MODELING THE OPTIMUM PERFORMANCE OF INGAAS/INP-BASED ASYMMETRIC FABRY-PEROT MODULATOR DEVICES

The performance of long-wavelength asymmetric Fabry-Perot modulator (AFPM) devices has been modelled to establish whether InGaAs/InP multiple quantum well (MQW) material can yield the high contrast (in-state:off-state) of 100:1 observed at shorter wavelengths using GaAs/AlGaAs. The absorption and electroabsorption spectra for MQWS with 70 AA barriers were predicted using photocurrent data from single 45, 78 or 110 AA InGaAs wells. Using these spectra the thickness of intrinsic MQW material required to obtain the necessary absorbance changes was calculated. The widest wells lead to the best modulation for a given bias voltage. However, the modulation obtained using 78 AA wells is only slightly worse and it occurs at an ideal wavelength of 1.55 mu . Narrow 45 AA wells never yield very good performance. A high contrast can be obtained with a reasonable insertion loss and a low biasing voltage if 1.4 mu m of 78 AA wells or 1.7 mu m of 110 AA quantum wells are used. The spectral performance of these absorbers in an AFPM cavity has been modelled over a 100 nm wavelength range. A contrast of 164:1 (22 dB) for an insertion loss of only 3.95 dB is predicted at 14 V bias. The performance of AFPM devices at very low biasing voltages around 5 V is also detailed.