title: Cell damage in near-infrared multimode optical traps as a result of multiphoton absorption.
abstract: We report on cell damage of single cells confined in continuous-wave (cw), near-infrared (NIR) multimode optical traps as a result of multiphoton absorption phenomena. Trapping beams at NIR wavelengths less than 800 nm are capable of damaging cells through a two-photon absorption process. Cell damage is more pronounced in multimode cw traps compared with single-frequency true cw NIR traps because of transient power enhancement by longitudinal mode beating. Partial mode locking in tunable cw Ti:sapphire lasers used as trapping beam sources can produce unstable subnanosecond pulses at certain wavelengths that amplify multiphoton absorption effects significantly. We recommend the use of single-frequency long-wavelength NIR trapping beams for optical micromanipulation of vital cells.
authors.forename: K
authors.initials: K
authors.lastname: König
authors.forename: H
authors.initials: H
authors.lastname: Liang
authors.forename: M W
authors.initials: MW
authors.lastname: Berns
authors.forename: B J
authors.initials: BJ
authors.lastname: Tromberg