Our balanced homodyne detection (BHD) systems have outstanding specifications and are optimized for measuring squeezed states of light and weak signals carried by cw laser light. They exhibit very low electronic dark noise and thus a high dark noise clearance of more than 20dB with 10mW of local oscillator power in the MHz frequency range. This enables the user to directly detect at least 10 dB of squeezed light. The common mode suppression ratio is more than 50 dB at 1MHz.
The BHD system comes with an electronic mixing path for the demodulation of control signals and the generation of error signals with the purpose to lock the relative phases of the squeezed vacuum and the BHD local oscillator. This way extended measuring periods with a stably controlled squeezed quantum noise are achieved. The modulation/demodulation frequency is typically set between 1 and 80 MHz according to customer requirements.
At 1064 nm and 1550 nm, we offer BHD systems with more than 95% quantum efficiency. BHD systems optimized for other wavelengths are available on request.