| Abstract: | Ultrashort laser pulses that combine high peak power with low intensity noise are essential for applications such as high-order harmonic generation, timing synchronization, and precision metrology. The recently developed gain-managed nonlinear (GMN) amplification scheme has emerged as an attractive approach for such applications due to its simple architecture and strong performance. Despite its rapid adoption, the noise characteristics of GMN amplifiers remain largely unexplored.
In this seminar, I will present a comprehensive experimental and theoretical study of the evolution of relative intensity noise (RIN) in a standard Yb-doped fiber GMN amplifier. We demonstrate the generation of high-energy (~80 nJ), sub-40 fs pulses with 26.5 dB of gain and up to twelvefold spectral broadening. In contrast to the behavior typically observed in nonlinear amplifiers, we find that the intensity noise in GMNA decreases with increasing gain and nonlinearity, reaching an integrated RIN of 0.38%, below the 0.42% noise level of the seed source.
We further investigate the spectral distribution of the noise and observe a non-uniform, U-shaped profile in which the RIN of the full spectrum is lower than that of individual spectral slices, indicating the presence of intrinsic spectral correlations. Finally, I will discuss a rate-equation-based theoretical model that captures these trends and shows that the amplifier effectively acts as a high-pass filter for seed fluctuations, enabling noise suppression when pump and seed noise contributions are comparable. Together, these results position GMNA as a promising platform for ץprecision applications requiring low-noise, high-energy ultrafast laser pulses |