Lightpulse

Lightpulse refers to a short-duration burst of electromagnetic radiation produced by a pulsed light source or laser. Typical durations range from femtoseconds (10^-15 s) to nanoseconds (10^-9 s). Wavelengths span ultraviolet to infrared, with spectral content tied to pulse duration due to Fourier limit.

Production and measurement: Mode-locked lasers generate extremely short pulses by phase locking of longitudinal modes, while Q-switched and gain-switched lasers produce longer nanosecond pulses. Pulse shaping can tailor temporal profile and chirp. Pulse energy and peak power vary from microjoules to millijoules. Diagnostics include autocorrelators, streak cameras, fast photodiodes, and frequency-resolved optical gating.

Applications: Lightpulses enable high-speed optical communications, allowing high bit-rate transmission. They are used in time-resolved spectroscopy and pump-probe experiments to study fast dynamics in materials and chemical processes. In manufacturing, ultrashort pulses enable precise micromachining and surface modification. In biomedical imaging, lightpulses underpin techniques such as two-photon excitation and other nonlinear modalities.

Physical considerations: Pulses broaden as they propagate due to group-velocity dispersion, particularly in fibers, which requires dispersion management or compensation. Nonlinear effects such as self-phase modulation and cross-phase modulation can modify the pulse spectrum and shape at high intensities. Coherence and phase stability are important for applications relying on interference or precise timing.

Etymology and variants: The term lightpulse is used informally in some contexts; more common terms include optical pulse and ultrashort pulse. Distinctions are made among femtosecond, picosecond, and nanosecond pulses based on duration and spectral characteristics.