Patent ID: 7515776

Claim:
An optical modulator comprising: an active region including one or more semiconductor quantum well structures, each comprising: a well layer having a composition Si 1-x Ge x , wherein x is greater than about 0.7 and is selected such that an energy-momentum relation E w (k) of the lowest energy conduction band of the well layer at k=0 has a local minimum at k=0; a first barrier layer having a composition Si 1-y Ge y and disposed on a first side of the well layer, wherein y<x; and a second barrier layer having a composition Si 1-z Ge z and disposed on a second side of the well layer opposite the first side, wherein z<x; a temperature control element disposed in proximity to the active region, capable of maintaining the active region at a predetermined operating temperature other than room temperature; wherein an electric field responsive to an electrical input to the device is present in the active region; whereby an optical response of the quantum well structure is altered by the electrical input; wherein a wavelength dependence of the optical response depends on the predetermined operating temperature.