Figure 5
From: Holographic planar lightwave circuit for on-chip spectroscopy
Optical responses of a 926 channel spectrometer. (a) Optical top-view photo of a chip illuminated at the input by a HeNe laser with an emission peak at 632.8 nm and a 10 pm FWHM bandwidth, TE polarization. The visible light rays coming out of the input edge (stray light) are due to a non-ideal matching between the modal size of the macroscopic optical fiber and the microscopic RWG. (b) Profile of the normalized light intensity at the spectrometer output; on the top, output light detected by photodetectors from the chip edge. (c) Response of the device to six different wavelengths and their relative correspondence to different channel numbers. (d) Linearity of the dispersion curve of the two-hologram spectrometer. The shape of the dispersion curve can by customized be design to assume any profile. FWHM, full-width at half-maximum; RWG, ridge waveguide; TE, transverse electric.
