Photon noise limited performance over an octave of bandwidth of kinetic inductance detectors for sub-millimeter astronomy

We present the development of background limited kinetic inductance detectors (KIDs) for THz astronomy applications to be used in space based observatories. The THz radiation is coupled to the KID via a leaky wave antenna covering the frequency range from 1.4 to 2.8 THz. We have developed a hybrid niobium titanium nitride/aluminium (NbTiN/Al) KID, fabricated on a silicon (Si) substrate, in which the leaky wave antenna and absorbing section of the KID are fabricated on a suspended silicon nitride (SiN) membrane. The radiation is coupled to the leaky wave antenna with a Si lens placed on top of it at a distance of 3μm. We observe photon noise limited performance both in the phase and amplitude readout simultaneously. Both the optical efficiency and the antenna beam patterns have been measured with excellent agreement with the simulations, and the measured FTS shows a large frequency range (over an octave), only limited by the optical filters placed in the setup.