Characterization of a correlated, non-degenerated photon source

AGUSTINA G. MAGNONI; LAURA T. KNOLL; IGNACIO H. LOPEZ GRANDE; MIGUEL A. LAROTONDA

San Pablo

Workshop; Laser frontiers: SPSAS+SWIECA; 2018

FAPESP - IPEN

We present the work in progress of a synchronized photon source in the telecom range, based on theprocess of Spontaneous Parametric Downconversion (SPDC) in a periodically poled KTP nonlinear crystal(PPKTP). This device has two main components: a source of correlated photon pairs and a time multiplexingsystem that synchronizes one of the photons with a clock tick, using temporal information from the heraldphoton.The first component is already implemented and characterized: a 532 nm single mode laser (1 MHzbandwidth) pumps the nonlinear crystal. Correlated photons are generated at 1550 nm ("signal") and at 810nm ("idler") by SPDC. The idler photon is used as a herald. We have studied the performance of the systemfor different pump powers, measuring single counts at the idler beam, coincidences and the coincidence-toaccidental ratio (CAR). Also, we characterized coupling and heralding efficiencies (obtaining an 11%). Theoutput spectra was measured for different crystal temperatures.We are currently working on the time multiplexing system. The aim is to synchronize the 1550 nm photon arrival with an external clock's tick, in order to obtain a deterministic single photon source. This approach consists in using the timing information in the detection of the idler photon to modify the signal's path so that it exits the system at an specific time. The path modification will be done by a series of fast optical switches connected to a binary division fiber network. We will present a detailed analysis and a simulation of the source statistics including losses and non-ideal components.