Embodiments include an apparatus including an optical fiber having a proximal end and a distal end. The distal end of the optical fiber has a surface configured to emit energy transverse to a longitudinal axis of the optical fiber. The apparatus also includes a tube including a channel, and the distal end of the optical fiber is disposed in the channel of the tube. The apparatus further includes an element disposed at a distal end of the tube such that a pocket is formed in the channel of the tube between the element and the distal end of the optical fiber.