A main object of the present invention is to provide a method for manufacturing a microlens that can easily form a microlens having a smooth shape, in which a maximum thickness position is different from a gravity center position. In the KTP crystal, wavelength conversion is performed to generate a second harmonic pulse laser beam with a two times higher frequency, which long-pulse second harmonic pulse laser beam is in turn output for laser processing such as welding etc. The ribboned polarization-maintaining fiber is manufactured by arranging the polarization-maintaining fibers with an exact pitch width while the end face of the polarization-maintaining fibers are rotationally adjusted so as to have a predetermined plane of polarization and then by fixing and coating a part thereof by and with an adhesive, thereby forming the ribbon portion.