Analysis of Gain-Switching Characteristics Including Strong Gain Saturation Effects in Low-Dimensional Semiconductor Lasers
The effects of gain nonlinearities on gain-switched short-pulse-generation characteristics are analyzed via rate equations assuming a nonlinear-gain model including a gain saturation parameter $g_{\text{s}}$ to quantitatively describe the strong gain-saturation nonlinearity in low-dimensional semico...
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| Published in | Japanese Journal of Applied Physics Vol. 51; no. 9; pp. 098001 - 098001-2 |
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| Main Authors | , , , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
The Japan Society of Applied Physics
01.09.2012
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| Online Access | Get full text |
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| Summary: | The effects of gain nonlinearities on gain-switched short-pulse-generation characteristics are analyzed via rate equations assuming a nonlinear-gain model including a gain saturation parameter $g_{\text{s}}$ to quantitatively describe the strong gain-saturation nonlinearity in low-dimensional semiconductor lasers at high carrier densities. It was found that the minimum pulse width and the delay time are mainly determined by $g_{\text{s}}$ rather than a differential gain coefficient $g_{0}$ and a gain compression factor $\varepsilon$. By tracing the temporal evolution of carrier density, photon density, and material gain during gain switching, distinctly different effects of $g_{\text{s}}$, $\varepsilon$, and cavity lifetime $\tau_{\text{p}}$ on pulse generation were clarified. |
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| Bibliography: | Log plots of waveforms of output optical pulses, for (a) $g_{\text{s}}$ varied from 900 cm -1 to infinite, $g_{0} = 3.0 \times 10^{-9}$ cm, and $\varepsilon = 0$, (b) $g_{0}$ varied from 2.0 to $15.0 \times 10^{-9}$ cm, $g_{\text{s}} = 1100$ cm -1 , and $\varepsilon = 0$, (c) $\varepsilon$ varied from 0 to $0.6 \times 10^{-12}$ cm -2 , $g_{0} = 3.0 \times 10^{-9}$ cm, and $g_{\text{s}} = 1100$ cm -1 . The insert in (b) shows the corresponding gain curves. (a) Typical evolution of carrier density, material gain, and photon density (linear plot and log plot) during a cycle of pulse generation after a 2-ps optical pulse pumping, parameters $g_{0} = 3.0 \times 10^{-9}$ cm, $g_{\text{s}} = 1100$ cm -1 , and $\varepsilon = 0.2 \times 10^{-12}$ cm -2 were used for simulation. (b) Replots of material gain and photon density against carrier density. The four dashed arrows indicate the temporal evolution directions of material gain and photon density. According to the different temporal effects of $\varepsilon$ and $g_{\text{s}}$ on material gain and photon density, carrier density is divided into four regions. The photon-density evolutions of each region in (b) are correspondingly indicated in the time region in (a). |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.51.098001 |