How can create something similar to vegetation index in sentinel 1 by using VV and VH polaristions?

I have this imagery " Intensity_S1B_IW_SLC__1SDV_20171219T171554_ABAE_clip" so with “IW and SLC” modes . i tried calculating a ratio of VH/VV but it gave me a black image. How is it possible to detect vegetation and then create an index?

IW and SLC are not “modes”

IW is the acquisition mode - Interferometric Wide
SLC refers to the Level-1 data type - Single look complex

There are different ways to detect vegetation you could try using GRD data instead of SLC . Calibrate , reduce speckles and perform classification with both polarizations+ VH/VV

With SLC you could have additionally the coherence which could be the nice indicator of vegetated areas (usually low coherence)