Message ID: 6
Entry time: Wed Mar 17 19:51:42 2021
In reply to: 4
Reply to this: 7

Author:

Paco

Type:

General

Category:

Design specs

Subject:

Silicon TM dichroic coatings for phase I

Update on ETM

New optima are being found using the same basic code with some modifications, which I summarize below;

Updated wavelengths to be 2128.2 nm and 1418.8 nm (PSL and AUX resp.)

The thickness sensitivity cost "sensL" previously defined only for 2128 nm, is now incorporating AUX (1418 nm) in quadrature; so sensL = sqrt(sens(2128) ** 2 + sens(1418)**2)

There is now a "starfish" plot displaying the optimized vector cost. Basically, the scores are computed as the inverse of the weighted final scalar costs, meaning the better stats reach farther out in the chart. One of these scalar costs does not actually belong to the optimization (stdevL) and is just a coarse measure of the variance of the thicknesses in the stack relative to the average thickness.

Included a third wavelength as transOPLV (for the OPLEV laser) which tries to get R ~ 99 % at 632 nm

Imagine,... a third wavelength! Now the plots for the transmissivity curves go way into the visible region. Just for fun, I'm also showing the value at 1550 nm in case anyone's interested in that.

Adapted the MCMC modules (doMC, and cornerPlot) to check the covariance between the transmissivities at 2128 and 1418 for a given design.

Reintroduced significant weights for TO noise and Brownian noise cost functions (from 1e-11 to 1e-1) because it apparently forces solutions with lower thickness variance over the stack (not definitive, need to sample more)

Still working to translate all these changes to ITM, but here are samples for some optimum.

Attachment 1 shows the spectral reflectivity/transmissivity curves with a bunch of labels and the transparent inset showing the starfish plot. Kind of crazy still.

Attachment 2 shows the stack. Surprisingly not as crazy (or maybe I have internalized the old "crazy" as "normal")

Attachment 3 shows a very simple corner plot illustrating the covariance between the two main wavelengths transmissions.