Patent attributes
A fiber laser device includes a laser pump for irradiating a laser beam, an optical component, an optical fiber and an optical sensor. The optical component has a first and a second output end, wherein a portion of the laser beam is output from the first output end and another portion of the laser beam is output from the second output end. The optical fiber including a core and a cladding layer is optically coupled between the laser pump and the optical component. A inclined angle θ of the first output end satisfies the following relations that θNA/2≦θ≦θNA, and θNA=sin−1(NA·ncladding/ncore), where NA is numerical aperture of optical fiber, ncore is refractive index of the core, and ncladding is refractive index of the cladding layer. The optical sensor is disposed at a light-transmission path of the laser beam reflected by the first output end.