Keller is best known for her groundbreaking work on Semiconductor Saturable Absorber Mirrors (SESAMs). These devices revolutionized ultrafast laser technology by enabling the reliable and efficient generation of ultrashort laser pulses. This invention has had a profound impact on various fields, including telecommunications, medicine, and materials science.

Keller and her research group have continued to make advancements in ultrafast laser technology, exploring new materials, laser designs, and applications. This includes pushing the limits of pulse duration, power, and repetition rate, enabling new scientific discoveries and technological applications.