The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system

M. Ito; Y. Hayano; Y. Saito; H. Takami; M. Iye; M. Hattori; S. Oya; M. Watanabe; K. Akagawa; S. A. Colley; T. I. Gorota; O. Guyon

doi:10.1117/12.856341

The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system

M. Ito, Y. Hayano, Y. Saito, H. Takami, M. Iye, M. Hattori, S. Oya, M. Watanabe, K. Akagawa, S. A. Colley, T. I. Gorota, O. Guyon

Optical Sciences

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

2 Scopus citations

Abstract

We are commissioning the Laser Guide Star Adaptive Optics (LGS/A0188) system for Subaru Telescope at Hawaii, Mauna Kea. This system utilizes a combination of an all-solid-state mode-locked sum-frequency generation (SFG) laser (1.7GHz-bandwidth, 0.7ns-pulse width) as a light source and single-mode optical fiber for beam transference. However, optical fibers induce nonlinear scattering effects, such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), beyond certain threshold levels in high-power lasers. We measured the laser transmission characteristics of a photonic crystal fiber (PCF) whose mode field diameter (MFD) was 11 μ m, and a step index fiber (SIF) cable whose MFD was 4.2 μ m to evaluate the threshold levels for non-linear effects. We observed SRS in the 200-m-long SIF when we input 1.3W. The material losses of them were 10db/km and 6.4dB/km, respectively. However, SRS and SBS were not induced in the 200-m-long PCF, even for an input power of 5.3W. As a result, we estimated the threshold of SRS to be 33W for the 35-m-long PCF designed for the Subaru LGSAO system. Other than SRS and SBS, we found self phase modulation (SPM) in our PCF. SPM makes the spectrum of the laser beam broaden and it causes less efficiency of generating bright LGS. We measured width of the spectrum by spectrum analyzer. As the result, we found it was 9.1GHz of full width half maximum (FWHM) in comparison with the original FWHM of our laser spectrum, 2.1GHz. This shows 70% of the laser energy for brightening the LGS was lost. We also measured the brightness of the LGS and evaluated its relationship with wavelength of the laser. The LGS' s brightness showed a peculiar tendency that did not be extinguish even though the wavelength has varied about 2pm. The tendency was not shown with the experiment using sodium gas cell. Therefore, it may be concerned the environment of the sodium layer in the mesosphere.

Original language	English (US)
Title of host publication	Adaptive Optics Systems II
Edition	PART 1
DOIs	https://doi.org/10.1117/12.856341
State	Published - 2010
Event	Adaptive Optics Systems II - San Diego, CA, United States Duration: Jun 27 2010 → Jul 2 2010

Publication series

Name	Proceedings of SPIE - The International Society for Optical Engineering
Number	PART 1
Volume	7736
ISSN (Print)	0277-786X

Other

Other	Adaptive Optics Systems II
Country/Territory	United States
City	San Diego, CA
Period	6/27/10 → 7/2/10

Keywords

Adaptive optics
Laser guide star
Nonlinear effect
Optical fiber

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Computer Science Applications
Applied Mathematics
Electrical and Electronic Engineering

Access to Document

10.1117/12.856341

Cite this

Ito, M., Hayano, Y., Saito, Y., Takami, H., Iye, M., Hattori, M., Oya, S., Watanabe, M., Akagawa, K., Colley, S. A., Gorota, T. I., & Guyon, O. (2010). The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system. In Adaptive Optics Systems II (PART 1 ed.). Article 773651 (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 7736, No. PART 1). https://doi.org/10.1117/12.856341

The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system. / Ito, M.; Hayano, Y.; Saito, Y. et al.
Adaptive Optics Systems II. PART 1. ed. 2010. 773651 (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 7736, No. PART 1).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Ito, M, Hayano, Y, Saito, Y, Takami, H, Iye, M, Hattori, M, Oya, S, Watanabe, M, Akagawa, K, Colley, SA, Gorota, TI & Guyon, O 2010, The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system. in Adaptive Optics Systems II. PART 1 edn, 773651, Proceedings of SPIE - The International Society for Optical Engineering, no. PART 1, vol. 7736, Adaptive Optics Systems II, San Diego, CA, United States, 6/27/10. https://doi.org/10.1117/12.856341

@inproceedings{6dd68fa4af43465683557c35ef97a320,

title = "The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system",

abstract = "We are commissioning the Laser Guide Star Adaptive Optics (LGS/A0188) system for Subaru Telescope at Hawaii, Mauna Kea. This system utilizes a combination of an all-solid-state mode-locked sum-frequency generation (SFG) laser (1.7GHz-bandwidth, 0.7ns-pulse width) as a light source and single-mode optical fiber for beam transference. However, optical fibers induce nonlinear scattering effects, such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), beyond certain threshold levels in high-power lasers. We measured the laser transmission characteristics of a photonic crystal fiber (PCF) whose mode field diameter (MFD) was 11 μ m, and a step index fiber (SIF) cable whose MFD was 4.2 μ m to evaluate the threshold levels for non-linear effects. We observed SRS in the 200-m-long SIF when we input 1.3W. The material losses of them were 10db/km and 6.4dB/km, respectively. However, SRS and SBS were not induced in the 200-m-long PCF, even for an input power of 5.3W. As a result, we estimated the threshold of SRS to be 33W for the 35-m-long PCF designed for the Subaru LGSAO system. Other than SRS and SBS, we found self phase modulation (SPM) in our PCF. SPM makes the spectrum of the laser beam broaden and it causes less efficiency of generating bright LGS. We measured width of the spectrum by spectrum analyzer. As the result, we found it was 9.1GHz of full width half maximum (FWHM) in comparison with the original FWHM of our laser spectrum, 2.1GHz. This shows 70% of the laser energy for brightening the LGS was lost. We also measured the brightness of the LGS and evaluated its relationship with wavelength of the laser. The LGS' s brightness showed a peculiar tendency that did not be extinguish even though the wavelength has varied about 2pm. The tendency was not shown with the experiment using sodium gas cell. Therefore, it may be concerned the environment of the sodium layer in the mesosphere.",

