Abstract
We report the ultrashort-pulse Cr:ZnS laser mode-locked by graphene-based saturable absorber mirror. Using the combination of bulk material and a chirped mirror, we demonstrate the shortest reported so far mid-IR pulses of only 5.1 optical cycles (41 fs) centered at 2.4 µm with 190 nm spectral bandwidth. The pulse spectrum almost completely fills the water-free atmospheric window. The output parameters reach 2.3 nJ pulse energy and 250 mW average output power at 108 MHz repetition rate.
Highlights
In the recent years, graphene has become a most sought-after saturable absorber for passive mode-locking of lasers
The pulse duration of around 50 fs and spectral bandwidth over 120 nm FWHM were reached near the pulse breakup limit
The pulse spectrum was centered at 2.37 μm where the calculated intracavity group-delay dispersion is about 400 fs2
Summary
Graphene has become a most sought-after saturable absorber for passive mode-locking of lasers. In practice the absorption may differ from the theoretical value when graphene is doped, or forms bi-, tri- etc. Successful graphene-based femtosecond lasers have been demonstrated for virtually every configuration and in various spectral regions (a recent review can be found in [4], and new results keep arriving almost on a monthly basis). Practical implementations of graphene saturable absorbers (GSA) can take different forms, but for solid-state lasers with sizeable mode diameters, a CVD-based process [5] proved to be quite convenient. A Cr:ZnS laser with this kind of GSA produces up to 250 mW of the shortest to-date generated pulses of 41 fs at 2.4 μm central wavelength
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
