The camel diode is a three layer majority carrier device with an interior layer sufficiently thin so that it is depleted of carriers at all values of bias voltage. The current flow is controlled by a potential barrier in the bulk of the semiconductor, the height of which can be controlled by free carriers trapped in the potential minimum. They will be generated optically within the space charge layer and the adjacent diffusion region. Basic theoretical considerations and first experimental results, which exhibit a gain of values of up to 500, are presented.