Feedhorn antennas for up GREAT high performance feedhorns

Feedhorn antennas for up. GREAT • high performance feedhorns – smooth-walled spline profile (Granet 2004, Zeng 2010) – optimized beam characteristics in 3 D-EM modeller and fabricated by electroforming (Radiometer Physics Gmb. H) – 1. 9 – 2. 5 THz (wideband), 4. 7 THz – specs FPBW(-10 d. B)=19. 5°, G=25 d. Bi 4. 7 THz feedhorn M 1. 6 0. 7 mm aperture circ. to rect. WG transition R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT 2. 4 mm IRMMW-THz 2014 Tucson 1

Feedhorn-mixer interface • xxx 4 mm R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 2

Fabrication of waveguide devices Nb. N deposition @ 1000°C R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 3

Fabrication of waveguide devices • few nm thin superconducting microbridge layer is crucial for HEB performance characteristics – e. g. IF bandwidth, LO power consumption – Nb. N now replaces Nb. Ti. N as superconductor (higher IF) • 2 µm thin membrane substrates – Si now replaces Si. N (higher IF) – SOI wafer used for processing – DRIE definition for substrate shaping • fabrication split into frontside and backside processing – DC IV characterisation in-between • all fabrication incl. Nb. N layer in-house R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 4

R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 5

Device fabrication frontside R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 6

Device ready for IV tests R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 7

SOI wafer • 348 HEB plus test devices • IV characterization before backside processing • backside processing on individual sections 30 mm after frontside processing diced for IV characterization R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 8

DC device characterization • device uniformity across wafer crucial for equal LO power consumption in array receiver RT 120 Ohm IV 80 Ohm 35 of 36 devices after front side processes R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT 80 Ohm 120 Ohm 18 devices after front side processing IRMMW-THz 2014 Tucson 9

Device fabrication backside R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 10

Fishing for devices … R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 11

4. 7 THz waveguide HEB device IF output and DC connection RF input section m µ 0 25 1 R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 12

4. 7 THz waveguide HEB device d a e ml bea RF part with waveguide, probe antenna, transmission line chokes and HEB microbridge R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 13

microstrip transmission line with impedance matching and choke sections waveguide window waveguide probe antenna l/4 high Z line to ground alignment window HEB microbridge 3 µm electroplated Au beamlead 2 µm Si membrane substrate RF section of 4. 7 THz HEB device R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 14

HEB microbridge with contacts 5 nm x 300 nm x 3600 nm x 5 nm Nb. N microbridge R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 15

Device mounted and contacted HFA device 750 µm R 2/A-28. 1 P. Pütz et al. : Waveguide HEB mixers for up. GREAT IRMMW-THz 2014 Tucson 16