Device: M14 C11 in
STO2 mixer block
Antenna: Twin slot for 1.9 THz
2015-04-10
Measurement date
Xuxiang Liu/Wouter
Results summary and setup information
Optics and LO
Lo frequency
Beam splitter
Dewar window
Heat filter(s)
HEB lens
Air loss
Total optics loss in signal path
Aditional optics: voice coil
Polarizer grid
HDPE lens
1.9 THz Gas laser (CH2F2)
3um mylar (-0.2dB)
1.2 mm UHMW-PE (-1dB)
QMC metal mesh W907 @ 4K, open @ 77K
(-0.2 dB)
10mm Ø coated elliptical lens (-1dB)
20 cm, ~30% humidity (-0.2 dB)
-2.6 dB
-
IF circuitry
4K
300K
Total gain:
HEB;Bias T; CITLF4 SN124 (42 dB), -6 dB attenuator;
Miteq AMF-4D-100600-23D (38dB);tunable K&N filter (-1 dB) (or YIG filter),
-10 dB attenuator, Miteq AFS3-00101200-35-ULN (27 dB), fast Agilent IF
power head.
90 dB
Device
R300K
Ic
Tc
Antenna
Device size
128.3 Ω
116 µA
Twin slot for 1.9 THz
1.5 x 0.2 um / SiO2
Results
Phot / Pcold / Pshorted /
U factor
DSB mixer gain (including all optical losses)
Y-factor at optimum bias and LO
DSB Trec
Absorbed LO power at optimum pumping
1.1 dB
643 K
126 nW
Using a FIR cryostat, so the mixer block temperature is assumed to be 4.2-4.3 K, but
not measured
1. System Setup Information
Optics:
FIR Laser→Lens→Voice coil / polarizer →Beam splitter→Cryostat
Setup + device images
2. I-V Curves and pump power
I-V curves of un-pumped and optimal pumped situation are shown for a bias voltage sweep of 10 to 10mV. The optimal pumped power is about 125.9 nW
The IV curves for varying bias currents, 0.8mV are shown as below:
3. DSB Trec using variable LO
Measurements of DSB receiver noise temperature using a fixed bias voltage and varying LO
power are shown below. LO power is varied using the swing arm voice coil. Y-factor and
receiver noise temperature at optimum are 1.1 dB and 643 K respectively.
The optimal bias point is (0.8mV, 0.0256mA)
Noise temperature versus bias point:
4. IF Noise.
The IF noise is measured from 0 to 7 GHz, at the optimal bias point (0.8mV, 0.025mA). There is
a ripple in the data. This is attributed to the mismatch in the impedances between the HEB and
IF circuit. The ripple is time independent, that has been checked.
We also measure the IF noise at (0.6mV, 0.023mA):
(1mV, 0.027mA):