Patent ID: 6920158

Claim:
An optical module comprising: a laser diode that emits a front laser beam towards a front side thereof and back laser beam towards a back side thereof; a lens that focuses the front laser beam; a feedback unit that reflects a part of the front laser beam that is focused by the lens, and passes or absorbs the rest of the front laser beam; an optical fiber that transmits the front laser beam passed by the feedback unit; and a photodiode that receives the back laser beam and outputs a current proportional to the amount of the back laser beam, wherein the feedback unit comprises a coating provided on an end surface of the optical fiber, wherein: a deviation of a focusing point of the laser beam input to an end surface of the optical fiber causes a relative chance in an amount of the laser beam coupled to an end surface optical fiber and causes a relative change in the current of the photodiode, and the relative change in the current of the photodiode resulting from the deviation is at least one sixth of the relative change in the amount of the laser beam coupled to the end surface optical fiber resulting from the deviation.