800nm Chirped Mirror BS1631-25.4-1

Overview

The 800nm Chirped Mirror 0fs² (BS1631-25.4-1) from Ultrafast Innovations is a specialized 50:50 polarizing beam splitter designed for ultrafast Ti:Sapphire laser systems operating at 800 nm center wavelength with broadband coverage from 500–1050 nm. This mirror delivers zero group delay dispersion (0 fs² GDD per bounce) at 45° angle of incidence for P-polarized light, making it ideal for splitting sub-10 femtosecond pulses without introducing temporal broadening.

Unlike standard chirped mirrors that compensate for positive or negative dispersion, this 0 fs² GDD design maintains pulse fidelity in low-dispersion optical paths where spectral phase manipulation is handled elsewhere in the system. The flat GDD response across the 500–1050 nm range ensures minimal pulse distortion for few-cycle pulses, making it essential for applications requiring precise beam splitting without altering temporal characteristics in CPA systems, OPCPAs, and ultra-broadband Ti:Sapphire oscillators.

Applications

• Ti:Sapphire CPA system beam splitting: Divide amplified pulses between pump and probe arms while preserving sub-20 fs pulse duration
• OPA and OPCPA pump-signal separation: Route 800 nm pump beams at 50% reflectance without introducing GVD into parametric amplification stages
• Multi-branch ultrafast spectroscopy: Split broadband supercontinuum or few-cycle pulses for pump-probe, transient absorption, or HHG experiments
• Dispersion-neutral interferometry: Enable balanced Mach-Zehnder or Michelson configurations for ultrafast metrology without temporal walk-off

Construction & Performance

Manufactured on a 25.4 mm diameter, 1.0 mm thick UVFS substrate, this P-polarized beam splitter features an ion beam sputtered (IBS) multilayer dielectric coating optimized for 45° AOI. The coating delivers R>50% reflectance across the full 500–1050 nm bandwidth with a laser-induced damage threshold of 0.2 J/cm² for femtosecond pulses. The precision-polished UVFS substrate ensures wavefront quality suitable for demanding ultrafast laser applications including chirped pulse amplification and optical parametric generation.

Storage & Handling

Operate at 25 °C, 40–60% RH. Clean only with >99% optical-grade ethanol and lint-free lens tissue using single-pass drag method. Avoid abrasive cloths and water.