Fiber-Coupled Microsphere Laser at Wavelength of 1.55 µm

The figure depicts the laboratory setup of an optical-fiber-coupled microsphere laser with an output in the 1.55-µm wavelength band used in some communication systems. This laser offers the obvious advantages of compactness and simplicity. In addition, as consequences of the high resonance quality factor (Q) and smallness of the microsphere, it also offers the non-obvious advantages of a high degree of spectral purity and a low threshold power level. This laser could be useful as a source of highly coherent infrared light or, if operated in a subthreshold regime, as a low-noise front-end amplifier in optical communication. Alternatively, with the addition of active mode locking, this laser could be the core of an ultra-compact optoelectronic oscillator that would generate a light signal modulated by a microwave signal according to the principle described in "Closed-Loop Microsphere Laser for Optoelectronic Oscillator" (NPO-20597),NASA Tech Briefs, Vol. 25, No. 9 (September 2001), page 14a.