Logarithmically graded quantum well far‐infrared modulator

We have designed and fabricated a remotely doped ‘‘logarithmic’’ potential well intended to have a tunable, narrow band absorption at far‐infrared frequencies. A surface gate, epitaxially grown backgate, and contact to the electron gas in the quantum well allow independent control of the absorption frequency and the integrated absorption strength. The resonance frequency is dominated by the well curvature at the potential minimum and can be Stark shifted from ω/2πc=35 cm−1 to a frequency of 125 cm−1 by moving the electron gas through the asymmetric well.