Systems, devices, and methods for determining advancement of a surgical laser fiber in an endoscope and providing interlocking feedback for the surgical laser are disclosed. An exemplary method includes directing light from a distal end of an endoscope to a target, optically detecting an amount of the light reflected from the target, transmitting the optically detected amount of light through a laser fiber extending through a working channel of the endoscope, determining, based on the optically detected amount of light, a position of a distal end of the laser fiber relative to the distal end of the endoscope, and generating a control signal to the surgical laser system to adjust laser emission through the laser fiber.