Learning Forum

[jannatul nayem]

What kind of source is used to design a spr biosensor in d shaped optical fiber

[Guilin Sun]

The source is the exitation source. Depending on the device condifguration, it can be mode source from the regular fiber, or D-shaped fiber, or that region that can create SPR.  Please find some reference papers and check what they use, and what is the dimension of the whole device. FDTD may not be very friendly if the dimension is in mm or longer, with cross section in hundreds of microns.

[jannatul nayem]

https://www.researchgate.net/publication/279215399_Graphene_Enhances_the_Sensitivity_of_Fiber-Optic_Surface_Plasmon_Resonance_Biosensor

in the paper sayes collimated source.i am not understanding where to put it..i have posted some pictures below.

I am very new to lumerical fdtd.please correct me if i am wrong.

 

 

 

[jannatul nayem]

in the paper sayes collimated source.i am not understanding where to put it..i have posted some pictures below.

I am very new to lumerical fdtd.please correct me if i am wrong.

[Guilin Sun]

 

Collimated source in lab usually means plane wave in FDTD. But for coupling, collimated source might not be efficient. Focused gaussian beam can be better. Please try. It is the excitation source that is required in FDTD.

If you are new, please visit some online videos:  https://optics.ansys.com/hc/en-us/sections/360007813194-FDTD100-List-of-videos

 

[jannatul nayem]

 

If i use plane wave how do i will know that SPR is happening and how i will incident the source as TM polarized?and does the structure look correct to you?

 

[Guilin Sun]

It can be very challenge if you use plane wave source. I do not know where is the location to generate the SPP. You can use mode source to find the SPP mode at the location you know, and check its characteristics.

usually, you can get some information through transmission, eg there is a wavelength that exhibits extraodinary behavior. eg, sharp transmission decline etc.

For non-periodic structure, plane wave will be truncated by PML and create diffraction. Might be better to use Gaussian source.

you will need try different settings and see if the desired phenomenon occurs.  You will need to have a better understanding of SPP mode. You can use mode expansion monitor to check how much the transmission is for this SPP mode. Please read SPP and mode expansion monitor online.

[jannatul nayem]

okay,thank you