Anisotropy of photocurrent for two-photon absorption photodetector made of hemispherical silicon with $(\overline{1}10)$ plane

We fabricated a hemispherical nearly-intrinsic Si-based photodetector with ( plane. The photocurrent generated from the detector under a continuous wave laser at the wavelength of 1.3 μm was observed. The photocurrent shows a quadratic dependence on the incident optical power. The dependence of the photocurrent on the azimuth of the incident optical field is consistent with the anisotropy of the two-photon absorption in Si crystals. The ratio of the two nonzero independent components of the third-order susceptibility of silicon is obtained to be 0.42 from the observed result of the anisotropy of the photocurrent.