A method and apparatus comprising a signal generator and wires. The signal generator is configured to generate electrical signals. The electrical signals have amplitudes and first phases. The wires are connected to the signal generator. The wires are configured to emit photons having phases in response to receiving the electrical signals. The photons have frequencies based on the amplitudes of the electrical signals and second phases based on the first phases of the electrical signals. The first phases of the electrical signals are selected such that the photons have a desired radiation pattern.