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

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 - Sep 2009


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


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