Reaching GHz single photon detection rates with HgCdTe avalanche photodiodes detectors

Abstract

In the present communication, the characterization results of an in-house developed four-quadrants detection module based on HgCdTe APDs and a Si-CMOS ROIC pre-amplifier is discussed. The module has been designed to be employed as high data rate ground-segment detector for 1.55 μm long-distance free-space optical communication links in the framework of a project funded by the European Space Agency. The detector is characterized by a multiplication gain in excess of M = 150, a ROIC input referred noise of Ne = 45 electrons rms and a measured bandwidth of BW = 450 MHz. These characteristics enable the linear-mode detection of meso-photonic states ranging from tens of photons per pulse down to the single-photon level at high count rates exceeding 500 MHz per quadrant (and 2 GHz if the signal is dispatched over all four-quadrants). For the present module, the performance for PPM and OOK modulation formats was estimated and its potentiality for long-distance free-space optical communications employing these modulation formats was validated. In particular, for the PPM format, a detection probability of 0.9 and a false alarm probability of 10 -2 , a minimum PPM slot width of 500 ps and a temporal jitter with a FWHM ~ 160 ps were estimated, for an incident photonic state with 10 photons/pulse. The potentiality of the detector for 625 Mbps OOK modulation format was also evaluated and compared with a quantum limited situation. In this case, a -3.9 dB penalty from the quantum limited BER was obtained. A new generation of detectors is currently in development, which is expected to further improve the performance.

HgCdTe APD detector module for deep space optical communications

“…The input referred noise level in photons, estimated by the ratio of the voltage noise and the fast signal amplitude response of the detector, is close to NEPh~100 photons on each channel. This value is higher than the one observed in the previously characterized devices, NEPh~60 photons [8]. The increase noise can be explained by use of different optical coupling in the previously reported measurement, in which the light was focused onto the detector using a lens with a smaller focal distance and without the use of a micro-lens.…”

“…These measurements have shown that the detectors enables down to single photon detection with a high quantum efficiency and low excess noise at a record high detection rate, in excess of 500 MHz, and with a dark count rate of 500 kHz. These results shows on the strong potential of this technology to detect and process information at a single photon signal level [4], [8].…”

“…A specifically designed resistive feed-back trans-impedance amplifier (RTIA) with 4 channels, termed CL110, was designed and procured at CEA/Leti with this objective. The first characterization of this amplifier have shown that this approach have enabled a bandwidth in excess of 400 MHz combined with an input noise of 40 electrons and have enabled single photon detection at an APD gain of about 200 [4], [8]. As a comparison, the input noise of a deported RTIA amplifier is typically in excess 300 electrons and would require an APD gain of 1000 to reach single photon detection capacity.…”

“…These events will increase the false alarm rate and limit the use of the detector for higher order ppm modulation schemes. The performance of the detector module have been estimated for the system performance parameters given in Table 2 by fitting the observed pulses with a Gaussian function to estimate the amplitude and instant of detection of each pulse, as detailed in [8]. The resulting data show that the observed performance is slightly below the requirements in terms of sensitivity and temporal resolution.…”

Free-Space Optical Data Receivers with Avalanche Detectors for Satellite Downlinks Regarding Background Light

“…Overviews of practically achieved RFE sensitivities can be found in [34] on p. 330 and in [35] (Table 3). An even higher sensitivity has been reported by an alternative APD semiconductor material, HgCdTe, and commercial devices for FSO communication applications might soon be demonstrated [36,37].…”