Simulated supercontinuum generation in the human eye

Abstract

Femtosecond laser pulses of sufficiently high intensity are prone to undergo a number of nonlinear effects while propagating in media. The increasing use of high intensity, femtosecond laser systems underscores the need to understand the retinal hazards generated by nonlinear optical effects, like the generation of supercontinuum. Current laser safety standards such as ANSI Z136.1 for pulse wavelengths of 1200 nm - 1400 nm have been determined from experimental studies using pulse durations longer than 100 fs and linear pulse simulations. The combination of strong absorption, broad bandwidth, and dispersive effects makes standard nonlinear pulse simulation methods, based on the slowly varying envelope approximation, unsuitable for the study of near-infrared pulses in biological tissues. To model retinal hazards, we leverage an existing model for linear ultrafast pulse propagation that does not rely on an envelope approximation and simulate spectral broadening in water. Using one-dimensional simulations of the self-phase modulation, and incorporating the effect of self-focusing, we validate the model using previous experiments for white-light supercountinuum generation in water. We then simulate propagation of 10 fs - 1 ps, 1200 nm - 1400 nm pulses at the current ANSI MPE limit for pulses under 10 ps.Femtosecond laser pulses of sufficiently high intensity are prone to undergo a number of nonlinear effects while propagating in media. The increasing use of high intensity, femtosecond laser systems underscores the need to understand the retinal hazards generated by nonlinear optical effects, like the generation of supercontinuum. Current laser safety standards such as ANSI Z136.1 for pulse wavelengths of 1200 nm - 1400 nm have been determined from experimental studies using pulse durations longer than 100 fs and linear pulse simulations. The combination of strong absorption, broad bandwidth, and dispersive effects makes standard nonlinear pulse simulation methods, based on the slowly varying envelope approximation, unsuitable for the study of near-infrared pulses in biological tissues. To model retinal hazards, we leverage an existing model for linear ultrafast pulse propagation that does not rely on an envelope approximation and simulate spectral broadening in water. Using one-dimensional simulations of...