Dispersionless saturable absorber mirrors with large modulation depths and low saturation fluences

M. P. Lumb*, P. N. Stavrinou, E. M. Clarke, R. Murray, C. G. Leburn, C. Jappy, Nikolaus Klaus Metzger, C. T. A. Brown, W. Sibbett

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


We show that it is possible to eliminate group delay dispersion over wide bandwidths in low-finesse, resonant saturable absorber mirrors, whilst maintaining a low saturation fluence and a high modulation depth. By modelling the mirror structure we demonstrate that these properties can be produced by capping a resonant device with a single dielectric layer of carefully selected refractive index. We show that a specially capped dispersionless structure minimises the temporal broadening of femtosecond pulses reflected from the mirror. We compare this device against uncapped-resonant and anti-resonant structures. The superior performance of the capped, dispersionless device was verified experimentally by comparing resonant, anti-resonant and dispersionless quantum-dot (QD) saturable absorber mirrors incorporated into a Cr(4+):forsterite laser system. We found that a minimum pulse duration of 86 fs could be achieved for the dispersionless structure at 1290 nm with an output power of 55 mW compared to 122 fs in an anti-resonant structure and several-picosecond pulses for a resonant structure.

Original languageEnglish
Pages (from-to)53-60
Number of pages8
JournalApplied Physics B: Lasers and Optics
Issue number1
Publication statusPublished - Sept 2009


  • SESAMs
  • dielectric mirrors
  • passive-mode locking
  • femtosecond
  • solid state lasers
  • reflection
  • forsterite laser
  • ultrafast lasers


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