The authors demonstrate coupling at 1.3μm between single InAs quantum dots (QDs) and a mode of a two dimensional photonic crystal (PhC) defect cavity with a quality factor of 15 000. By spectrally tuning the cavity mode, they induce coupling with excitonic lines. They perform a time integrated and time-resolved photoluminescence and measure an eightfold increase in the spontaneous emission rate inducing a coupling efficiency of 96%. These measurements indicate the potential of single QDs in PhC cavities as efficient single-photon emitters for fiber-based quantum information processing applications.

Photonic Crystal (PhC) nanocavities have shown to be good candidates to enhance the spontaneous emission (SE) rate of an emitter into a specific cavity mode (Purcell effect) and allow the implementation of single photon sources. We report our progress in the fabrication of PhC nanocavities with high quality factors in the 1300 nm region. PhC nanocavities with H1 and L3 geometries were characterised in a microphotoluminescence set-up at room temperature. The quality factor was studied as a function of lattice constant a, filling factor, lateral displacement and radius of holes adjacent to the cavity in the L3 geometry. A Q = 3000 is measured in a L3 cavity with filling factor = 35%, a = 311 nm, displacement of 0.125 a and r = 0.53r 0 .2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction The discrete character of electronic states in semiconductor quantum dots can be exploited to control the statistics of the emitted light, and in particular to generate single photons on demand. Single photon sources may improve the bit rate and maximum transmission distance of quantum key distribution (QKD) systems, if high efficiency (> 10%) and statistical purity (g(2)(0)<<1) are achieved at fibre-communication wavelengths. Recently, single photon emission at 1300 nm from single excitons in QDs has been achieved [1][2][3], however the efficiency is still low ( <1%). The photon extraction efficiency may be increased by integrating an optical nanocavity around the QD. This idea is based on the Purcell effect i.e. the capability to modify the spontaneous emission (SE) rate of an emitter when it is placed inside a cavity. Purcell demonstrated that an optical nanocavity with quality factor Q and effective modal volume V, is able to enhance the SE rate of a factor [4]:

For time-sensitive networks, as in the context of IEEE TSN and IETF Detnet, cyclic dependencies are associated with certain fundamental properties such as improving availability and decreasing reconfiguration effort. Nevertheless, the existence of cyclic dependencies can cause very large latency bounds or even global instability, thus making the proof of the timing predictability of such networks a much more challenging issue. Cyclic dependencies can be removed by reshaping flows inside the network, by means of regulators. We consider FIFO-per-class networks with two types of regulators: perflow regulators and interleaved regulators (the latter reshape entire flow aggregates). Such regulators come with a hardware cost that is less for an interleaved regulator than for a perflow regulator; both can affect the latency bounds in different ways. We analyze the benefits of both types of regulators in partial and full deployments in terms of latency. First, we propose Low-Cost Acyclic Network (LCAN), a new algorithm for finding the optimum number of regulators for breaking all cyclic dependencies. Then, we provide another algorithm, Fixed-Point Total Flow Analysis (FP-TFA), for computing end-to-end delay bounds for general topologies, i.e., with and without cyclic dependencies. An extensive analysis of these proposed algorithms was conducted on generic grid topologies. For these test networks, we find that FP-TFA computes small latency bounds; but, at a medium to high utilization, the benefit of regulators becomes apparent. At high utilization or for high line transmission-rates, a small number of per-flow regulators has an effect on the latency bound larger than a small number of interleaved regulators. Moreover, interleaved regulators need to be placed everywhere in the network to provide noticeable improvements. We validate the applicability of our approaches on a realistic industrial timesensitive network.

Google QUIC accounts for almost 10 % of the Internet traffic and the protocol is not standardized at the IETF yet. We distinguish Google QUIC (GQUIC) and IETF QUIC (IQUIC) since there may be differences between the two. Both Google and IETF versions run over UDP and cannot be split the way satellite systems usually do with TCP connections. The need for adapting any-QUIC parameters needs to be evaluated. Since GQUIC is available, we analyze its behavior over a satellite communication system. In our evaluations, GQUIC quick connection establishment does not compensate an inappropriate congestion control. The resulting page downloading time doubles when using GQUIC as opposed to the performance with optimized split TCP connections. This paper concludes that specific tuning are required when any-QUIC runs over a high BDP network.

This article proposes a discussion on the strengths, weaknesses, opportunities and threats related to the deployment of QUIC end-to-end from a satellite-operator point-of-view. The deployment of QUIC is an opportunity for improving the quality of experience when exploiting satellite broadband accesses. Indeed, the fast establishment of secured connections reduces the short files transmission time. Moreover, removing transport layer performance enhancing proxies reduces the cost of network infrastructures and improves the integration of satellite systems. However, the congestion and flow controls at end points are not always suitable for satellite communications due to the intrinsic high bandwidth-delay product. Further acceptance of QUIC in satellite systems would be guaranteed if its performance in specific use-cases is increased. We propose a running code for an IETF document, and based on an emulated platform and on open-source software, this paper proposes values of performance metrics just as one piece of the puzzle. The final performance objective requires consensus among the different actors. The objective should be challenging enough for satellite operators to allow QUIC traffic but reasonable enough to keep QUIC deployable on the Internet.