Design of a sub-terahertz sensor using the electro-optic effect in a semiconductor microcavity

We present design guidelines for a sub-terahertz (THz) sensor based on a semiconductor microcavity probed by transmission using 1.5 μm light. A 3λ cavity made of an InAs/GaAs quantum dot superlattice (QDSL) structure sandwiched between two GaAs/AlAs distributed Bragg reflectors is considered, and we predict a THz detection limit of ∼10 kV/m for a cavity quality factor of ∼1000 and an electro-optic coefficient of the cavity layer that is 20 times larger than that of GaAs. We show that such a sensor can provide relatively large phase-shift signals even when the QDSL structure does not extend over the entire cavity region; it is sufficient to form a relatively thin QDSL region at each antinode of the optical electric field inside the cavity.