High‐order Stokes and anti‐Stokes Raman generation in monoisotopic CVD ¹²C‐diamond

We determined, for the first time, the room temperature phonon energy related to the F_2g vibration mode (ω_SRS(12C) ∼ 1333.2 cm^–1) in a mono‐crystalline single‐isotope CVD ¹²C‐diamond crystal by means of stimulated Raman scattering (SRS) spectroscopy. Picosecond one‐micron excitation using a Nd³⁺:Y₃Al₅O₁₂‐laser generates a nearly two‐octave spanning SRS frequency comb (∼12000 cm^–1) consisting of higher‐order Stokes and anti‐Stokes components. The spacing of the spectral lines was found to differ by Δω_SRS ∼ 0.9 cm^–1 from the comb spacing (ω_SRS(natC) ∼ 1332.3 cm^–1) when pumping a conventional CVD diamond crystal with a natural composition of the two stable carbon isotopes ¹²C (98.93%) and ¹³C (1.07%). (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)