on chip spectrometer?...

[whit3rd]

On Tuesday, October 25, 2022 at 8:52:40 AM UTC-7, John Larkin wrote:

On Tue, 25 Oct 2022 16:03:40 +0100, piglet <erichp...@hotmail.com
wrote:

Regular silicon detectors cover 900-300nm (or thereabouts) at low cost
so I wonder if a non-linear crystal can be switched in ahead of the
grating to double or triple 1600nm into the Si-detectable range. JL
wants to verify single bright monochromatic sources so losses needn\'t be
a worry?

A typical source is a connectorized fiber-coupled laser of a couple of
milliwatts. Multiplication usually requires very high powers.

The longest wavelength lasers that we now use are 1550, and we have
corresponding photodiodes. The shortest are 800, ditto.

A wavelength splitter and three photodiodes would at least identify
the band of a laser: 1500ish, 1300ish, and 850ish.

If there\'s enough energy to unbalance a thermistor bridge, a single detector
would handle the whole range. Just put one thermistor in shade, and expose
the other to the \'beam\'. That does require a mirror for beam forming from a
small-spot source, but no wavelengths omitted if you spend the money for a reflective
grating do do the wavelength selection. The replica gratings, at $1 each, don\'t
come with a lot of detailed specs for 1500 nm.

You\'d not want the operator to breathe on the detector, of course.

 

[Phil Hobbs]

piglet wrote:

On 23/10/2022 16:15, John Larkin wrote:
On Sun, 23 Oct 2022 14:27:56 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 23/10/2022 09:38, Jan Panteltje wrote:
On a sunny day (Sun, 23 Oct 2022 09:13:53 +0100) it happened Martin
Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tj2t42$1jlg$1@gioia.aioe.org>:

On 23/10/2022 06:39, Jan Panteltje wrote:
on chip spectrometer?
    https://www.sciencedaily.com/releases/2022/10/221020140615.htm

Possibly. I\'d like to see a bit more of the specifications and light
intensity it requires before I take that press release at face value.

There is a bit more here but the main article is behind a paywall

https://www.science.org/doi/10.1126/science.add8544

I see.
Well, CCD sensor with prism in front of it should work too?

The best super high resolution systems use an echelle method modest
dispersion prism one way and a very high dispersion grating at almost 90
degrees to it so as to map a linear spectrum onto a 2D rectangular CCD.

https://solarsystem.nasa.gov/resources/390/the-solar-spectrum/

That example was actually observed with a Fourier transform method and
then displayed in the fashion of a traditional echelle spectrum. It is a
very impressive piece of kit even it it only works on bright stars:

https://www.jstor.org/stable/26660057#metadata_info_tab_contents

This is a real physical highres echelle spectroscope

https://www.shelyak.com/le-woppshel-un-spectro-echelle-a-grande-resolution/?lang=en


They are seriously nice pieces of kit. PE did an atomic
absorption/emission spectroscope using a similar configuration and early
CCDs back in the 1990\'s. Must have been ~95 because I saw it in Japan at
one of the big analytical trade fairs where we were also exhibiting.

The spectrometer business seems to be a race for resolution in narrow
bands. There\'s no wide-range low-resolution stuff that we can find.

Something like a grating and a bunch of detectors could work. It would
have a lot of wavelength overlap confusion which could be mostly
computed out.


Regular silicon detectors cover 900-300nm (or thereabouts) at low cost
so I wonder if a non-linear crystal can be switched in ahead of the
grating to double or triple 1600nm into the Si-detectable range. JL
wants to verify single bright monochromatic sources so losses needn\'t be
a worry?

piglet

Even if they were 400 dB?

Seriously, optical materials are so linear that you really have to stand
on one leg to get any SH signal to speak of.

If you have a gigawatt of peak power, you can do a lot of things, e.g.
use topical disinfectant for SHG. Nitrofurazone (5-nitro 2-furaldehyde
semicarbazone, Aldrich Catalog #73340) does a good job of making a
little bit of visible from a whole lot of IR.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[piglet]

On 25/10/2022 23:06, Phil Hobbs wrote:

piglet wrote:
On 23/10/2022 16:15, John Larkin wrote:
On Sun, 23 Oct 2022 14:27:56 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 23/10/2022 09:38, Jan Panteltje wrote:
On a sunny day (Sun, 23 Oct 2022 09:13:53 +0100) it happened Martin
Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tj2t42$1jlg$1@gioia.aioe.org>:

On 23/10/2022 06:39, Jan Panteltje wrote:
on chip spectrometer?
    https://www.sciencedaily.com/releases/2022/10/221020140615.htm

Possibly. I\'d like to see a bit more of the specifications and light
intensity it requires before I take that press release at face value.

