Photon counting detector package optimized for laser time transfer with sub‑picosecond limiting precision and stability

The laser time transfer ground to space is an attractive technique to compare the ultra-stable clocks on ground and in space. The photon counting approach enables to reduce significantly the systematic errors of the measurement chain. For the space mission nominated for the next decade the precision and long term detection delay stability requirements are on sub-picosecond level. We have developed a new SPAD detector package for laser time transfer ground to space with extremely high timing precision and stability. It is based on 100 μm or 200 μm diameter K14 series SPAD chips. The device presented is primarily dedicated for a ground segment of the laser time transfer instrument chain. Applying such a detector the limiting precision of laser time transfer characterized by time deviation TDEV is well below 100 fs. The long term timing stability is better than 1 ps over days of operation. The detector package is constructed on a basis of electronics components for which the space qualified equivalents are available. The device construction, tests and results will be presented in detail.