Method and apparatus for optically modulating light through the back side of an integrated circuit die

A method of modulating a light beam, the method comprising the steps of:

• diffracting the light beam received through a back side of an integrated circuit die and through a diffraction grating including a metal oxide semiconductor (MOS) transistor structure including a gate, a drain region, a source region and a channel disposed between the drain region and the source region to generate a diffracted light beam, the drain and source regions commonly coupled so as to form a capacitor;
• modulating a phase of a portion of the diffracted light beam that passes through the channel in response to a signal;
• and
• deflecting the diffracted light beam back out the back side of a semiconductor substrate.

A method of providing an optical modulator, the method comprising:

• providing a diffraction grating including a metal oxide semiconductor (MOS) transistor structure in a semiconductor substrate of an integrated circuit die, the MOS transistor structure including a gate, a drain region, a source region and a channel disposed between the source region and the drain region;
• commonly coupling the drain and source regions so as to form a capacitor;
• coupling the gate to receive a signal to change charge in the channel in response to the signal;
• and
• disposing a deflector in the integrated circuit die proximate to the MOS transistor structure to deflect a light beam received through the back side of the semiconductor substrate through the MOS transistor structure to create a modulated light beam.