Mode-Locked Laser
Mode-locked laser: cavity length for a repetition rate, transform-limited bandwidth of a sech² or Gaussian pulse, number of locked modes, pulse energy and peak power.
Cavity length (optical)
1.874 m
pulse period 12.50 ns
Transform-limited bandwidth
25.23 nm
Δν = 0.3148/τ = 3.148 THz
Locked modes in the FWHM
3.935e4
Δν/f_rep; 19.3 optical cycles in the pulse
Peak power
11.02 kW
E = P/f = 1.250 nJ; duty 0.0008000 %
The pulse train repeats once per cavity round trip, f_rep = c/2L (linear) or c/L (ring), with L the optical length. A transform-limited pulse of intensity FWHM τ spans Δν = K/τ, K = 0.4413 (Gaussian) or 0.3148 (sech²), so about Δν/f_rep modes oscillate in phase. A chirped pulse is longer than this limit for the same bandwidth. Peak power: 0.939 E/τ (Gaussian), 0.881 E/τ (sech²).
Single pulse
- Intensity
Model and references
Textbook approximation. A standard approximation from the literature (for example paraxial, plane-wave or Gaussian-beam), valid within the range the page states. About the tiers
Transform-limited pulses: Δν·τ = 0.4413 (Gaussian) or 0.3148 (sech²), intensity FWHMs. The mode count is the number of modes f_rep apart inside Δν. Peak power from the shape factor, energy P/f_rep. Chirp, pedestals and the mode-locking mechanism itself are not modelled.
- Haus H. A. (2000). Mode-locking of lasers. IEEE J. Sel. Top. Quantum Electron. 6, 1173–1185. doi:10.1109/2944.902165
- Diels J.-C., Rudolph W. (2006). Ultrashort Laser Pulse Phenomena, 2nd ed., ch. 1. Academic Press.