Talk:Laser linewidth

How is a mention or reference to the Schawlow-Townes linewidth, as well as its corrections, the Petermann factor, the Henry-alpha factor, the bad cavity factor (first found by Woerdman and coauthors) not mentioned here? Acerjan 15:04, 16 May 2014 (UTC)

I think there should be a better discussion of how GHz and kHz relates to the linewidth in nm.

Is there a reason why, in the formula in section "Pulsed lasers", we have both a \theta and \Theta? If this is normal, can someone define the difference? Etienne.raymond (talk) 22:30, 16 December 2014 (UTC)

Definition? Description? Vague hand-waving?
I read the article twice and if there was any attempt to say what laser linewidth is, I failed to spot it. It can be measured in GHz and also in Nm, and I could tell you a couple of technologies that can be used to measure it, but that's about all I've got.

Can someone add a brief description of laser linewidth for a broader audience? — Preceding unsigned comment added by Eshafto (talk • contribs) 14:46, 13 April 2016 (UTC)

The intro cleverly defines the Laser linewidth as the linewidth of a laser.

If you are looking for a working definition of what linewidth is a measure of this page does not have it. — Preceding unsigned comment added by 134.24.149.212 (talk) 18:45, 13 March 2017 (UTC)

Spectral domain brought up in context of differentiation of Wavelength vs Frequency
It seems misleading to replace the statement “wavelength domain” from the book cited, with “spectral domain” in the section header. Spectral domain seem to relate in a similar way to both frequency and wavelength, and is not giving the differentiation needed within “spectral domain”. The two formulas are both spectral domain, while one is relating to frequency units while the other to wavelength units. See: Wikipedia spectrum: The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. Przemek108 (talk) 10:09, 7 January 2020 (UTC)

New insight added
Many aspects of the laser linewidth have remained unclear in the past. Many different and partially contradicting versions of the laser linewidth have been published in the literature over the decades, particularly in the 1960s. The believe that the laser linewidth can only be understood in a full quantum-electrodynamics approach has found strong support, not surprisingly especially within the quantum-optics community. Hardly any textbook on lasers or general optics has dared to deal with the laser linewidth in a manner accessible even to experts and graduate students. Our very recent work has made it clear that the original Schawlow-Townes equation is based on a semi-classical derivation and has now been proven to be a four-fold approximation of a more fundamental linewidth equation, which describes the laser as an amplifier of spontaneous emission that operates at a point where the gain is smaller than the losses. No quantum fluctuations or other quantum-optical ingredients are required to understand this most fundamental part of the laser linewidth. However, this does by no means exclude that quantum fluctuations or other quantum-optical phenomena or even other semi-classical phenomena modify this fundamental laser linewidth, and potential examples are given at the end of the theory part. At least the physics underlying the fundamental laser linewidth and its four-fold approximation, the original Schawlow-Townes equation, has been clarified in the theory part of this article. More scientific work needs to be done to further clarify the situation. Pollnau (talk) 05:25, 13 March 2020 (UCT)