\[sec:obs\] and \[sec:datareduc\])]{}. Then, we discuss the detection of point sources (Sect. \[sec:pointsources\]), the observed disk features (Sect. \[sec:disk\]) and the detection limits on putative giant protoplanets with respect to predictions from the literature (Sect. \[sec:detectionlimits\]). Finally, we analyze the sensitivity of the detection limits to the protoplanetary dust opacity considering the presence of gaps opened by putative giant embedded planets (Sect. \[sec:dustopacity\]).

Observations {#sec:obs}
============

SPHERE [@Beuzit2008] is an extreme adaptive optics (AO) instrument dedicated to high-contrast and high-resolution imaging of young giant exoplanets and circumstellar disks. The AO system [@Fusco2006] includes a fast 41$\times$41-actuators wavefront control, pupil stabilization, differential tip tilt [control,]{} and toric mirrors [@Hugot2012] for beam transportation to the coronagraphs [@Boccaletti2008c] and science instruments. [In this paper, we used the near-infrared science instruments, the infrared dual-band imager and spectrograph IRDIS [@Dohlen2008a] and the integral field spectrometer IFS [@Claudi2008; @Antichi2009]. The focal plane masks of the near-infrared coronagraphs are located in the common path and infrastructure of SPHERE, whereas the Lyot stops are located in IFS and IRDIS and are optimized for each instrument.]{}

We observed SAO 206462 on 2015 May 15 UT in the IRDIFS\_EXT mode (Table \[tab:obs\]). In this mode, [IRDIS and IFS]{} are operated 