There is a bit more here but the main article is behind a paywall

https://www.science.org/doi/10.1126/science.add8544

I see.
Well, CCD sensor with prism in front of it should work too?

The best super high resolution systems use an echelle method modest
dispersion prism one way and a very high dispersion grating at
almost 90
degrees to it so as to map a linear spectrum onto a 2D rectangular CCD.

https://solarsystem.nasa.gov/resources/390/the-solar-spectrum/

That example was actually observed with a Fourier transform method and
then displayed in the fashion of a traditional echelle spectrum. It
is a
very impressive piece of kit even it it only works on bright stars:

https://www.jstor.org/stable/26660057#metadata_info_tab_contents

This is a real physical highres echelle spectroscope

https://www.shelyak.com/le-woppshel-un-spectro-echelle-a-grande-resolution/?lang=en

They are seriously nice pieces of kit. PE did an atomic
absorption/emission spectroscope using a similar configuration and
early
CCDs back in the 1990\'s. Must have been ~95 because I saw it in
Japan at
one of the big analytical trade fairs where we were also exhibiting.

The spectrometer business seems to be a race for resolution in narrow
bands. There\'s no wide-range low-resolution stuff that we can find.

Something like a grating and a bunch of detectors could work. It would
have a lot of wavelength overlap confusion which could be mostly
computed out.


Regular silicon detectors cover 900-300nm (or thereabouts) at low cost
so I wonder if a non-linear crystal can be switched in ahead of the
grating to double or triple 1600nm into the Si-detectable range. JL
wants to verify single bright monochromatic sources so losses needn\'t
be a worry?

piglet

Even if they were 400 dB?

Seriously, optical materials are so linear that you really have to stand
on one leg to get any SH signal to speak of.

If you have a gigawatt of peak power, you can do a lot of things, e.g.
use topical disinfectant for SHG. Nitrofurazone (5-nitro 2-furaldehyde
semicarbazone, Aldrich Catalog #73340) does a good job of making a
little bit of visible from a whole lot of IR.

Cheers

Phil Hobbs

I bow to your superior knowledge, my only experience was years ago my
kids had a tiny green laser pointer that ran off some button cells - the
green was doubled IR. The DC input power cannot possibly have been more
than 100-200 milliwatts. Whole thing was incredibly cheap and tiny.

piglet

 

[Lasse Langwadt Christensen]

onsdag den 26. oktober 2022 kl. 13.45.34 UTC+2 skrev erichp...@hotmail.com:

On 25/10/2022 23:06, Phil Hobbs wrote:
piglet wrote:
On 23/10/2022 16:15, John Larkin wrote:
On Sun, 23 Oct 2022 14:27:56 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 23/10/2022 09:38, Jan Panteltje wrote:
On a sunny day (Sun, 23 Oct 2022 09:13:53 +0100) it happened Martin
Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tj2t42$1jlg$1...@gioia.aioe.org>:

On 23/10/2022 06:39, Jan Panteltje wrote:
on chip spectrometer?
https://www.sciencedaily.com/releases/2022/10/221020140615.htm

Possibly. I\'d like to see a bit more of the specifications and light
intensity it requires before I take that press release at face value.

There is a bit more here but the main article is behind a paywall

https://www.science.org/doi/10.1126/science.add8544

I see.
Well, CCD sensor with prism in front of it should work too?

The best super high resolution systems use an echelle method modest
dispersion prism one way and a very high dispersion grating at
almost 90
degrees to it so as to map a linear spectrum onto a 2D rectangular CCD.

https://solarsystem.nasa.gov/resources/390/the-solar-spectrum/

That example was actually observed with a Fourier transform method and
then displayed in the fashion of a traditional echelle spectrum. It
is a
very impressive piece of kit even it it only works on bright stars:

https://www.jstor.org/stable/26660057#metadata_info_tab_contents

This is a real physical highres echelle spectroscope

https://www.shelyak.com/le-woppshel-un-spectro-echelle-a-grande-resolution/?lang=en

They are seriously nice pieces of kit. PE did an atomic
absorption/emission spectroscope using a similar configuration and
early
CCDs back in the 1990\'s. Must have been ~95 because I saw it in
Japan at
one of the big analytical trade fairs where we were also exhibiting.

The spectrometer business seems to be a race for resolution in narrow
bands. There\'s no wide-range low-resolution stuff that we can find.

Something like a grating and a bunch of detectors could work. It would
have a lot of wavelength overlap confusion which could be mostly
computed out.


