Researchers at Stanford University have developed a solid-state optical modulator made of silicon and germanium described as a major breakthrough in optoelectronics. The discovery promises a small, low-cost means of converting light beams into data streams on chip at high rates.Conventional wisdom held that a germanium-based modulator was impossible. The key to the discovery was in understanding how the "Stark" effect, which occurs when a strong electric field causes an atom to change a wavelength of light, can be made to work in materials compatible...