Yes, some care has to be taken so that the supported bandwidth of the steering mirrors is larger than the spectral width of the oscillator. Typically, coated silver mirrors should be used as standard dielectric mirrors may not be broadband enough. Also, (dielectric) multistack mirrors may spoil the phase of the pulse, as they may introduce phase jumps in the spectral regions where the stacks join, which will destroy the compressibility of the pulse, i.e. the short pulse duration. Related to: venteon