Regular silicon detectors cover 900-300nm (or thereabouts) at low cost
so I wonder if a non-linear crystal can be switched in ahead of the
grating to double or triple 1600nm into the Si-detectable range. JL
wants to verify single bright monochromatic sources so losses needn\'t
be a worry?

piglet

Even if they were 400 dB?

Seriously, optical materials are so linear that you really have to stand
on one leg to get any SH signal to speak of.

If you have a gigawatt of peak power, you can do a lot of things, e.g.
use topical disinfectant for SHG. Nitrofurazone (5-nitro 2-furaldehyde
semicarbazone, Aldrich Catalog #73340) does a good job of making a
little bit of visible from a whole lot of IR.

Cheers

Phil Hobbs


I bow to your superior knowledge, my only experience was years ago my
kids had a tiny green laser pointer that ran off some button cells - the
green was doubled IR. The DC input power cannot possibly have been more
than 100-200 milliwatts. Whole thing was incredibly cheap and tiny.

maximum for a legal laser pointer is 5mW

 

[piglet]

On 26/10/2022 13:19, Lasse Langwadt Christensen wrote:

onsdag den 26. oktober 2022 kl. 13.45.34 UTC+2 skrev erichp...@hotmail.com:
On 25/10/2022 23:06, Phil Hobbs wrote:
piglet wrote:
On 23/10/2022 16:15, John Larkin wrote:
On Sun, 23 Oct 2022 14:27:56 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 23/10/2022 09:38, Jan Panteltje wrote:
On a sunny day (Sun, 23 Oct 2022 09:13:53 +0100) it happened Martin
Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tj2t42$1jlg$1...@gioia.aioe.org>:

On 23/10/2022 06:39, Jan Panteltje wrote:
on chip spectrometer?
https://www.sciencedaily.com/releases/2022/10/221020140615.htm

Possibly. I\'d like to see a bit more of the specifications and light
intensity it requires before I take that press release at face value.

There is a bit more here but the main article is behind a paywall

https://www.science.org/doi/10.1126/science.add8544

I see.
Well, CCD sensor with prism in front of it should work too?

The best super high resolution systems use an echelle method modest
dispersion prism one way and a very high dispersion grating at
almost 90
degrees to it so as to map a linear spectrum onto a 2D rectangular CCD.

https://solarsystem.nasa.gov/resources/390/the-solar-spectrum/

That example was actually observed with a Fourier transform method and
then displayed in the fashion of a traditional echelle spectrum. It
is a
very impressive piece of kit even it it only works on bright stars:

https://www.jstor.org/stable/26660057#metadata_info_tab_contents

This is a real physical highres echelle spectroscope

https://www.shelyak.com/le-woppshel-un-spectro-echelle-a-grande-resolution/?lang=en

They are seriously nice pieces of kit. PE did an atomic
absorption/emission spectroscope using a similar configuration and
early
CCDs back in the 1990\'s. Must have been ~95 because I saw it in
Japan at
one of the big analytical trade fairs where we were also exhibiting.

The spectrometer business seems to be a race for resolution in narrow
bands. There\'s no wide-range low-resolution stuff that we can find.

Something like a grating and a bunch of detectors could work. It would
have a lot of wavelength overlap confusion which could be mostly
computed out.


Regular silicon detectors cover 900-300nm (or thereabouts) at low cost
so I wonder if a non-linear crystal can be switched in ahead of the
grating to double or triple 1600nm into the Si-detectable range. JL
wants to verify single bright monochromatic sources so losses needn\'t
be a worry?

piglet

Even if they were 400 dB?

Seriously, optical materials are so linear that you really have to stand
on one leg to get any SH signal to speak of.

If you have a gigawatt of peak power, you can do a lot of things, e.g.
use topical disinfectant for SHG. Nitrofurazone (5-nitro 2-furaldehyde
semicarbazone, Aldrich Catalog #73340) does a good job of making a
little bit of visible from a whole lot of IR.

