Wavelength Conversion of Incoherent Broadband Sources by Intracavity Difference Frequency Mixing

We demonstrate a broadband wavelength converting system for incoherent amplified spontaneous emission (ASE) sources. It is based on single-pass difference frequency generation using a periodically poled stoichiometric lithium tantalate crystal placed inside the cavity of a tuneable self-injection-locked diode-pumped Cr
³⁺
:LiCAF laser. A spectral bandwidth of ~ 30 nm around 1550 nm is converted within a tuneable shift of ~ 12 nm. The technique we propose does not only provide ASE sources in new spectral allocations but it also opens up a way to perform spectral shaping.