Refractive shielding was a deflector shield stealth technology used by the Devore Imperium of the Delta Quadrant, which allowed a vessel to remain invisible to conventional sensors unless compensated for.
In 2375, Devore inspector Kashyk showed the crew of the USS Voyager how to penetrate their refractive shielding, in an apparent attempt to defect from the Imperium and assist a group of Brenari refugees in escaping from Devore territory. It was eventually discovered by Captain Janeway, however, that Kashyk's defection was simply a ruse to locate a wormhole being used by the refugees to escape. During Kashyk's attempt to destroy the wormhole, he found that he had been misled as to the wormhole's true location, while the refugees escaped in two of Voyager's Class 2 shuttles, which had been equipped with refractive shielding in order to escape detection of the Devore warships. (VOY: "Counterpoint")