon nanotubes and their application to a femtosecond laser,” Opt. Lett. 31(7), 915–917 ( 2006). [CrossRef] [PubMed]

] are well-known as ultrafast saturable absorbers. The nonlinear optical effect in fibers can also be used as a mode locker in passively mode-locked lasers [6

6. G. P. Agrawal, Nonlinear Fiber Optics. (Academic Press, 2001.)

], such as nonlinear optical loop mirrors (NOLM) [7

7. A. G. Bulushev, E. M. Dianov, and O. G. Okhotnikov, “Self-starting mode-locked laser with a nonlinear ring resonator,” Opt. Lett. 16(2), 88–90 ( 1991). [CrossRef] [PubMed]

], nonlinear amplifying loop mirrors (NALM) [8

8. I. N. Duling III, “Subpicosecond all-fibre erbium laser,” Electron. Lett. 27(6), 544–545 ( 1991). [CrossRef]

,9

9. D. J. Richardson, R. I. Laming, D. N. Payne, M. W. Phillips, and V. J. Matsas, “320 fs soliton generation with passively mode-locked erbium fibre laser,” Electron. Lett. 27(9), 730–732 ( 1991). [CrossRef]

] and nonlinear polarization rotation (NPR) [10

10. M. Nakazawa, E. Yoshida, T. Sugawa, and Y. Kimura, “Continuum suppressed, uniformly repetitive 136 fs pulse generation from an erbium-doped fibre laser with nonlinear polarisation rotation,” Electron. Lett. 29(15), 1327–1328 ( 1993). [CrossRef]

]. To improve the laser performance, saturable absorbers with large optical nonlinearity, an ultrahigh-speed response time, and high stability are strongly required.

Recently, ultrahigh-speed absorption saturation with an intersubband transition (ISBT) in a quantum well (QW) has attracted a lot of attention since it can be utilized for ultrafast all-optical switching and signal processing [11

11. T. Akiyama, N. Georgiev, T. Mozume, H. Yoshida, A. V. Gopal, and O. Wada, “1.55-μm picosecond all-optical switching by using intersubband absorption in InGaAs-AlAs-AlAsSb coupled quantum wells,” IEEE Photon. Technol. Lett. 14(4), 495–497 ( 2002). [CrossRef]

13

13. R. Akimoto, K. Akita, F. Sasaki, and T. Hasama, “Appl. Sub-picosecond electron relaxation of near-infrared intersubband transitions in n-doped (CdS/ZnSe)/BeTe quantum wells,” Appl. Phys. Lett. 81(16), 2998–3000 ( 2002). [CrossRef]

]. The carrier relaxation time of an ISBT is less than 1 ps, which is much faster than that of electron-hole recombination [14

14. S. Noda, T. Uemura, T. Yamashita, and A. Sasaki, “All-optical modulation using an n-doped quantum-well structure,” J. Appl. Phys. 68(12), 6529–6531 ( 1990). [CrossRef]

]. Moreover, ISBTs have been realized at the optical communication wavelength (λ =1.5 μm) by using several materials including InGaAs/AlAsSb [11

11. T. Akiyama, N. Georgiev, T. Mozume, H. Yoshida, A. V. Gopal, and O. Wada, “1.55-μm picosecond all-optical switching by using intersubband absorption in InGaAs-AlAs-AlAsSb coupled quantum wells,” IEEE Photon. Technol. Lett. 14(4), 495–497 ( 2002). [CrossRef]

], GaN/AlGaN [12

12. C. Gmachl, S. V. Frolov, H. M. Ng, S.-N. G. Chu, and A. Y. Cho, “Sub-picosecond electron scattering time for λ ≅ 1.55 µm intersubband transitions in GaN/AlGaN multiple quantum wells,” Electron. Lett. 37(6), 378–380 ( 2001). [CrossRef]

] and (CdS/ZnSe)/BeTe [13

13. R. Akimoto, K. Akita, F. Sasaki, and T. Hasama, “Appl. Sub-picosecond electron relaxation of near-infrared intersubband transitions in n-doped (CdS/ZnSe)/BeTe quantum wells,” Appl. Phys. Lett. 81(16), 2998–3000 ( 2002). [CrossRef]

]. These properties allow us to realize higher bit rate (above 100 Gbit/s) operation at 1.5 μm. In this paper, we apply the ultrahigh-speed absorption saturation characteristics of an ISBT to a passively mode-locked erbium fiber laser. As a result, we successfully demonstrated 88 fs soliton pulse generation using a II-VI-based ISBT waveguide device. The average output power was approximately 3 mW.

