A system for holding optical fibers in a predefined orientation and cleaving the optical fibers, the system comprising: a substrate structure comprising: a substrate top surface; and a substrate front edge; a groove along the substrate top surface, the groove extending from the substrate front edge in a direction parallel to the predefined orientation, the groove being dimensioned to receive a portion of a bare optical fiber; and a transverse structure on the top surface, the transverse structure crossing the groove at an angle, the transverse structure for receiving ultraviolet light curable material, the UV-curable material for securing the end of the bare optical fiber within the groove, a substrate rear wall, a sub-mount structure comprising: a recess for holding the substrate structure therein, the recess comprising: a recess front edge; and a recess rear wall characterized in that: the sub-mount structure further comprising: a sub-mount stop located at the recess front edge; and a plunger hole located in the recess rear wall; the substrate structure further comprising: a substrate bottom structure for abutting against the sub-mount stop; and a spring plunger insertable into the plunger hole, the spring plunger for applying a force against the substrate rear wall, the spring plunger and the sub-mount stop cooperatively securing the substrate structure in the recess. a substrate structure comprising: a substrate top surface; and a substrate front edge; a substrate top surface; and a substrate front edge; a groove along the substrate top surface, the groove extending from the substrate front edge in a direction parallel to the predefined orientation, the groove being dimensioned to receive a portion of a bare optical fiber; and a transverse structure on the top surface, the transverse structure crossing the groove at an angle, the transverse structure for receiving ultraviolet light curable material, the UV-curable material for securing the end of the bare optical fiber within the groove, a substrate rear wall, a sub-mount structure comprising: a recess for holding the substrate structure therein, the recess comprising: a recess front edge; and a recess rear wall a recess front edge; and a recess rear wall characterized in that: the sub-mount structure further comprising: a sub-mount stop located at the recess front edge; and a plunger hole located in the recess rear wall; the substrate structure further comprising: a substrate bottom structure for abutting against the sub-mount stop; and a spring plunger insertable into the plunger hole, the spring plunger for applying a force against the substrate rear wall, the spring plunger and the sub-mount stop cooperatively securing the substrate structure in the recess. the sub-mount structure further comprising: a sub-mount stop located at the recess front edge; and a plunger hole located in the recess rear wall; a sub-mount stop located at the recess front edge; and a plunger hole located in the recess rear wall; the substrate structure further comprising: a substrate bottom structure for abutting against the sub-mount stop; and a spring plunger insertable into the plunger hole, the spring plunger for applying a force against the substrate rear wall, the spring plunger and the sub-mount stop cooperatively securing the substrate structure in the recess. a substrate bottom structure for abutting against the sub-mount stop; and a spring plunger insertable into the plunger hole, the spring plunger for applying a force against the substrate rear wall, the spring plunger and the sub-mount stop cooperatively securing the substrate structure in the recess.