An optical modulator prepared by silicon micromachining and thermal bonding

An optical modulator using silicon micromachining and thermal bonding is reported. It consists of a pn junction with an optical cavity formed by wafer bonding between n-type and p-type silicon. The cavity is prepared by a thin n-type silicon membrane covering a step with well-controlled dimensions in p-type silicon. Light transmitted through or reflected by the device can be modulated by a second light source with shorter wavelength.