研究了光学变条长实验中条的宽度对半导体激光器光增益测量的影响,提出利用光刻溅射处理样品来严格控制泵浦条的宽度，并详细研究了泵浦条宽度与样品增益及饱和长度关系。实验表明：泵浦条宽度越窄，饱和长度越长，但测得的增益系数有所减小。本文利用非平衡载流子扩散模型对此现象进行了解释。

In this paper, a method strictly controlling the width of pump stripe in the measurement of variable stripe length (VSL) method is present. For the gain measurements, we deal samples with lithography and sputtering, so that three different wide stripes, 2.6, 6.2 and 10.5 μm, are exposed separately on three samples, besides the rest parts are covered by 100 nm thick aluminum coating to strictly control the width of the pump stripe. We specially noticed that the pump stripes exposed are all along the same crystal orientation, in order to avoid the influence of different crystal orientation on optical gain. Using the VSL method, we studied the optical gain and saturation semiconductor laser with different pump stripe width. The gain spectra were discussed for three different pump stripe widths of 2.6, 6.2 and 10.5 μm, respectively. An increase of the modal gain and the decrease of saturation length with increasing stripe width were observed for most wavelengths on the amplified spontaneous emission spectrum through our experiments. The phenomenon that the gain changes with the pump stripe width could be due to the carrier diffusion. The carrier diffusions impact on different width pump stripe was discussed by theoretical calculation. The conclusion indicated that diffusion leads to lower non-equilibrium carrier concentration in a narrower pump stripe, and the modal gain decreases. To obtain effective optical gain and the long saturation length, experiments in many papers suggested making the pump stripe as narrow as possible, but this approach did not take the impact of diffusion into account. Our experiments showed that the diffusion can not be ignored when the stripe is narrow. Based on our experiments and calculation, pump stripe width is an important parameter related to the optical gain in VSL. We can choose an appropriate width of the pump stripe according to the needs when measuring the optical gain and its spectrum through the variable stripe length method.