Abstract: Multi-quantum well (MQW) spatial light modulator devices are disclosed that are capable of achieving reasonable quantum efficiencies and high contrast ratios in order to close an optical communication link by resolving the logical on or off state. The device both modulates and detects light through the use of the quantum well design and resonant cavity enhancement. Based on the materials (e.g., InGaAs/InAlAs) and their band structures, this device can be configured to communicate in the eye-safe wavelength range (e.g., 1550±20 nm). The device can be fabricated using standard photolithographic processes such as molecular beam epitaxy (MBE) and inductively coupled plasma (ICP) reactive ion etching (RIE).

Abstract: A semi-covert emergency transmission device and methodology for soldiers and other such personnel requiring pick-up or rescue is disclosed. The device has a flashlight mode and a transmit mode. In flashlight mode, an LED is turned on to provide an illumination source that can be used in numerous applications. In transmit mode, the device uses the same LED to transmit a coded message that includes information relevant to the user. The coded message can be preprogrammed and stored in the device, or translated in real-time. The transmit mode is further configured so as to confirm that the intended user is the one requesting the transmission of the coded message. The light emitted from the LED can be seen for up to a mile or so away by friendly forces or other potential rescuers.