A low power or passive optical apparatus provides temperature control of dynamic thermooptic devices and temperature-sensitive optical devices formed on the same substrate. The optical apparatus includes a variable heat transfer device with a conductive heat transfer component (e.g., heat pipe) and a heat-conductive interface component (e.g., heat sink) to exchange thermal energy with an external environment. In one embodiment, the heat pipe has a variable resistance and the heat sink has a fixed thermal resistance. In a second embodiment, the heat pipe has a fixed resistance and the heat sink has a variable thermal resistance. In another embodiment both the heat pipe and heat sink have variable thermal resistance. In another embodiment, the optical apparatus further includes a thermoelectric cooler and the variable heat transfer device (e.g., variable heat pipe and/or heat sink) is used to reduce the temperature range over which said thermoelectric cooler operates, resulting in a lower power requirement for the thermoelectric cooler.