2. Principle of intersubband saturable absorption and the structure of ISBT device

Figure 1
Fig. 1 Principle of ISBT.
shows the principle of an intersubband transition. In a QW, there are several discrete energy levels called subbands. When a high intensity TM pump pulse is injected into a QW subband, the electrons are excited from the ground level to the upper level and the absorption coefficient is saturated. An important feature of the ISBT switch is that the switching response is in the subpicosecond regime due to the ultrafast carrier relaxation time associated with longitudinal optical (LO) phonon emission.

In this work, we employed a II-VI semiconductor-based ISBT device in which the carrier relaxation is more efficient owing to the ease of ionization, and thus the strong interaction between the electron and LO phonon. Figure 2
Fig. 2 Band structure of QW with CdS/ZnSe/BeTe material system.
shows the band structure of a QW employing the CdS/ZnSe/BeTe material system [15

15. G. W. Cong, R. Akimoto, K. Akita, T. Hasama, and H. Ishikawa, “Intersubband absorption with different sublevel couplings in [(CdS/ZnSe/BeTe)/(ZnSe/BeTe)] double quantum wells,” Appl. Phys. Lett. 90(18), 181919 ( 2007). [CrossRef]

]. A CdS/ZnSe well layer was sandwiched between BeTe barrier layers. To realize the ISBT at λ =1.5 μm, the band offset between the well and barrier layer must be sufficiently deep. CdS, ZnSe and BeTe have a type II band structure and this results in a wide-band offset in the conduction band. The band offsets of ZnSe/BeTe and CdS/BeTe were 2.3 and 3.1 eV, respectively. The wide band-gap material system enables us to eliminate the effect of two-photon absorption.

Figure 3
Fig. 3 Optical waveguide structure of ISBT module.
shows the optical waveguide structure of the ISBT device. We employed a mesa waveguide structure with a mesa width of 3 μm and a device length of 300 μm. As shown in the Fig. 3, a multiple QW (MQW) active layer consisting of a multiple CdS/ZnSe/BeTe QW was placed at the center of the core layer. Mixed crystal material, ZnBeSe, was placed above and below the MQW layer to act as optical confinement layers. ZnMgBeSe cladding layers were placed above and below the core layer. To realize highly efficient absorption saturation, a decoupled optic and electronic confinement structure was employed [16

16. K. Akita, R. Akimoto, T. Hasama, H. Ishikawa, and Y. Takanashi, “Intersubband all-optical switching in submicron high-mesa SCH waveguide structure with wide-gap II-VI-based quantum wells,” Electron. Lett. 42(23), 1352–1353 ( 2006). [CrossRef]

]. A photograph of the ISBT device is shown in Fig. 4
Fig. 4 Photograph of ISBT module.
, where the module is equipped with a fiber pig-tailed input and output. The fiber-to-fiber linear loss is approximately 3 dB, which is accounted for by the input and output coupling losses between the fiber and waveguide (1.5 dB each). Here, the TE absorption of the waveguide and the scattering loss were negligible compared with the coupling loss. At λ =1.56 μm, the ISBT linear loss, i.e., the difference between the TE and TM losses, was 9.6 dB.

3. Passively mode-locked femtosecond fiber soliton laser with ISBT module

We installed the ISBT module as a saturable absorber in a passively mode-locked fiber laser and performed a femtosecond pulse generation experiment. Figure 5
Fig. 5 Configuration of passively mode-locked soliton fiber laser with ISBT module as saturable absorber.
shows the configuration of the laser cavity. It is composed of a ring resonator whose cavity length is 4.8 m. An erbium-doped fiber (EDF) with an Er3+ concentration of 7100 ppm was used as the gain medium. The average dispersion of the laser was anomalous ( +2.3 ps/nm/km). We installed a polarization controller to maintain a fixed polarization state (TM mode incident into the ISBT module) in the fiber laser cavity. We maintained the ISBT module at a constant temperature of 25 °C by using a temperature controller to prevent the device from heating up as a result of the thermal effect and to maintain stable laser output characteristics.

To generate a stable optical pulse, we employed the soliton effect in the fiber laser cavity. This was made possible by the anomalous dispersion of the laser cavity. For fundamental soliton propagation, the following two conditions must be satisfied [6

6. G. P. Agrawal, Nonlinear Fiber Optics. (Academic Press, 2001.)

].

