Nature Photonics 1, 180–185 (2007)

In the above article, the authors wish to correct the sentence on page 182, column 1, line 6 that begins “The volume conductivity...”, so that it reads:

The current flow through a 12-μm-thick sol–gel cladding layer was measured against temperature and rendered as an Arrhenius plot (see our other work, ref. 4), giving 1.0 μA for applied voltages of 400 V and 600 V and a poling temperature of 135 °C. This indicated that the conductivity of the sol–gel was significantly larger than the EO polymer, when a poling field of 50–95 V μm−1 was applied to a single EO polymer film at the poling temperature.