Titanium:Sapphire Femtosecond Pump Mirrors Optimized for Negative GDD
REO Ultrafast Pump Optics
January 21, 2013
REO, a leading manufacturer of high volume precision optical solutions, has introduced an expanded series of ultrafast dichroic
pump mirrors designed to support cutting edge performance in femtosecond titanium:sapphire (Ti:S) lasers. This is achieved through
the use of thin film coatings that generate negative group delay dispersion (GDD) to compensate for positive GDD caused by other
These focusing (concave) optics provide broadband performance, delivering >99.7% reflectivity over the entire 675 – 1100 nm
wavelength range, while also providing high (>98%) transmission at the 532 nm pump wavelength. This broadband reflectivity
makes these optics ideal for use in virtually any Ti:S oscillator, particularly one-box models. Examples include broadband
(very short pulse) oscillators, widely tunable oscillators for microscopy and spectroscopy, and fixed wavelength oscillators
for seeding ultrafast amplifiers.
Even if it produces broadband output, a high performance femtosecond laser oscillator’s pulsewidth is often limited by the
positive GDD, caused principally by the transmissive optics in the laser cavity, including the Ti:S crystal itself.
This can be partially offset by the use of reflective cavity optics with negative GDD. These enhanced pump mirrors from
REO typically deliver up to 100 fs² of negative GDD. In addition they are designed for minimum Third Order Dispersion (TOD)
to further simplify the laser designer’s task of achieving the shortest possible transform-limited pulsewidth.
These spherical mirrors are offered with a radius of curvature of 10 cm, 15 cm or 50 cm, with flats and other radius values
available upon request. Standard diameters are 7.75 mm (0.3 in.), 12.75 mm (0.5 in.) and 19 mm (0.75 in.).
REO produces high precision thin film coatings, optics and opto-mechanical assemblies for the ultraviolet,
visible and infrared. Located in Boulder, CO, the company primarily services medium to high volume OEMs including
manufacturers of defense and aerospace systems, laser systems, semiconductor tools, medical systems, life sciences
instrumentation and telecom equipment. REO is a privately held company.
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