A method for reducing polarization comprising: acquiring detection events with a radiation detector comprising a semiconductor plate, wherein the detector is configured to produce electrical signals in response to absorption of ionizing radiation in the semiconductor plate, wherein electrons and holes are generated responsive to absorption of the ionizing radiation, the holes including groups of holes having different effective masses for corresponding different valence energy bands, wherein the semiconductor plate comprises a first surface, a second surface, and sidewalls, the first surface opposed to the second surface and the sidewalls interposed between the first surface and the second surface, wherein a cathode electrode is disposed on the first surface and pixelated anode electrodes disposed on the second surface; and optically coupling infrared radiation into the semiconductor plate via the sidewalls; wherein the IR radiation has at least one wavelength selected from a spectral range including wavelengths to which the semiconductor plate is partially transparent and which are configured to excite at least some of the holes from a first group at a first valence energy band to a second group at a second valence energy band, wherein the holes of the second group have lower effective masses than corresponding holes of the first group; characterised in that: the IR radiation is optically coupled into a first portion of at least one of the sidewalls of the semiconductor plate of the radiation detector, and the IR radiation is not coupled into a second portion of the at least one of the sidewalls; wherein the first portion of the at least one of the sidewalls corresponds to a non-depleted region and wherein the second portion of the at least one of the sidewalls corresponds to a depletion region. acquiring detection events with a radiation detector comprising a semiconductor plate, wherein the detector is configured to produce electrical signals in response to absorption of ionizing radiation in the semiconductor plate, wherein electrons and holes are generated responsive to absorption of the ionizing radiation, the holes including groups of holes having different effective masses for corresponding different valence energy bands, wherein the semiconductor plate comprises a first surface, a second surface, and sidewalls, the first surface opposed to the second surface and the sidewalls interposed between the first surface and the second surface, wherein a cathode electrode is disposed on the first surface and pixelated anode electrodes disposed on the second surface; and optically coupling infrared radiation into the semiconductor plate via the sidewalls; wherein the IR radiation has at least one wavelength selected from a spectral range including wavelengths to which the semiconductor plate is partially transparent and which are configured to excite at least some of the holes from a first group at a first valence energy band to a second group at a second valence energy band, wherein the holes of the second group have lower effective masses than corresponding holes of the first group; characterised in that: the IR radiation is optically coupled into a first portion of at least one of the sidewalls of the semiconductor plate of the radiation detector, and the IR radiation is not coupled into a second portion of the at least one of the sidewalls; wherein the first portion of the at least one of the sidewalls corresponds to a non-depleted region and wherein the second portion of the at least one of the sidewalls corresponds to a depletion region. the IR radiation is optically coupled into a first portion of at least one of the sidewalls of the semiconductor plate of the radiation detector, and the IR radiation is not coupled into a second portion of the at least one of the sidewalls; wherein the first portion of the at least one of the sidewalls corresponds to a non-depleted region and wherein the second portion of the at least one of the sidewalls corresponds to a depletion region.