Hi. Reading this survey may give your some idea:

https://scholar.harvard.edu/files/yetisen/files/photonic_crystal_fiber_based_plasmonic_sensors.pdf

Often, the target analyte defines the choice of the metals for PFC sensing. It is right that gold renders good performance, however, copper and silver also possess some unique features. For instance, through adoption of silver, one can attain stability in response whereas gold yields better sensitivity. However, through adoption of suitable functionalities akin to the target, there is feasibility of enhancing the sensing yield of other metals as that of gold.

Rajib Biswas Seyed Hadi Badri A. K. Pathak

Thank you sir trying to work on your suggestions

Hi. It's depend of the working wavelength. The best plasmonic effect with the lower losses is obtain when the real part of permittivity of the metal tend to 0 and the imaginary part is high as possible. To select the best metal for your application, data library like refractiveindex.info on the web site can be help you.

Regards,

Regis Orobtchouk

Regis Orobtchouk thank you sir