keywords = "Adaptive optics, Laser guide star, Nonlinear effect, Optical fiber",

author = "M. Ito and Y. Hayano and Y. Saito and H. Takami and M. Iye and M. Hattori and S. Oya and M. Watanabe and K. Akagawa and Colley, {S. A.} and Gorota, {T. I.} and O. Guyon",

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AU - Ito, M.

AU - Hayano, Y.

AU - Saito, Y.

AU - Takami, H.

AU - Iye, M.

AU - Hattori, M.

AU - Oya, S.

AU - Watanabe, M.

AU - Akagawa, K.

AU - Colley, S. A.

AU - Gorota, T. I.

AU - Guyon, O.

PY - 2010

Y1 - 2010

N2 - We are commissioning the Laser Guide Star Adaptive Optics (LGS/A0188) system for Subaru Telescope at Hawaii, Mauna Kea. This system utilizes a combination of an all-solid-state mode-locked sum-frequency generation (SFG) laser (1.7GHz-bandwidth, 0.7ns-pulse width) as a light source and single-mode optical fiber for beam transference. However, optical fibers induce nonlinear scattering effects, such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), beyond certain threshold levels in high-power lasers. We measured the laser transmission characteristics of a photonic crystal fiber (PCF) whose mode field diameter (MFD) was 11 μ m, and a step index fiber (SIF) cable whose MFD was 4.2 μ m to evaluate the threshold levels for non-linear effects. We observed SRS in the 200-m-long SIF when we input 1.3W. The material losses of them were 10db/km and 6.4dB/km, respectively. However, SRS and SBS were not induced in the 200-m-long PCF, even for an input power of 5.3W. As a result, we estimated the threshold of SRS to be 33W for the 35-m-long PCF designed for the Subaru LGSAO system. Other than SRS and SBS, we found self phase modulation (SPM) in our PCF. SPM makes the spectrum of the laser beam broaden and it causes less efficiency of generating bright LGS. We measured width of the spectrum by spectrum analyzer. As the result, we found it was 9.1GHz of full width half maximum (FWHM) in comparison with the original FWHM of our laser spectrum, 2.1GHz. This shows 70% of the laser energy for brightening the LGS was lost. We also measured the brightness of the LGS and evaluated its relationship with wavelength of the laser. The LGS' s brightness showed a peculiar tendency that did not be extinguish even though the wavelength has varied about 2pm. The tendency was not shown with the experiment using sodium gas cell. Therefore, it may be concerned the environment of the sodium layer in the mesosphere.

AB - We are commissioning the Laser Guide Star Adaptive Optics (LGS/A0188) system for Subaru Telescope at Hawaii, Mauna Kea. This system utilizes a combination of an all-solid-state mode-locked sum-frequency generation (SFG) laser (1.7GHz-bandwidth, 0.7ns-pulse width) as a light source and single-mode optical fiber for beam transference. However, optical fibers induce nonlinear scattering effects, such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), beyond certain threshold levels in high-power lasers. We measured the laser transmission characteristics of a photonic crystal fiber (PCF) whose mode field diameter (MFD) was 11 μ m, and a step index fiber (SIF) cable whose MFD was 4.2 μ m to evaluate the threshold levels for non-linear effects. We observed SRS in the 200-m-long SIF when we input 1.3W. The material losses of them were 10db/km and 6.4dB/km, respectively. However, SRS and SBS were not induced in the 200-m-long PCF, even for an input power of 5.3W. As a result, we estimated the threshold of SRS to be 33W for the 35-m-long PCF designed for the Subaru LGSAO system. Other than SRS and SBS, we found self phase modulation (SPM) in our PCF. SPM makes the spectrum of the laser beam broaden and it causes less efficiency of generating bright LGS. We measured width of the spectrum by spectrum analyzer. As the result, we found it was 9.1GHz of full width half maximum (FWHM) in comparison with the original FWHM of our laser spectrum, 2.1GHz. This shows 70% of the laser energy for brightening the LGS was lost. We also measured the brightness of the LGS and evaluated its relationship with wavelength of the laser. The LGS' s brightness showed a peculiar tendency that did not be extinguish even though the wavelength has varied about 2pm. The tendency was not shown with the experiment using sodium gas cell. Therefore, it may be concerned the environment of the sodium layer in the mesosphere.

KW - Adaptive optics

KW - Laser guide star

KW - Nonlinear effect

KW - Optical fiber

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The characteristics of laser-transmission and guide star's brightness for Subaru LGS/AO188 system

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