A novel multi-junction detector device and method of manufacture is disclosed, which includes providing a housing, at least one system mount body positioned within the housing, forming at least one beam dump region in the system mount body in optical communication with at least one first detector having a first wavelength responsivity range positioned on the system mount body and at least one second detector having a second wavelength responsivity range positioned on the system mount body in optical communication with the first detector. An arcuate shape, an arcuate shape of varying radius, a polygonal shape or a polyhedral shape may be formed on at least one mount body wall in the beam dump region. The method may also comprise depositing at least one reflectivity enhancing material onto the mount body wall. The method may further comprise depositing an energy dissipating material on the mount body wall.