Ultra-broadband dispersive mirrors (PC, IR)

Our ultra-broadband compression mirror sets are available in many configurations. In particular for the near infrared spectral region we can realize up to 1.5 octaves of bandwidth covering wavelength range of 400-1200 nm. These mirror sets can be employed for pulse compression at chirped-pulse Ti:sapphire amplifier systems, for broadband oscillators and other applications. Customers have reached pulse durations as fast as 3 fs after spectral broadening in hollow-core fibers and gas cells with mirrors designed and manufactured by UltraFast Innovations. References and publications are available upon request.

The mirror GDD should compensate material (through which the initially short pulse passes) or the (nonlinear) pulse chirp so that the residual dispersion fluctuations are acceptably small in all of the relevant spectral range. Usually, during design optimization, residual fluctuations drop to a low level. The GDD fluctuations can broaden the pulse and lead to energy transfer from the initial single pulse to satellites. There are many design approaches which allow us to obtain GDD with low oscillations.
All possible design approaches are available at Ultrafast Innovations:

Complementary pair DM

Complementary mirror pairs were invented to overcome the fundamental problem of dispersion oscillations. Still, some residual ripples remain due to fluctuations in manufacturing. Using two different mirrors for which the GDD curves have the same oscillations and are shifted by only half a period, results in the lowest possible oscillations for the average GDD curve. For a pair of DMs covering less than 1 octave, such a design can be realized easily.

Double-angled DM (invented in 2009 by our colleague Dr. V. Pervak)

UltraFast Innovations now offers the next step in ultra-broadband chirped mirrors: double-angle dispersive mirror technology. In 2009 we suggested a novel concept for suppressing GDD oscillations in broadband wavelength range. It is based on identical DMs used in combination at two different angles of incidence. The “double-angle” DMs offer: i) Better manufacturing stability compared to the conventional complementary-pair approach; ii) reduced manufacturing costs compared to the complementary-pair approach, which requires two perfectly matched coating runs.
Double-angled mirrors with different production dates may be combined.

Brewster angle DM

Placing a DM at the Brewster angle for the top layer ensures only a small amount of Fresnel-reflected light, resulting in oscillation-free GDD. P-polarized light at large angles (the Brewster angle of fused silica is ~56°, for example) requires a significantly higher number of layers and greater total optical thickness. The Brewster angle DM can be used in an extra-cavity application where an angle of 55.6° is easily realized. Contrariwise, the intra-cavity beam bounces at a small incidence angle, which makes it unrealistic to use the Brewster-angle CM as a laser oscillator mirror.

For more detail about each approach see supplementary materials.

Many dispersive mirrors from UltraFast Innovations are available as double-angle optics. Please inquire as to whether your application can make use of this novel technology.

Please browse UFI’s design database for the following examples:

PC5, PC9, PC42, PC45, PC47, PC52, PC61, PC70, PC305

Applications

  • Pulse compression after spectral broadening in hollow-core fibers or gas cells
  • Cavity mirrors for ultra-broadband laser oscillators

Related Reading

  • T. Ganz et al. Optics Letters, Vol. 36, Issue 7, pp. 1107-1109 (2011)
  • V. Pervak et al. Opt. Express 17 7943 (2009) T. Nagy et al. Opt. Lett. 36, pp. 4422 (2011)
  • T. Witting et al. Opt. Lett. 36 1680 (2011)
  • I. Ahmad et al. Applied Physics B 97, 529 (2009)
  • S. Zherebtsov et al. Nature Physics 7, 656-662 (2011)
  • J. Rauschenberger et al. Laser Phys. Lett. 3 37 (2006)
  • J. Seres et al. Appl. Phys. B 82 513 (2006)

Please contact us for further information and references.