Layout of the mid-infrared characterization testbench and its components. The abbreviations are as follows: SCS, supercontinuum source; BBS, blackbody source; AC, achromat; AP, aperture; L′, broadband filter; PH, pinhole; and BS, beam splitter. M1 is the fixed mirror. M2, M3, and M4 are the movable mirrors with delay lines. PL is the mid-infrared linear polarizer. The HeNe Laser is the metrology laser used to calibrate the delay lines. The photonic chip contains the 4T-nullers. Top inset: spectral profile of the SCS measured before the photonic chip.