The dynamic gain of a few-mode erbium-doped fiber amplifier (FM-EDFA) is vital for the long-haul mode division multiplexing (MDM) transmission. Here, we investigate the mode-dependent dynamic gain of an FM-EDFA under various manipulations of the pump mode. First, we numerically calculate the gain variation with respect to the input signal power, where a mode-dependent saturation input power occurs under different pump modes. Even under the fixed intensity profile of the pump laser, the saturation input power of each spatial mode is different. Moreover, high-order mode pumping leads to a compression of the linear amplification region, even though it is beneficial for the mitigation of the differential modal gain (DMG) arising in all guided modes. Then, we develop an all-fiber 3-mode EDFA, where the fundamental mode of the pump laser can be efficiently converted to the LP₁₁ mode using the all-fiber mode-selective coupler (MSC). In comparison with the traditional LP₀₁ pumping scheme, the DMG at 1550 nm can be mitigated from 1.61 dB to 0.97 dB under the LP₁₁ mode pumping, while both an average gain of 19.93 dB and a DMG of less than 1 dB can be achieved from 1530 nm to 1560 nm. However, the corresponding signal input saturation powers are reduced by 0.3 dB for the LP₀₁ mode and 1.6 dB for the LP₁₁ mode, respectively. Both theoretical and experimental results indicate that a trade-off occurs between the DMG mitigation and the extension of the linear amplification range when the intensity profile of pump laser is manipulated.

针对传统压电惯性驱动器普遍存在的回退问题，创造性地提出双振子反向连接的接线方式，在此基础上设计了一种惯性压电直线驱动器。基于这种接线方式，可以使驱动器工作在“前进-前进”运动模式，从原理上彻底消除回退现象。首先，为了更好地理解驱动器的运动特性，深入分析了反接条件下的驱动器的运动原理并初步建立了理论模型。接下来，本文设计并制作了试验样机，搭建了试验系统，进行了一系列试验探究该驱动器在正接（传统的接线方式）、反接（所提出的接线方式）两种接线方式下的运动性能。此外，为了评估驱动器的应用价值，利用斑马鱼胚胎进行了细胞药物注射模拟实验。试验结果表明：相较于“前进-回退”的运动模式，在“前进-前进”的运动模式下，驱动器可以实现无回退，能量转换效率从2.16%提高至2.60%，运动速度从6.08 µm/s增大至7.88 µm/s，最大偏差为0.12 µm，标准偏差为0.035 6。所设计的驱动器具有较高的稳定性和能量转换效率，并且完全解决了回退问题，有望用于细胞操作和微电极植入等领域。