How does Third-Harmonic-Generation affect laser linewidth?

Explanations of phase noise: https://opg.optica.org/oe/fulltext.cf... https://books.google.dk/books?id=iUld... IEEE definitions of phase noise, power spectra etc.: https://cwe.ccsds.org/sea/docs/SEA-TI... Autocorrelations and WKT: https://www.comm.utoronto.ca/~frank/n... https://www.ieee802.org/3/ae/public/a... https://www.unine.ch/files/live/sites... The log-normal distribution: https://en.wikipedia.org/wiki/Log-nor... Link to Python notebook used for simulation in this video: https://github.com/OleKrarup123/NLSE-... SHG increases phase noise power by 6dB (= factor of 4): https://hal.science/hal-02066183v1/do...