Biocurious is a weblog about biology, quantified.

(Frequency) Double or nothing?

by PhilipJ on 18 February 2008

Celebrating 50 years of the journal Physical Review Letters, the editors at PRL have begun collecting hightlights of the past 50 years. They’re only a few years into things, but there’s already a paper that caught my eye: Generation of Optical Harmonics by Franken et al., PRL 7, 118 (1961) (link, seemingly freely accessible).

Shortly after the invention of the ruby laser (and before that the maser), it was discovered that a harmonic of the laser’s natural frequency was being emitted from dielectrics when incident beam was sufficiently intense. This has become a commonly used property, in that many of the lasers today (particularly emitting in the green, like YAG lasers) all use frequency doubling to produce visible output, as the diodes naturally output in the near IR.

To find out how it works, I recommend reading the paper, but I suspect you might not be convinced. Here’s why:



No doubled light as far as I can tell! Maybe they didn’t have peer review back in those days.

(I actually suspect it is the manner in which the digital copies were created. I’m going to check the library’s paper copy tomorrow.)



  1. J. Simonen    3322 days ago    #

    By coincidence I just heard this story last Friday. It was told by a scientist who remembered the time when the paper got out. Also, I learned that the story is told by a professor of non-linear optics in his lectures every year at my University.

    So what is the story? The version they tell here is that the editors of PRL thought that the frequency doubled emission was just some speck of dirt in the picture, so they removed it. It shouldn’t be present in the paper copy either…


  2. sam    3322 days ago    #

    wow. i really hope that story is true, J. Simonen.

    i like that they call the laser an “optical maser.” ha!


  3. PhilipJ    3321 days ago    #

    J. Simonen – that’s hilarious! I forgot to visit the library today, so I’ll have to update everyone tomorrow.


  4. sam    3321 days ago    #

    it’s not in the original. either the editors removed it, or it didn’t copy well from the original plate. hilarious.


  5. Michelle    3317 days ago    #

    Great info


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