If we assume kinetic energy of a proton is equal to the energy of a photon, the ratio of de Broglie wavelength of the proton to the photon is proportional to:

Let K.E. of proton = E
λp = h/√(2mE) (de Broglie wavelength of proton)
λphoton = hc/E (de Broglie wavelength of photon)
λp/λphoton = [h/√(2mE)] / [hc/E] = E¹/²/c√(2m)
Since c and m are constants, λp/λphoton ∝ E¹/²
Therefore, the ratio of de Broglie wavelength of proton to photon is proportional to E¹/².