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 (UV) 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 (UV) 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 . <EOS>