The illumination source employs different technologies, ranging from lamps to semiconductor light emitting diodes (LEDs) or lasers. The lamp, while straight-forward, is broad-band, bulky, and generally inefficient.   The main wavelengths of interest for illumination are around 808nm, 976m, 1064nm, and 1550nm. The 808nm region offers the best responsivity for …

The race to conquer the quantum domain is among the most fiercely competitive in today’s world of technology. One important quantum technology is Quantum key distribution (QKD), that establishes highly secure keys between distant parties by using single photons to transmit each bit of the key.   Quantum cryptography is unbreakable …