Talk:Liquid-crystal laser

new sources

I found some new sources, but I am not sure they could be used in this article, so instead of adding the info directly to the article, I'd better post it here:

• "Figures 5(a)–5(f) show the obtained color-changeable lasing patterns (from green to deep red) on the screen, as well as the corresponding lasing wavelengths (from 553 to 687nm) as the pumping position of the cell is varied from x = 6 to x = 34 mm. Hence, a large spatially tunable range of asing wavelengths with a width of 134nm in a length of 28mm on the cell,based on the AzoM-added DDCLC laser with a UV-induced pitch gradient, can be obtained."
• "Unlike most conventional semiconductor lasers, the emission wavelength of a liquid crystal laser can be dynamically tuned using an applied voltage to alter the degree of periodicity of the macroscopic molecular structure."
• "When illuminated at 430 nm by the pump source, the RGB liquid-crystal cell produces monochromatic laser emission at 617, 534, and 470 nm, depending on whether the cell contains the red, green, or blue chiral formulation. If the source illuminates a gradient cell that contains two or more liquid-crystal dye formulations, a variety of lasing colors can be observed at the output. Such gradient cells can be readily fixed as soft gels using cross-linkable polymers."
• "NONLINEAR OPTICAL RESPONSE OF CYANOBIPHENYL lIQUID CRYSTALS TO HIGH-POWER,NANOSECOND LASER RADIATION"
• "liquid crystal (CLC) laser pumped by second harmonic Nd-YAG laser is demonstrated" It is a google search result (The provided quote was taken from the first item in the search)

--Mbz1 (talk) 04:02, 27 April 2011 (UTC)

Questions

The questions below are copied from the talk page. I believe they should be here too:

• Ok, it is a laser, so what is the active element: define materials, what wavelength does it emit; CW, pulsed or both (whatever the pumping source emits?), typical intensity?
  • It emits both CW and pulsed
  • A typical intensity is shown in the figure #3
  • The sctive materials are: "a fluorescent dye and a cholesteric liquid crystal"

--Mbz1 (talk) 16:32, 28 April 2011 (UTC)

• "electrical pumping system"? Electroluminescence in the liquid crystal?
  • "Furthermore, investigations into the use of more practical pumping solutions (eg: inchoerent optical pumping, or electrical pumping) are also under way, with the intention of developing the technology into a commercially more useful device."--Mbz1 (talk) 17:36, 28 April 2011 (UTC)
• The article says LCL provides the continuous wide spectrum tunability of dye lasers. Tunability how? External (grating) or internal (acting on the active medium)? What kind of resonator does it have?
  • internal

--Mbz1 (talk) 16:46, 28 April 2011 (UTC)

• "Self-organization at length scales corresponding to visible light" - dubious - add actual size.
• History section: "predicted theoretically in cholesteric"? "achieved experimentally" in what?
  • "First experimental observation of lasing action in CLCs and a number of follow-up experiments were performed by Il'chishin et al. in 1980"--Mbz1 (talk) 20:30, 28 April 2011 (UTC)
• The title of section "Theory" seems misleading to me because it seems to be on mechanism/operation with no actual theory.
• "Nonlinear response" is way too general, especially when followed by a specific value (so many types of nonlinearities).
  • "We report the experimental evidence of a nonlinear optical response among the highest ever observed. A nonlinear refractive index on the order of 103 cm2/W (that is 108 times higher than in Giant Optical Nonlinearity) has been obtained in randomly oriented thin liquid crystal cells. This result shows the fundamental role played by the surface in the nonlinear optical response of dye-doped liquid crystals."--Mbz1 (talk) 19:58, 28 April 2011 (UTC)
• "Pure wavelength" - you mean monochromatic wavelength? (it is in the hook, but nowhere explained in the article).
  • There was an alternative hook that is supprted by online source--Mbz1 (talk) 20:17, 28 April 2011 (UTC)
• I can't imagine a display screen with a laser-pumped laser - seems too complex.
  • "Laser emission from a dye-doped cholesteric liquid crystal pumped by another cholesteric liquid crystal laser"--Mbz1 (talk) 19:45, 28 April 2011 (UTC)

Materialscientist (talk) 08:06, 26 April 2011 (UTC)

• Present wording left me wondering if this is something that has been built or just a concept. Should be explicit. LeadSongDog come howl! 06:57, 29 April 2011 (UTC)

 Fixed

"Electrical pumping" just means using an electric field to achieve population inversion instead of exciting the electrons with light. It is common in excimer lasers (strip away an electron from argon, and it becomes willing to bind metastably with fluorine, for instance), though I am not sure how much it is used for other types. Clearly this should be clarified. - 2/0 (cont.) 13:23, 29 April 2011 (UTC)

You need significant electron conductivity so that electrons can be accelerated by the field and transfer energy to the active medium. This is easy in gases and crystals. I was wondering how is it possible in liquid crystals (which are poor conductors). Materialscientist (talk) 13:30, 29 April 2011 (UTC)

"Self organization" is in contrast to building a layered metamaterial (added to lead now, but could probably stand to be clarified) - the liquid crystal is chosen with a structure corresponding to the desired wavelength.

They have been built, but so far as I know not on an industrial scale. The Mechanism section (better fit with the material than Theory, thanks; I started writing that as a real theory section, but found myself digressing too much into stuff that belongs at Photonic crystal) should present it as well-established, but the Applications section should be all speculative. - 2/0 (cont.) 13:23, 29 April 2011 (UTC)

• If I understand correctly, an LCL is any laser using fluorescent loaded LC as the lasing medium. Hence the article could encompass not just one but a whole class of constructions with different cavities, tuning mechanisms, modulation schemes, gating, and so forth. LeadSongDog come howl! 13:38, 29 April 2011 (UTC)