[time-nuts] where can I purchase 794.7 nm VCSEL for building CPT rubidium clock?

[Bruce Griffiths]

The better ones use optically contacted crystals to avoid browning of the adhesive due to the high power densities of the 1064nm laser required for efficient frequency doubling.

Brue
> On 11 June 2018 at 22:52 Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> 
> Mark's description about how (most) green laser pointers work The better is a bit in
> error, and is perhaps
> over-simplified- the reality is actually more fascinating yet:
> 
> First a diode laser operating at around 808 or 809 nm is used to optically
> pump a solid
> state laser which generates light at 1064 nm.  This light is then frequency
> doubled with an
> intra-cavity nonlinear element to produce the final  output at 532 nm.
>  For all this to work
> the optical elements must be critically aligned, and to me the most amazing
> thing about
> the low selling price is how this alignment is effected so cheaply.  One of
> these units I've
> opened up has the doubler crystal held down by a lump of cement on one
> side- it looks
> for all the world like it must have pushed into alignment and "held" there
> while the cement
> was cured.  Green pointers made in this way are characterized by quite good
> beam quality
> and very little wavelength spread from unit to unit. However, they are
> generally quite
> delicate and ruined by mechanical shock.
> 
> Although not commonly known, at least one outfit (Z-Bolt) is now selling
> "direct diode"
> green pointers, where there is just one laser which emits directly in the
> green, at around
> 515-530 nm.   These are much more robust, operate well over a wider
> temperature range,
> but have the usual poor beam quality (non-circular beam with some residual
> astigmatism)
> characteristic of diode lasers made with simple collimating optics.  And,
> the output
> wavelength spread from unit to unit is quite large.
> 
> Dana
> 
> 
> On Mon, Jun 11, 2018 at 2:43 AM, Mark Sims <holrum at hotmail.com> wrote:
> 
> > Well, no.  Green laser pointers convert a rather high power 800 nm laser
> > to 1600 nm in one crystal then divide it to 533 nm in another one.   The
> > physics and manufacturing of them is best described as black magic.  They
> > are cheap because China developed the process to grow the crystals in bulk
> > and crank out zillions of them for consumer products.
> >
> > I suspect that a 1600-ish nm to 800-ish nm converter is not a stock
> > consumer-quantity device and will cost a pretty penny or two... like a
> > red/IR laser diode can be had for 50 cents and a telecom VCSEL diode can be
> > $500.
> >
> > ------------------
> >
> > > It cannot be too much, given the fact that these are used in
> > green laser pointers.
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