PpPsoliton
(1)
Z0L
(2)

Here Pp is the peak power of the pulse circulating in the cavity and Psoliton is the peak power required for a fundamental soliton. Z0 is the soliton period, and L is the cavity length. Psoliton and Z0 are given by
Z0=0.322π2cλ2τFWHM2|Dave|
(3)
Psoliton=3.11λ22πcγ|Dave|τFWHM2
(4)
where c is the velocity of light, γ is the nonlinear coefficient, Dave is the average dispersion of the laser cavity, and τFWHM is the full width at half maximum of the pulse.

Figure 6
Fig. 6 Output characteristics of pulsed oscillation. (a) is laser output power vs pump power. (b) is the time-bandwidth product and pulse width vs pump power.
shows the laser output characteristics. Figure 6(a) shows the relationship between the pump power and the laser output power, and Fig. 6(b) shows the pulse width and the time-bandwidth product against the pump power. When the pump power was increased, first continuous-wave oscillation was obtained above a threshold power of 80 mW and then pulsed oscillation was achieved above 103 mW. Figure 7
Fig. 7 Pulse train waveform with 23.8 ns pulse interval corresponding to a repetition rate of 42 MHz.
shows a pulse train waveform, which we measured with a photodetector and an oscilloscope. This figure reveals that the repetition rate was 42 MHz, which corresponds to a fiber cavity length of 4.8 m. Figure 8
Fig. 8 Laser output characteristics with pump power of 110 mW:(a)autocorrelation waveform, (b) optical spectrum.
shows the autocorrelation waveform and optical spectrum of the fiber laser immediately above the pulsed oscillation threshold (pump power of 110 mW). A pulse width of 129 fs with an average power of 0.8 mW was obtained. The time-bandwidth product was 0.43. As the power was increased, a shorter pulse was obtained and the time-bandwidth product approached 0.32 as shown in Fig. 6(b). The shortest pulse was obtained with a pump power of 180 mW. Figure 9
Fig. 9 Laser output characteristics with pump power of 180 mW:(a) autocorrelation waveform, (b) optical spectrum.
shows the autocorrelation waveform and optical spectrum. A pulse width as short as 88 fs was obtained at a repetition rate of 42 MHz with an average output power of approximately 3 mW. The time-bandwidth product was 0.29, indicating that a nearly transform-limited sech pulse was generated. To check the soliton condition, here we evaluate the peak power required for a soliton, Psoliton, and a soliton period, Z0. Psoliton was calculated to be 802 W, which is close to the peak power of the pulse circulating in the cavity, Pp = 762 W, thus satisfying the condition given by Eq. (1). The soliton period, Z0, was calculated to be 1.3 m, which was shorter than the cavity length of 4.8 m thus satisfying Eq. (2). These results indicate that a stable femtosecond soliton pulse was successfully generated.

4. Conclusion

We demonstrated a passively mode-locked fiber laser, in which we utilized ultrahigh-speed absorption saturation with an ISBT in a semiconductor-QW as a mode locker. An ISBT operating in the 1.5 μm wavelength region was realized by using the (CdS/ZnSe)/BeTe material system. The fiber laser cavity was optimized as a soliton laser to generate a stable fundamental soliton pulse. With these configurations, we successfully generated an 88 fs soliton pulse with an average power of approximately 3 mW at a repetition rate of 42 MHz.

References and links

1.

U. Keller, D. A. Miller, G. D. Boyd, T. H. Chiu, J. F. Ferguson, and M. T. Asom, “Solid-state low-loss intracavity saturable absorber for Nd:YLF lasers: an antiresonant semiconductor Fabry-Perot saturable absorber,” Opt. Lett. 17(7), 505–507 ( 1992). [CrossRef] [PubMed]

2.

Y.-C. Chen, N. R. Raravikar, L. S. Schadler, P. M. Ajayan, Y.-P. Zhao, T.-M. Lu, G.-C. Wang, and X.-C. Zhang, “Ultrafast optical switching properties of single-wall carbon nanotube polymer composites at 1.55 µm,” Appl. Phys. Lett. 81(6), 975–977 ( 2002). [CrossRef]

3.

S. Y. Set, H. Yaguchi, Y. Tanaka, M. Jablonski, Y. Sakakibara, A. Rozhin, M. Tokumoto, H. Kataura, Y. Achiba, and K. Kikuchi, “Mode-locked fiber lasers based on a saturable absorber incorporating carbon nanotubes,” OFC2003, Post-deadline Paper PD44, March 2003.

4.

Y. Sakakibara, M. Tokumoto, S. Tatsuura, Y. Achiba, and H. Kataura, “Optical element, and manufacturing method thereof,” Japan Patent 2001–320383 (2001).

