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

Dana Whitlow k8yumdoober at gmail.com
Mon Jun 11 07:29:58 EDT 2018


I should have written more clearly- the adhesive in question was *not* in
the optical path.

As is usual, variations are possible, one supposedly being that the crystal
that lases
at 1064 nm is also doped with something to make it nonlinear (so I've
read).  I kind of
have my doubts over this, however it seems like asking too much of a single
substance to do "double" duty without some unwanted compromises.

Dana


On Mon, Jun 11, 2018 at 6:06 AM, Bruce Griffiths <bruce.griffiths at xtra.co.nz
> wrote:

> 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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