A typical use of linear or two dimensional spectrometers is to expose the detector area, and then shift the photo-electric charges out of the device in a serial fashion. If the illuminating signal is spatially narrow relative to the size of the array, this will drive down the percent of the detector that is utilized, as only a relatively small number of pixels are used to detect the beam. The present invention proposes a method which capitalizes on this spatial under-utilization, and alters the clocking scheme to maximize the read-out speed of the pixels containing signal information. This type of clocking scheme raises the optical power saturation level of the spectrometer. Such an improvement in optical power handling is beneficial for spectrometer based detection of resonant waveguide grating biochemical binding, since in such systems the performance is frequently limited by spectrometer saturation.