5.

M. Nakazawa, S. Nakahara, T. Hirooka, M. Yoshida, T. Kaino, and K. Komatsu, “Polymer saturable absorber materials in the 1.5 microm band using poly-methyl-methacrylate and polystyrene with single-wall carbon nanotubes and their application to a femtosecond laser,” Opt. Lett. 31(7), 915–917 ( 2006). [CrossRef] [PubMed]

6.

G. P. Agrawal, Nonlinear Fiber Optics. (Academic Press, 2001.)

7.

A. G. Bulushev, E. M. Dianov, and O. G. Okhotnikov, “Self-starting mode-locked laser with a nonlinear ring resonator,” Opt. Lett. 16(2), 88–90 ( 1991). [CrossRef] [PubMed]

8.

I. N. Duling III, “Subpicosecond all-fibre erbium laser,” Electron. Lett. 27(6), 544–545 ( 1991). [CrossRef]

9.

D. J. Richardson, R. I. Laming, D. N. Payne, M. W. Phillips, and V. J. Matsas, “320 fs soliton generation with passively mode-locked erbium fibre laser,” Electron. Lett. 27(9), 730–732 ( 1991). [CrossRef]

10.

M. Nakazawa, E. Yoshida, T. Sugawa, and Y. Kimura, “Continuum suppressed, uniformly repetitive 136 fs pulse generation from an erbium-doped fibre laser with nonlinear polarisation rotation,” Electron. Lett. 29(15), 1327–1328 ( 1993). [CrossRef]

11.

T. Akiyama, N. Georgiev, T. Mozume, H. Yoshida, A. V. Gopal, and O. Wada, “1.55-μm picosecond all-optical switching by using intersubband absorption in InGaAs-AlAs-AlAsSb coupled quantum wells,” IEEE Photon. Technol. Lett. 14(4), 495–497 ( 2002). [CrossRef]

12.

C. Gmachl, S. V. Frolov, H. M. Ng, S.-N. G. Chu, and A. Y. Cho, “Sub-picosecond electron scattering time for λ ≅ 1.55 µm intersubband transitions in GaN/AlGaN multiple quantum wells,” Electron. Lett. 37(6), 378–380 ( 2001). [CrossRef]

13.

R. Akimoto, K. Akita, F. Sasaki, and T. Hasama, “Appl. Sub-picosecond electron relaxation of near-infrared intersubband transitions in n-doped (CdS/ZnSe)/BeTe quantum wells,” Appl. Phys. Lett. 81(16), 2998–3000 ( 2002). [CrossRef]

14.

S. Noda, T. Uemura, T. Yamashita, and A. Sasaki, “All-optical modulation using an n-doped quantum-well structure,” J. Appl. Phys. 68(12), 6529–6531 ( 1990). [CrossRef]

15.

G. W. Cong, R. Akimoto, K. Akita, T. Hasama, and H. Ishikawa, “Intersubband absorption with different sublevel couplings in [(CdS/ZnSe/BeTe)/(ZnSe/BeTe)] double quantum wells,” Appl. Phys. Lett. 90(18), 181919 ( 2007). [CrossRef]

16.

K. Akita, R. Akimoto, T. Hasama, H. Ishikawa, and Y. Takanashi, “Intersubband all-optical switching in submicron high-mesa SCH waveguide structure with wide-gap II-VI-based quantum wells,” Electron. Lett. 42(23), 1352–1353 ( 2006). [CrossRef]

OCIS Codes
(040.4200) Detectors : Multiple quantum well
(140.3500) Lasers and laser optics : Lasers, erbium
(140.3510) Lasers and laser optics : Lasers, fiber
(140.4050) Lasers and laser optics : Mode-locked lasers

ToC Category:
Lasers and Laser Optics

History
Original Manuscript: September 30, 2009
Revised Manuscript: November 14, 2009
Manuscript Accepted: November 17, 2009
Published: November 24, 2009

Citation
Fumio Shohda, Masataka Nakazawa, Ryoichi Akimoto, and Hiroshi Ishikawa, "An 88 fs fiber soliton laser using a quantum well saturable absorber with an ultrafast intersubband transition," Opt. Express 17, 22499-22504 (2009)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-25-22499


