A temperature-controlled system for testing a laser die mounted on a submount is disclosed. The testing system comprises a base having a motor-driven translation platform. The translation platform includes a first testing site having a two-stage temperature control system mounted on a base portion. The temperature control system includes a thermoelectric cooler and a fluid system for circulating a cooling/heating fluid in a circulation block. A mounting portion is also included on the first testing site on which the submount is positioned. The temperature of the mounting portion is controlled by the temperature control system. A probe card having an arm and an electrical contact portion attached to the arm provides a power supply to the submount when the first testing site is aligned with the probe card. An aligner having a lens assembly that is alignable with the first testing site receives an optical signal produced by the laser.