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Proceedings Paper • Open Access

Understanding the characteristics of gain saturation for homogeneously broadened laser medium from the point of view of the bandwidth
Author(s): Geguo Du

Paper Abstract

It is very important to understand the characteristics of gain saturation for homogeneously broadened laser medium. Assuming a Lorentzian lineshape function with a linewidth of ΔνH, we have derived the analytical functions of the gain coefficient under three different conditions: 1) a small and 2) a large signal incident on the medium respectively, and 3) a small signal accompanied by a large signal simultaneously incident on the medium. We have found that the bandwidth Δν of the gain coefficient is equal to the linewidth ΔνH for condition 1) and 3) while it is Δν = √1+Iν1 / IsΔνH for condition 2). Here, Iν1 and Is are the intensity of the large signal and the saturation intensity at the center frequency ν0, respectively. The reasons are also presented for such results. For condition 2), gain saturation effect is strongly dependent on the frequency of the large signal: the more the frequency deviates from the center frequency, the weaker the gain saturation effect. This results an increase of the bandwidth. For condition 3), the intensity of the large signal only changes the distribution of populations on the upper and lower energy levels. Hence, the shape of the gain coefficient does not change with the gain reduction of the small signal, thus, its bandwidth remains the same.

Paper Details

Date Published: 3 June 2007
PDF: 4 pages
Proc. SPIE 9665, Tenth International Topical Meeting on Education and Training in Optics and Photonics, 96650B (3 June 2007); doi: 10.1117/12.2207474
Show Author Affiliations
Geguo Du, Shenzhen Univ. (China)


Published in SPIE Proceedings Vol. 9665:
Tenth International Topical Meeting on Education and Training in Optics and Photonics
Marc Nantel, Editor(s)

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