Abstract
An improved compact 1x2 digital optical switch (DOS) in InGaAsP/InP is studied, and the experimental results are compared to numerical modeling. We present measurements of Mach-Zehnder and DOS devices fabricated with InGaAsP cores having bandgap energies corresponding to wavelengths of 1.2 um, 1.3 um, and 1.4 um. The results are compared with modeling evaluation of refractive index change versus carrier concentration in the different InGaAsP alloys. The effects of modifications in the wafer layer structure are presented as well. Switching current is significantly reduced from greater than 100 mA to about 20 mA, resulting in significant power savings, and in addition eliminating thermal overshoot in the switched optical pulse. The DOS has a measured switching contrast ratio of better than 12 dB with a switching rise time of less than 10 nsec.