Fabry--Perot reflectance modulator for 1. 3 [mu]m from (InAlGa)As materials grown at low temperature

We report the first all-semiconductor Fabry--Perot-cavity reflectance modulators operating at wavelengths of 1.32--1.33 [mu]m. These devices were grown on a GaAs substrate using an intermediate, linearly graded InGaAs buffer layer terminating in an In[sub 0.33]Ga[sub 0.67]As layer. The Bragg reflector stacks of the Fabry--Perot structure are composed of InGaAs and InAlAs layers lattice matched to the buffer, and the active cavity region is an In[sub 0.4]Ga[sub 0.6]As/In[sub 0.26]Al[sub 0.35]Ga[sub 0.39]As strained-layer superlattice. The key to obtaining device-quality material was low temperature growth ([similar to]400 [degree]C) of the entire structure. For a device with a 0.38-[mu]m-thick active region and a 4 dB insertion loss, we obtained a contrast ratio of [similar to]3:1 at 4 V bias.