Optimal selection of cut-on wavelength in soliton self-frequency shift for nonlinear optical microscopy

Abstract

Soliton self-frequency shift (SSFS) is a versatile technique for generating ultrashort optical pulses with customized wavelengths suitable for nonlinear optical microscopy. However, spectral overlapping of the soliton with the residual sometimes causes extra power deposition onto the biological samples, which may further induce optical damage. Consequently, how to choose the optimal optical filter is of vital importance for increasing signal level and minimizing damage. Here we propose maximizing the ratio between multi-photon signal and the nth power of the excitation pulse energy as a criterion for optimal spectral filtering in SSFS. This optimization is based on most efficient signal generation and entirely depends on physical quantities that can be easily measured experimentally.