A nanoelectromechanical tunable laser

The ability to tune the frequency of an oscillator is of critical importance and is a fundamental building block for many systems, be they mechanical or electronic(1,2). However, this very important function is still highly inadequate in optical oscillators, particularly in semiconductor laser diodes(3,4). The limitations in tuning a laser frequency ( or wavelength) include the tuning range and the speed of tuning, which is typically milliseconds or slower. In addition, the tuning is often not continuous and may require complex synchronization of several electrical control signals. In this Letter, we present a new tunable laser structure with a lightweight nanoelectromechanical mirror based on a single- layer, highcontrast subwavelength grating. The high- contrast subwavelength grating reflector enables a drastic reduction of the mirror mass, which increases the mechanical resonant frequency and hence tuning speed(5). This allows for a wavelength- tunable light source with potential switching speeds of the order of tens of nanoseconds and suggests various new areas of practical application, such as bio- or chemical sensing(6-8), chip- scale atomic clocks(9) and projection displays(10,11).