Dammit!

Light and its behaviour and properties
Din
Posts: 402
Joined: Thu Mar 12, 2015 4:47 pm

Dammit!

Post by Din »

Dammit! Thought of this about 10 years ago. Yes, I know the joke:
How many holographers does it take to change a light bulb? 10, one to change the bulb and 9 to say, "I thought of that 10 years ago!"

About 1987, Tomasz Jannsen (owner POC) and I were talking about using the WKB approximation to model volume holograms, since I believed Kogelnik wasn't designed for the new photopolymers coming out then. Anyway, some 25 years later, ~2012, I was working on holographic diffractive waveguides for the research division of a hi-tech company that shall remain nameless; the method by which some VR/AR/MR goggles, which seemed to be an up-and-coming technology in 2012, work by diffractive waveguides. One of the problems was not being able to quantify and characterise these waveguides in photopolymers. Recalling that long-ago discussion on WKB methods with Tomasz, I wondered if it was possible to use digital holography along with a WKB approximation. Not having the tools for digital holography, I sketched out some notes and let the whole idea go. Now, here it is in JOSA B - Optical Physics!
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lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Dammit!

Post by lobaz »

I guess most researchers are on the same boat :)
Anyway, after reading the article, do you think that WKB approximation is a useful tool here? Not every published method is useful in the end...
Din
Posts: 402
Joined: Thu Mar 12, 2015 4:47 pm

Re: Dammit!

Post by Din »

lobaz wrote: Sun Jun 20, 2021 12:51 pm I guess most researchers are on the same boat :)
They're trying to characterise the refractive index profile (RIP) of the new waveguides made from polymers, which have a kind of RIP not seen before (below).

As you can see, the RIP is rapidly changing near the origin, and then varies slowly away from the origin. Such problems are ideal for applying the WKB approximation. They're splitting the profile into sections and analysing each section using a series approximation.

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Din
Posts: 402
Joined: Thu Mar 12, 2015 4:47 pm

Re: Dammit!

Post by Din »

The actual profile didn't show up (despite it showing up on the preview!). here it is:
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Din
Posts: 402
Joined: Thu Mar 12, 2015 4:47 pm

Re: Dammit!

Post by Din »

Having got the profile, they then solve Maxwell inserting the appropriate RIP, and then getting the transmission modes in the waveguide. You can see the modes below. The experimental setup uses a Mach Zender with the sample waveguide placed in one arm.
The attachment profile 3.jpg is no longer available
The attachment profile 3.jpg is no longer available
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Din
Posts: 402
Joined: Thu Mar 12, 2015 4:47 pm

Re: Dammit!

Post by Din »

The experimental setup did not show up 9again, the preview showed it!
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Din
Posts: 402
Joined: Thu Mar 12, 2015 4:47 pm

Re: Dammit!

Post by Din »

lobaz wrote: Sun Jun 20, 2021 12:51 pm I guess most researchers are on the same boat :)
Yep! :D
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