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Thread: White light monolithic semiconductor laser

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    Default White light monolithic semiconductor laser

    http://www.nature.com/nnano/journal/....2015.149.html

    I just want to see what's going to come our way in a few years..
    484, 530, 642 and 675 to name a few out of one semiconductor laser.
    Nano technology is going to play nice with light...

    Fred.

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    Quote Originally Posted by infredible View Post
    http://www.nature.com/nnano/journal/....2015.149.html

    I just want to see what's going to come our way in a few years..
    484, 530, 642 and 675 to name a few out of one semiconductor laser.
    Nano technology is going to play nice with light...

    Fred.
    reviewer one notes:
    This is not a direct injection laser running off DC . This was pumped by 355 nm from Tripled pulsed ND:YAG.
    Steve
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    Default



    Click image for larger version. 

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ID:	47970 Why pulsed? heat
    Cheers

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    Steve,
    They brag about world's first white light laser.
    I don't see any mention of a pump soucre in that short snippet. What would be the point, this has been done before.
    Monolithic semiconductor nano laser sounds to me that this indeed a self contained laser source. This article mention DC.
    http://phys.org/news/2015-07-world-white-lasers.html

    Fred.

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    Quote Originally Posted by infredible View Post
    Steve,
    They brag about world's first white light laser.
    I don't see any mention of a pump soucre in that short snippet. What would be the point, this has been done before.
    Monolithic semiconductor nano laser sounds to me that this indeed a self contained laser source. This article mention DC.
    http://phys.org/news/2015-07-world-white-lasers.html

    Fred.
    They pump the three different regions independently for color control with seven colors (just like TTL)

    Interesting about direct injection , because the cited paper does not cover it:

    I Quote Nature e Nanotechnology Year published2015) DOI:doi:10.1038/nnano.2015.149

    QUOTE:

    Optical measurements

    Samples were first cleaved from as-grown pieces by the bend-to-fracture method43. High-quality end facets were thus created as partially reflective mirrors to define the laser cavities. All optical measurements were performed at room temperature. After the fracture, samples were then transferred individually onto MgF2 substrates (refractive index of ∼1.38) for enhanced optical confinement using a homemade tapered fibre. In the single-beam uniform pumping experiment (schematically shown in Supplementary Fig. 11a) for the multi-colour lasing shown in Figs 3 and  4, the third harmonic of a Q-switched Nd: YAG laser (Spectra Physics) was used to uniformly pump the individual samples (λ = 355 nm, repetition rate of 10 Hz, pulse width of 9 ns) at an angle of 15 from the sample normal, with a spot size of 180 m. The resulting emission was collected through a dark-field objective lens (Olympus LMPlanLF 50, numerical aperture of 0.5) at an angle of 45 from the sample normal to enhance the collection efficiency of stimulated emission and reduce the spontaneous emission background. The collected light was then directed though a beamsplitter and gathered simultaneously by a charge-coupled device (CCD) camera (Lumenera Infinity 2-1R) and monochromator (Triax 320) equipped with a Si array detector (Jobin Yvon CCD). A long-wavelength-pass 405 filter (Semrock EdgeBasic) was used to remove the pump laser wavelength from the collected spectra. In the lasing colour tuning and mixing experiments shown in Figs 5 and 6, the third harmonic of a Q-switched Nd:YLF laser (Spectra Physics, λ = 349 nm, repetition rate of 10 Hz, pulse width of 5 ns) was used to provide better pulse-to-pulse stability. Details of the set-up are shown in Supplementary Fig. 11b. The laser was first directed through a set of cylindrical lenses to change the length-to-width ratio of the laser spot. After splitting into three separate beams, each beam was then directed through three independent polarizer and analyser set-ups and focused to a 260 m  5 m narrow stripe-like spot parallel to the cavity


    End Quote

    Steve
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    Lightbulb

    Quote Originally Posted by infredible View Post
    ...This article mention DC...
    ..Yessir, but did you read what was written about the 'DC'?..

    "While this first proof of concept is important, significant obstacles remain to make such white lasers applicable for real-life lighting or display applications. One of crucial next steps is to achieve the similar white lasers under the drive of a battery. For the present demonstration, the researchers had to use a laser light to pump electrons to emit light. This experimental effort demonstrates the key first material requirement and will lay the groundwork for the eventual white lasers under electrical operation."

    ..Bada bing, it's an OPSL.. They even showed that in the 'comp'.. http://cdn.phys.org/newman/csz/news/...uresearche.jpg

    ..And, someone *coff coff* The Writer *coff coff* needs to do Her homework a bit more, too..

    "While lasers were invented in 1960 and are commonly used in many applications, one characteristic of the technology has proven unattainable. No one has been able to create a laser that beams white light."

    ..Uh, honey.. ya never heard of the Argon / Krypton, I guess?? Even this - really - isn't as much a 'whitelight' laser as an Ar/Kr, since even this 'comp' shows 3 sources, being 'optically combined' to come out the - EXTRAcavity - aperture as "white", whereas in an Ar/Kr, all those lines are produced in the same beam-path, INTRAcavity.. So, an Ar/Kr is even 'more a WL' than this..

    ..Still, we can take to the point that these will likely be easier to hang from yer ceiling as a 'lightbulb'... than an Ar/Kr...

    .02
    j
    ....and armed only with his trusty 21 Zorgawatt KTiOPO4...

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    I agree that this is a nice experiment, but it's primarily a technology demo rather than a significant development. The laser pumping makes sense as the band gap for the various colors will be different and the electrical drive will have to be isolated to prevent conduction from routing through the lowest potential pathway.

    A more appropriate example of a white light laser would be the recent development of supercontinum sources. Ultrafast lasers in the femtosecond and picosecond range fired into a non-linear fiber has been demonstrated to produce several octaves of intense light. You can buy these.

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    Considering in the existing chip, the lasing regions are side by side, so for the photos no dichros were used, just a collimating lens after a collection fiber..


    They get their 7 colors by modulating the 355 nm pump beams to three different doping regions in the chip.. The pics are beautiful, and it looks like the linearity graph is decent.

    The research paper itself mentions other previous white light systems in its reference, so the marketing people added the embellishment of "first".



    Still, its a nice, early generation, one of the first, monolithic RGB. I'm sure the work to develop the crystal growth techniques was not easy.



    Steve
    Last edited by mixedgas; 07-31-2015 at 07:37.
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    They also make no mention of the efficiency, they were pumping with a few uJ and measuring the output energy in 'ccd counts' which is usually on the order of picojoules for a decent CCD...

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    This is just progress... How big were our laser before? They're starting small now and grow from there... It's still very interesting.

    Fred.

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