Cheers

Phil Hobbs


I bow to your superior knowledge, my only experience was years ago my
kids had a tiny green laser pointer that ran off some button cells - the
green was doubled IR. The DC input power cannot possibly have been more
than 100-200 milliwatts. Whole thing was incredibly cheap and tiny.

maximum for a legal laser pointer is 5mW

Exactly! But PH was saying doubling required huge power, I doubt the
kids toy lipstick sized pointer optical output was even a milli-watt but
it showed optical doubling happens at sub-watt levels?

piglet

 

[Lasse Langwadt Christensen]

onsdag den 26. oktober 2022 kl. 17.15.35 UTC+2 skrev erichp...@hotmail.com:

On 26/10/2022 13:19, Lasse Langwadt Christensen wrote:
onsdag den 26. oktober 2022 kl. 13.45.34 UTC+2 skrev erichp...@hotmail.com:
On 25/10/2022 23:06, Phil Hobbs wrote:
piglet wrote:
On 23/10/2022 16:15, John Larkin wrote:
On Sun, 23 Oct 2022 14:27:56 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 23/10/2022 09:38, Jan Panteltje wrote:
On a sunny day (Sun, 23 Oct 2022 09:13:53 +0100) it happened Martin
Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tj2t42$1jlg$1...@gioia.aioe.org>:

On 23/10/2022 06:39, Jan Panteltje wrote:
on chip spectrometer?
https://www.sciencedaily.com/releases/2022/10/221020140615.htm

Possibly. I\'d like to see a bit more of the specifications and light
intensity it requires before I take that press release at face value.

There is a bit more here but the main article is behind a paywall

https://www.science.org/doi/10.1126/science.add8544

I see.
Well, CCD sensor with prism in front of it should work too?

The best super high resolution systems use an echelle method modest
dispersion prism one way and a very high dispersion grating at
almost 90
degrees to it so as to map a linear spectrum onto a 2D rectangular CCD.

https://solarsystem.nasa.gov/resources/390/the-solar-spectrum/

That example was actually observed with a Fourier transform method and
then displayed in the fashion of a traditional echelle spectrum. It
is a
very impressive piece of kit even it it only works on bright stars:

https://www.jstor.org/stable/26660057#metadata_info_tab_contents

This is a real physical highres echelle spectroscope

https://www.shelyak.com/le-woppshel-un-spectro-echelle-a-grande-resolution/?lang=en

They are seriously nice pieces of kit. PE did an atomic
absorption/emission spectroscope using a similar configuration and
early
CCDs back in the 1990\'s. Must have been ~95 because I saw it in
Japan at
one of the big analytical trade fairs where we were also exhibiting.

The spectrometer business seems to be a race for resolution in narrow
bands. There\'s no wide-range low-resolution stuff that we can find.

Something like a grating and a bunch of detectors could work. It would
have a lot of wavelength overlap confusion which could be mostly
computed out.


Regular silicon detectors cover 900-300nm (or thereabouts) at low cost
so I wonder if a non-linear crystal can be switched in ahead of the
grating to double or triple 1600nm into the Si-detectable range. JL
wants to verify single bright monochromatic sources so losses needn\'t
be a worry?

piglet

Even if they were 400 dB?

Seriously, optical materials are so linear that you really have to stand
on one leg to get any SH signal to speak of.

If you have a gigawatt of peak power, you can do a lot of things, e.g.
use topical disinfectant for SHG. Nitrofurazone (5-nitro 2-furaldehyde
semicarbazone, Aldrich Catalog #73340) does a good job of making a
little bit of visible from a whole lot of IR.

Cheers

Phil Hobbs


I bow to your superior knowledge, my only experience was years ago my
kids had a tiny green laser pointer that ran off some button cells - the
green was doubled IR. The DC input power cannot possibly have been more
than 100-200 milliwatts. Whole thing was incredibly cheap and tiny.

maximum for a legal laser pointer is 5mW

Exactly! But PH was saying doubling required huge power, I doubt the
kids toy lipstick sized pointer optical output was even a milli-watt but
it showed optical doubling happens at sub-watt levels?

doesn\'t take much to make it not work, https://youtu.be/9tOcUyakk0Q

 

[Jan Panteltje]

On a sunny day (Wed, 26 Oct 2022 16:15:28 +0100) it happened piglet
<erichpwagner@hotmail.com> wrote in <tjbiug$2g6r6$1@dont-email.me>:

Exactly! But PH was saying doubling required huge power, I doubt the
kids toy lipstick sized pointer optical output was even a milli-watt but
it showed optical doubling happens at sub-watt levels?

piglet

Most of your questions are answered here:
https://www.rp-photonics.com/frequency_doubling.html#:~:text=Frequency%20doubling%20is%20a%20frequently,usually%20based%20on%20this%20approach.

https://www.quora.com/Semiconductors-How-does-a-frequency-doubler-work-in-a-green-laser-pointer

OTOH there are now green laser diodes (not doubling).
I have an iconnect picop laser projector,
it is said it uses a true red, green and blue laser (green not doubling)

Nice thing to play with.
https://www.sapiensbryan.com/review-i-connect-view-x-laser-pico-projector-ipod-iphone-ipad-compatible/
that was already 10 years or longer ago, I did read it uses a true green laser (else scan artifacts I\'d think)
Its all low power.

