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An all-optical analog-to-digital conversion scheme based on a Sagnac loop and balanced receivers is proposed and experimentally demonstrated. Adjustable phase shift about the transfer function of the Sagnac loop is obtained by using the multiwavelength optical pulses to realize the phase-shift optical quantization. Benefit from the complementary outputs at the transmitted and reflected ports of the Sagnac loop and balanced receiver can be used to obtain the quantized output binary signal for the encoding operation. A proof-of-concept experiment is implemented using a wavelength tunable continuous-wave laser diode. Using 16 different wavelengths, the 16 quantization levels are demonstrated and an effective number of bits (ENOB) of 4 bits is obtained.

Electron acceleration in the plasma wakefield driven by asymmetric laser pulses is investigated analytically. It is found that the asymmetric laser pulse can significantly modify the phase portrait of the electron dynamics and enhance the maximum energy of the accelerated electrons. There exists an optimum ratio of the lengths of the rising and falling segments of the asymmetric laser-pulse. A linear scaling law relating the accelerated electrons' energy and the plasma density is obtained. This result differs from the power-law dependence often associated with symmetric laser pulses.

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