Tunable fiber Bragg gratings at 1.3 µm to improve the characterization of InAs Quantum Dot emission

Single self-assembled semiconductor quantum dots (QDs) are one of the most promising candidates of versatile photon sources in quantum information technologies [1]. Nevertheless, the characterization of their performance still represents a matter of concern due to the low detection efficiency and signal to noise ratio of standard detectors based on InGaAs Avalanche Photodiodes (APD) at long wavelengths (1000 -1650 nm). Careful engineering of the optical loss in the path from source to detector is necessary to maximize the overall detection yield. We have demonstrated a novel instrumentation concept based on a tunable Fibre Bragg Grating (FBG) filter, which permits the time resolved analysis of single quantum dot emission at telecom wavelengths. We fabricated a 1.3-?m band FBG filter with a bandwidth similar to that of conventional grating monochromators, and whose central wavelength can be tuned in a band of more than 4 nm. The FBG reduces the typical optical losses of the monochromator filtering close to two orders of magnitude. With this technique, conventional InGaAs APD single photon detectors can be used even with no synchronization requirements to manage photons emitted by single QDs.