New mechanism of optical gain in two-dimensional material requires only extremely low input power

Optical gain is a prerequisite for signal amplification in an optical amplifier or laser. It typically requires high levels of current injection in conventional semiconductors. By exploring an intricate balance and conversion of excitons and trions in atomically-thin two-dimensional materials, the authors found a new gain mechanism that requires input power several orders of magnitude lower than in conventional semiconductors. This new gain mechanism could potentially enable lasers to be made wi...