Recently the “lab-on-fiber” technology has been rapidly developed and demonstrated in several interdisciplinary application fields. It expressed as multifunctional photonic devices and components arising from the integration onto optical fibers of different materials at micro and nano-scale with suitable physical, chemical and biological properties. In this paper, a briefly introduction about the concept of “lab-in/on-fiber” has been given. Then, we concentrate to discuss in-fiber waveguides integration technology which provides an infrastructure for “lab-in/on-fiber”. Finally, we give several examples to show each unique experimental lab-in/on-fiber in different application fields and to demonstrate how it is possible to exploit the micro laboratories platforms.