Anti-reflection Coated Pump Dumps

Optical fibers, the backbone of many communication, laser, and amplifier technologies, often need to handle complicated light signals. This sometimes results in unwanted light transmission into the cladding of the fiber and can cause inaccuracies and performance issues. Removing this unwanted light, often referred to as pump light, has always been a challenging task. Traditional approaches included high-index polymer coatings and roughening the cladding's outer surface for such purposes. High-index polymer coatings, prime amongst the traditional approaches, were not entirely efficient or reliable. These coatings, when absorbing the stripped light, melted or even burned at high optical powers, proving unsuitable for high-power applications. Another method, namely roughening the cladding's outer surface, limited the fiber for many applications by making them brittle. Both these methods, although useful, presented significant issues that necessitated an advanced, improved technology.

Technology Description

A device known as a pump dump, also referred to as a cladding mode stripper, expels unwanted light from the cladding of an optical fiber. Traditional pump dumps, involving high-index polymer coatings and roughened outer surfaces of the cladding, have been widely used. This innovative technology overcomes the downsides of the traditional methods by using irregularly distributed, shaped features of less than a micron in size. These minuscule features do not absorb light, thus they do not burn or melt even under high optical powers. Importantly, they are small enough to avoid making the fiber brittle, resolving the key issue with the traditional approach and making them highly effective for dumping high-power pump beams from the cladding of fiber amplifiers and fiber lasers.