CUPID (CUORE Upgrade with Particle IDentification) will be a tonne-scale bolometric experiment searching for the neutrinoless double beta decay. CUPID aims to improve CUORE sensitivity to this nuclear transition by isotope enrichment and substantial background reduction. The CUORE limiting background is due to degraded-energy α \alpha particles emitted at surfaces close to the detector, that a pure calorimetric measurement - like the one performed by CUORE - is not able to tag. We will present the potential of using the feeble light emitted by TeO2 _2 crystals, used by the CUORE experiment to study the promising isotope 130 ^{130} Te, to separate the α particles from the signals. In particular we will show the results obtained by a bolometric light detector assisted by the Neganov-Luke effect, which amplifies the weak light signals thanks to an electric field.This device, coupled to a CUORE-size crystal, was able to reject 99.9% of α \alpha 's with an acceptance of 96.3% of β \beta events.