You cn test if your green laser is doubling (and uses high energy pulses) by swinging it
against some wall and see it it produces a line of dots (swicthing frequency)
But if it is younger than 10 years maybe it is just a green laser diode?

https://arstechnica.com/gadgets/2009/07/green-diode-lasers-a-big-breakthrough-for-laser-display-tech/

 

[Phil Hobbs]

piglet wrote:

On 25/10/2022 23:06, Phil Hobbs wrote:
piglet wrote:
On 23/10/2022 16:15, John Larkin wrote:
On Sun, 23 Oct 2022 14:27:56 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 23/10/2022 09:38, Jan Panteltje wrote:
On a sunny day (Sun, 23 Oct 2022 09:13:53 +0100) it happened
Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote in <tj2t42$1jlg$1@gioia.aioe.org>:

On 23/10/2022 06:39, Jan Panteltje wrote:
on chip spectrometer?
    https://www.sciencedaily.com/releases/2022/10/221020140615.htm

Possibly. I\'d like to see a bit more of the specifications and light
intensity it requires before I take that press release at face
value.

There is a bit more here but the main article is behind a paywall

https://www.science.org/doi/10.1126/science.add8544

I see.
Well, CCD sensor with prism in front of it should work too?

The best super high resolution systems use an echelle method modest
dispersion prism one way and a very high dispersion grating at
almost 90
degrees to it so as to map a linear spectrum onto a 2D rectangular
CCD.

https://solarsystem.nasa.gov/resources/390/the-solar-spectrum/

That example was actually observed with a Fourier transform method and
then displayed in the fashion of a traditional echelle spectrum. It
is a
very impressive piece of kit even it it only works on bright stars:

https://www.jstor.org/stable/26660057#metadata_info_tab_contents

This is a real physical highres echelle spectroscope

https://www.shelyak.com/le-woppshel-un-spectro-echelle-a-grande-resolution/?lang=en


They are seriously nice pieces of kit. PE did an atomic
absorption/emission spectroscope using a similar configuration and
early
CCDs back in the 1990\'s. Must have been ~95 because I saw it in
Japan at
one of the big analytical trade fairs where we were also exhibiting.

The spectrometer business seems to be a race for resolution in narrow
bands. There\'s no wide-range low-resolution stuff that we can find.

Something like a grating and a bunch of detectors could work. It would
have a lot of wavelength overlap confusion which could be mostly
computed out.


Regular silicon detectors cover 900-300nm (or thereabouts) at low
cost so I wonder if a non-linear crystal can be switched in ahead of
the grating to double or triple 1600nm into the Si-detectable range.
JL wants to verify single bright monochromatic sources so losses
needn\'t be a worry?

piglet

Even if they were 400 dB?

Seriously, optical materials are so linear that you really have to
stand on one leg to get any SH signal to speak of.

If you have a gigawatt of peak power, you can do a lot of things, e.g.
use topical disinfectant for SHG. Nitrofurazone (5-nitro 2-furaldehyde
semicarbazone, Aldrich Catalog #73340) does a good job of making a
little bit of visible from a whole lot of IR.

Cheers

Phil Hobbs



I bow to your superior knowledge, my only experience was years ago my
kids had a tiny green laser pointer that ran off some button cells - the
green was doubled IR. The DC input power cannot possibly have been more
than 100-200 milliwatts. Whole thing was incredibly cheap and tiny.

piglet

Yes, you can do that at surprisingly low power, but it takes focusing
the beam down in just the right material, cut with the crystal axes just
so.

The issues are:
(1) the size of the elements in the nonlinear susceptibility tensor
chi\'\' (normally very small except in special materials), and
(b) getting the nonlinear electric polarization (*) to phase-match with
a propagating wave at the second harmonic, which it normally doesn\'t.

A good material has large coefficients of chi-double-prime, which helps
with the first, and enough birefringence, which makes the second possible.

The reason phase matching matters is that the growth of the
second-harmonic wave is a coupled-modes problem--the fundamental beam
causes a component of polarization at the second harmonic, and the SH
beam grows from that, just like a microwave directional coupler.

The k vector of the SH _polarization_ is obviously exactly twice that of
the fundamental beam, whereas the SH _beam\'s_ k vector is defined by the
frequency and refractive index. (Normally the refractive index increases
considerably towards short wavelengths, so this does not happen by
accident.)

Cheers

Phil Hobbs

(*) This is dielectric polarization, the material response to the
applied field, not polarization as in linear or circular or elliptical
polarization of a propagating wave.

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com