# phase of circular polarization light

Hi.

I'm calculating the phase and conversion efficiency of circular polarization light in a metasurface structure.

Before designing my own structure, I'm trying to reproduce the reported results of "Broadband achromatic metalens in the midinfrared range".

I can get same result of the conversion efficiency as shown In Fig 2. However, the calculated phase value is quite different compared with the paper's result.

How can I calculate the phase delay of LCP or RCP induced by metasurfaces?

I attached my source code, FDTD file, and the paper.

Thanks

## Answers

15Hi @Myunghwan,

Thank you for posting your question. Unfortunately, Ansys employees are not allowed to download any files posted here. We can only provide some guidelines. Could you give some detail on how you performed the calculation? Feel free to post screen capture of the settings and script used for the calculation.

I noted here that you were interested in obtaining the S parameters of the meta surface for a circular polarization. I assume you are using the S parameters to get the phase information. Is this correct?

The issue you encountered might be due to problem in the S-parameter extraction setting. Please refer to Metamaterial S parameter extraction for more information about the methodology and limitation.

4Hi.

First, I tried to use the S parameter analysis function. However, it is difficult to modify the source code for applying with circular polarization source cases.

To calculate the phase delay induced by metasurface, I launched a RCL source, and then calculated the conversion efficiency and phase delay from monitored Ex and Ey.

The conversion efficiency is quite correct, but the phase delay is not correct.

I attached workspace and source code.

I would appreciate it if you could review it

Thanks

i = sqrt(-1) ;

# Get data from monitor

m = "Tm";

f=getdata(m,"f");

x = getdata(m,"x");

y = getdata(m,"y");

Ex = getdata(m,"Ex");

Ey = getdata(m,"Ey");

# phase calculation

E_r = (Ex - 1i*Ey)/sqrt(2);

E_l = (Ex + 1i*Ey)/sqrt(2);

# phase compensation

E_r = pinch(E_r(length(x)/2+0.5,length(y)/2+0.5,1,:)) * exp(-i*2*pi*f/c*1.45*2.5*10^-6) * exp(-i*2*pi*f/c*(3-0.6)*10^-6) ;

E_l= pinch(E_l(length(x)/2+0.5,length(y)/2+0.5,1,:)) * exp(-i*2*pi*f/c*1.45*2.5*10^-6) * exp(-i*2*pi*f/c*(3-0.6)*10^-6) ;

phase_L = angle(E_l) ;

phase_R = angle(E_r) ;