Beam propagation in z direction

[davcm]

Hello,
As I am a newbie in this program, my question may be stupid or very easy to solve, so, firstly, I apologize myself if this is the case:
I am trying to simulate a photonic crystal using Optiwave. When I perform the tutorials, the final result is the expected one. But, when I try to do mine, I observe that, when I only put an Input field (Gaussian modulated CW; propagation direction +z), a wafer (4×4; material: air) and two observation points (reflected and transmited), in the analyzer I can see that there is Electric field propagating along the Z axis. And I do not know why is this.

What am I doing wrong?

Thank you.

David.

[Damian Marek]

Hi davcm,

Can you please attach your project file? Also I am not exactly sure what the problem is. You placed a z direction plane wave and the electricl field is propagating along the z axis as I believe it should.

Regards,
Damian

[davcm]

Hello Damian,
I guess my explanations were not good enough: the simulation occurs in the free space. I am working with an Input field (Gaussian modulated CW; propagation direction +z; polarization linear Ey), a wafer (4×4; material: air (so, free space)) and two observation points (reflected and transmited). So, as it is free space, no Ez component should appear (only Ey, and Hx). But, when I visulize both observation points I get an electric field with Ex, Ey and Ez components. What it should not be because the propagation direction is perpendicular to the polarization one.

Thanks a lot!

PD: simulation is in 3D. I attach both files, the design and the analysis ones.

Attachments:

1. prueba.fdt

[Damian Marek]

The coupling of the Maxwell equations as well as the numerical approximation, reflections caused at boundaries result in a signal that is not entirely polarized. However, you will notice that the x and z components are much smaller in amplitude then the y component.

If you work out the maxwell equations you will notice the reliance of the Ex field on the derivative of the Ey and Ez field. Even if you assume the Ez field is zero, the slight change in Ey along z will induce an Ex component. The plane wave assumption does not completely work at this level and the polarization will not be completely linear.

Hope this clears things up!

[Damian Marek]

I actually just found a good paper that describes it with more math and with a better explanation that I could!

http://www.victoria.ac.nz/scps/about/staff/pdf/Polarization_of_tightly_focused_laser_beams.pdf

[davcm]

Sorry,
If I attach the analysis file, it takes me long time to send you the message so this is why I only atteched one in the previous message.

Regards,
David.

[davcm]

Ok! Thanks a lot for the explanation and for the biblography attached!

[surjit]

hello ,
i might be having a similar type of question and i have submitted my query in BPM section and its waiting moderation.
i am using a tapered fiber struture and i want to see the electric field propagation in z direction where the multimode interference pattern can be observe.But i am unable to obtain the electric field propagation ,Can anyone guide me into this?

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