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. U. Keller, D. A. Miller, G. D. Boyd, T. H. Chiu, J. F. Ferguson, and M. T. Asom, “Solid-state low-loss intracavity saturable absorber for Nd:YLF lasers: an antiresonant semiconductor Fabry-Perot saturable absorber,” Opt. Lett. 17(7), 505–507 (1992). [CrossRef] [PubMed]
  2. Y.-C. Chen, N. R. Raravikar, L. S. Schadler, P. M. Ajayan, Y.-P. Zhao, T.-M. Lu, G.-C. Wang, and X.-C. Zhang, “Ultrafast optical switching properties of single-wall carbon nanotube polymer composites at 1.55 µm,” Appl. Phys. Lett. 81(6), 975–977 (2002). [CrossRef]
  3. S. Y. Set, H. Yaguchi, Y. Tanaka, M. Jablonski, Y. Sakakibara, A. Rozhin, M. Tokumoto, H. Kataura, Y. Achiba, and K. Kikuchi, “Mode-locked fiber lasers based on a saturable absorber incorporating carbon nanotubes,” OFC2003, Post-deadline Paper PD44, March 2003.
  4. Y. Sakakibara, M. Tokumoto, S. Tatsuura, Y. Achiba, and H. Kataura, “Optical element, and manufacturing method thereof,” Japan Patent 2001–320383 (2001).
  5. M. Nakazawa, S. Nakahara, T. Hirooka, M. Yoshida, T. Kaino, and K. Komatsu, “Polymer saturable absorber materials in the 1.5 microm band using poly-methyl-methacrylate and polystyrene with single-wall carbon nanotubes and their application to a femtosecond laser,” Opt. Lett. 31(7), 915–917 (2006). [CrossRef] [PubMed]
  6. G. P. Agrawal, Nonlinear Fiber Optics. (Academic Press, 2001.)
  7. A. G. Bulushev, E. M. Dianov, and O. G. Okhotnikov, “Self-starting mode-locked laser with a nonlinear ring resonator,” Opt. Lett. 16(2), 88–90 (1991). [CrossRef] [PubMed]
  8. I. N. Duling, “Subpicosecond all-fibre erbium laser,” Electron. Lett. 27(6), 544–545 (1991). [CrossRef]
  9. D. J. Richardson, R. I. Laming, D. N. Payne, M. W. Phillips, and V. J. Matsas, “320 fs soliton generation with passively mode-locked erbium fibre laser,” Electron. Lett. 27(9), 730–732 (1991). [CrossRef]
  10. M. Nakazawa, E. Yoshida, T. Sugawa, and Y. Kimura, “Continuum suppressed, uniformly repetitive 136 fs pulse generation from an erbium-doped fibre laser with nonlinear polarisation rotation,” Electron. Lett. 29(15), 1327–1328 (1993). [CrossRef]
  11. T. Akiyama, N. Georgiev, T. Mozume, H. Yoshida, A. V. Gopal, and O. Wada, “1.55-μm picosecond all-optical switching by using intersubband absorption in InGaAs-AlAs-AlAsSb coupled quantum wells,” IEEE Photon. Technol. Lett. 14(4), 495–497 (2002). [CrossRef]
  12. C. Gmachl, S. V. Frolov, H. M. Ng, S.-N. G. Chu, and A. Y. Cho, “Sub-picosecond electron scattering time for λ ≅ 1.55 µm intersubband transitions in GaN/AlGaN multiple quantum wells,” Electron. Lett. 37(6), 378–380 (2001). [CrossRef]
  13. R. Akimoto, K. Akita, F. Sasaki, and T. Hasama, “Appl. Sub-picosecond electron relaxation of near-infrared intersubband transitions in n-doped (CdS/ZnSe)/BeTe quantum wells,” Appl. Phys. Lett. 81(16), 2998–3000 (2002). [CrossRef]
  14. S. Noda, T. Uemura, T. Yamashita, and A. Sasaki, “All-optical modulation using an n-doped quantum-well structure,” J. Appl. Phys. 68(12), 6529–6531 (1990). [CrossRef]
  15. G. W. Cong, R. Akimoto, K. Akita, T. Hasama, and H. Ishikawa, “Intersubband absorption with different sublevel couplings in [(CdS/ZnSe/BeTe)/(ZnSe/BeTe)] double quantum wells,” Appl. Phys. Lett. 90(18), 181919 (2007). [CrossRef]
  16. K. Akita, R. Akimoto, T. Hasama, H. Ishikawa, and Y. Takanashi, “Intersubband all-optical switching in submicron high-mesa SCH waveguide structure with wide-gap II-VI-based quantum wells,” Electron. Lett. 42(23), 1352–1353 (2006). [CrossRef]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited