Talk:Nitrogen laser

Comments

Can some one please help me with the not so easy to find facts about metastable Nitrogen and ion concentration! There are so many nice Nitrogen-Laser websites out there. Maybe someone can donate a photo? Our Laser doesn't work so well :-( --Arnero 09:20, 4 December 2005 (UTC)

Not clear

In my opinion the sentence " The nitrogen laser is a 3-level laser. In contrast to a ruby laser or to other more typical 4-level lasers, the upper laser level of nitrogen is directly pumped, imposing no speed limits on the pump. Pumping is normally provided by direct electron impact; the electrons must .."is confusinal beacuse ruby laser is a 3 level laser, I have had some heartbeat reading it, i thought all i've studied was injust —Preceding unsigned comment added by Franz as tux (talk • contribs) 13:36, 7 June 2010 (UTC)

Superluminescence?

I added a "dubious" tag to the claim that nitrogen lasers "more often operate on superluminescence alone". I think there is some confusion here between superluminescence and self-lasing. A high-gain system, especially one where the gain medium is large in diameter, will "find" an optical cavity between any two even slightly reflective objects in the vicinity of the beam path. With a high gain TEA optical amplifier, one has to do some work to make it not lase. This is not superluminescence. There is an optical cavity, it is just not an intentionally-created cavity.

If a gain medium had such high gain that it could produce significant emission on its own via superluminescence, then it will automatically go into true lasing if there are any two perpendicular surfaces in the vicinity of the axis of the device. If you have high enough gain, a piece of white paper (or a piece of black plastic, or a transparent window) is a perfectly good cavity end mirror. --Srleffler (talk) 03:14, 8 May 2012 (UTC)

I don't understand your point. The nitrogen laser doesn't need reflective surfaces to work and due to the low life time of the excited states, it can't profit a lot from such reflective surfaces (a resonator).

The beam "travels" in the direction of the cavity, because this direction has the highest gain (simply by being the longest path available), spontaneous emission starting in any other direction will experience less amplification before it leaves the cavity. My problem here is that I have no idea what "self-lasing" means in all its details, and whether superluminescence describes what is going on in a nitrogen laser accurately. In German we have the term "Superstrahler" to describe a laser that works with amplified spontaneous emission, without the need for a resonator. It is not the same as superluminescence, but it seems to be an application of it, at least I don't see any notable differences right now. Gerald Jarosch (talk) 00:34, 7 January 2013 (UTC)

I was distinguishing between pure superluminescence, with no optical feedback, and the lasing that occurs in a high-gain medium in the presence of very weak optical feedback. I haven't worked with nitrogen lasers, but I have some experience with large carbon dioxide laser systems that use high power TEA amplifiers. In these systems, it is important to prevent the amplifiers from lasing on their own. This turns out to be relatively difficult. Because of the long optical path and high gain, stray reflection off of any surface that is perpendicular to a straight-line path through the cavity will cause lasing, which depletes the amplifier's gain. I had assumed that the situation would be similar in a nitrogen laser. I may, however, have underestimated the impact of the bottlenecking of the lower laser level. If it's true as stated in the article that the gain is depleted within 20 ns, then I agree that unless the laser is quite short external feedback will have a limited role.--Srleffler (talk) 03:38, 7 January 2013 (UTC)

The life time of the upper level is around 40ns without any interactions, at atmospheric pressure and in the presence of oxygen, this time goes down in the single digit ns range. The lower level is meta stable with a life time in the us range. So it can only squeeze one very short pulse out and then needs considerable time to cool down.

And, the N2-laser doesn't need any such feedback at all. If you take the typical home-built TEA-configuration that runs with air at atmospheric pressure, it will emit a laser pulse without any mirrors, or even a glass plate with the minimal 4% reflection or anything else. It will however emit half its energy on each side. That's the reason why there is usually a mirror on one side, to double the output on the other end. The mirror also increases the effective cavity length which leads to a better beam quality. Depending on cavity length (shorter cycle time) and pressure (excited states live longer) it may give an even better beam quality if you add an output coupler with very low reflectivity (I've never seen more than 8% used so far), so that the beam cycles a couple of times in the cavity. But this is not necessary for it to work.

So ... well, I'm still not an expert on the English language terms used to describe this phenomenon, but I'd say the article is correct. Gerald Jarosch (talk) 04:19, 7 January 2013 (UTC)

I removed the "dubious" tag, but left the "citation needed" one, because a citation would still be useful.--Srleffler (talk) 03:35, 8 January 2013 (UTC)

ruby laser is not a four level laser

The text is contradictory to the wikipedia entry of the ruby laser. — Preceding unsigned comment added by 128.176.12.234 (talk) 09:24, 21 August 2012 (UTC)

Yes, the text was wrong. I fixed it.--Srleffler (talk) 02:41, 22 August 2012 (UTC)

Visible Nitrogen spectral line

Isn't there a visible laser line for Nitrogen? — Charles Edwin Shipp (talk) 13:37, 27 February 2014 (UTC)

Reason I ask is because in 1969 I received the MA in Physics creating and demonstrating a 567.96 nm (yellow-green) laser line from a low-pressure high-voltage 65cm laser. The media was air. — Charles Edwin Shipp (talk) 22:49, 6 March 2014 (UTC)

commercial version

I noticed that the link to a commercial version was a dead Newport page. Tried retrieving the page using the Wayback machine but couldn't find it. So I linked a different commercial laser and updated the energy per pulse to suit.--Uhoj (talk) 02:37, 27 November 2018 (UTC)