An apparatus for receiving optical signal, which comprises: an optical fibre, a portion of which is covered; at least one strip of nanomaterial encircling the uncovered portion of said fibre; and a photodetector coupled to one end of said fibre, for converting optical signal to electric signal; whereby during use, an optical signal of at least one wavelength is laterally excited onto said nanomaterial-encircled portion, such that said nanomaterial will scatter the signal into said fibre through which the scattered signal will be guided to said photodetector.