(a)
(b)
Figure 4: Experimental setup for measuring optical spectrum. (a) Measurement of optical transmission spectrum coupling tunable TE laser into the waveguide grating and the measuring light transmitted through the waveguide with power meter. (b) Measurement of optical reflection spectrum by coupling amplified spontaneous emission into waveguide grating through the 2 × 2 coupler and detecting reflected light with optical spectrum analyzer (OSA).