.NET Wrapper for the FFT in the Intel oneAPI Math Kernel Library (https://www.intel.com/content/www/us/en/developer/tools/oneapi/onemkl.html#gs.atk6us)
Take a look into the Test project to see how the wrapper and the FFT is used. Or take look into this project: https://github.com/TSerious/FFTBench, where you can compare the performance of different FFT implementations.
Documentation for the Intel oneAPI Math Kernel Library can be found here: https://www.intel.com/content/www/us/en/develop/documentation/get-started-with-mkl-for-dpcpp/top.html