A spectroscopic assembly is provided. The spectroscopic assembly includes a thermal isolation platform, a gas reference cell encasing a gas and attached to the thermal isolation platform, the gas reference cell having at least one optically-transparent window, and at least one heater configured to raise a temperature of the encased gas. When a beamsplitter is configured to reflect a portion of an input optical beam emitted by a laser to be incident on the at least one optically-transparent window of the gas reference cell, the reflected portion of the input optical beam is twice transmitted through the gas. When a detector is configured to receive the optical beam twice transmitted through the gas, a feedback signal is provided to the laser to stabilize the laser.