Low Noise 1 THz–1.4 THz Mixers Using Nb/Al-AlN/NbTiN SIS Junctions

Karpov, A.; Miller, David; Rice, F.; Stern, J. A.; Bumble, B.; Leduc, H. G.; Žmuidzinas, J.

doi:10.1109/tasc.2007.898277

Cited by 50 publications

(29 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…At THz frequencies, T rcvr values of 350-450 K at 1-1.4 THz have been achieved with superconductor-insulator-superconductor (SIS) mixers, 30 and approximately 35-40 K has been achieved at 230 GHz for ALMA Band 6 receivers (ALMA Memo #553, see http://www.alma.nrao.edu) in the 230 GHz atmospheric window. Even so, these numbers are significantly higher than quantum-limited performance, and so further improvement can be expected.…”

Section: B Sensitivity Of Pulsed Ft Systems At Thz and Mw Frequenciesmentioning

confidence: 99%

Principles and promise of Fabry–Perot resonators at terahertz frequencies

Braakman

Blake

2011

Journal of Applied Physics

View full text Add to dashboard Cite

Fabry-Perot resonators have tremendous potential to enhance the sensitivity of spectroscopic systems at terahertz (THz) frequencies. Increasing sensitivity will be of benefit in compensating for the relatively low power of current high resolution continuous wave THz radiation techniques, and to fully express the potential of THz spectroscopy as source power increases. Improved sensitivities, and thus scanning speeds, will allow detailed studies of the complex vibration-rotation-tunneling dynamics that large molecules show at THz wavelengths, and will be especially important in studying more elusive, transient species such as those present in planetary atmospheres and the interstellar medium. Coupling radiation into the cavity presents unique challenges at THz frequencies, however, meaning that the cavity configurations common in neighboring frequency domains cannot simply be translated. Instead, novel constructions are needed. Here we present a resonator design in which wire-grid polarizers serve as the input and output coupling mirrors. Using this configuration, Q-factors of a few times 10 5 are achieved near 0.3 THz. To aid future investigations, the parameter space that limits the quality of the cavity is explored and paths to improved performance highlighted. Lastly, the performance of polarizer cavity-based Fourier transform (FT) THz spectrometers is discussed, in particular those design optimizations that should allow for the construction of THz instrumentation that rivals and eventually surpasses the sensitivities achieved with modern FT-microwave cavity spectrometers.

show abstract

Section: B Sensitivity Of Pulsed Ft Systems At Thz and Mw Frequenciesmentioning

confidence: 99%

Principles and promise of Fabry–Perot resonators at terahertz frequencies

Braakman

Blake

2011

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…To first order, the broadband response of a heterodyne mixer can be assessed using Fourier transform spectroscopy (FTS; Higgins et al 2014), whereby a monochromatic signal is radiated onto a mixer and the total power response of the mixer is recorded (e.g. de Lange et al 2003;Teipen et al 2005;Karpov et al 2007;Cherednichenko et al 2008). How accurately the total power response measured by the FTS matches the heterodyne sideband ratio is a topic of debate, especially since FTS measurements are usually performed with an unpumped mixer; i.e.…”

Section: For Other Conventionsmentioning

confidence: 99%

Derivation of sideband gain ratio forHerschel/HIFI

Kester

Higgins

Teyssier

2017

A&A

View full text Add to dashboard Cite

Context. Heterodyne mixers are commonly used for high-resolution spectroscopy at radio telescopes. When used as a double sideband system, the accurate flux calibration of spectral lines acquired by those detectors is highly dependent on the system gains in the respective mixer sidebands via the so-called sideband gain ratio (SBR). As such, the SBR was one of the main contributors to the calibration uncertainty budget of the Herschel/HIFI instrument. Aims. We want to determine the HIFI instrument sideband gain ratio for all bands on a fine frequency grid and within an accuracy of a few percent. Methods. We introduce a novel technique involving in-orbit HIFI data that is bootstrapped onto standard methods involving laboratory data measurements of the SBR. We deconvolved the astronomical data to provide a proxy of the expected signal at every frequency channel, and extracted the sideband gain ratios from the residuals of that process. Results. We determine the HIFI sideband gain ratio to an accuracy varying between 1 and 4%, with degraded accuracy in higher frequency ranges, and at places where the reliability of the technique is lower. These figures were incorporated into the HIFI data processing pipeline and improved the overall flux uncertainty of the legacy data from this instrument. Conclusions. We demonstrate that a modified sideband deconvolution algorithm, using astronomical data in combination with gas cell measurements, can be used to generate an accurate and fine-granularity picture of the sideband gain ratio behaviour of a heterodyne receiver.

show abstract

“…These mixers and their development are discussed in detail elsewhere. 7 The ongoing development is expected to significantly reduce the noise temperatures compared to present receivers at these frequencies. It is expected that this development will achieve double side band (DSB) noise temperatures of the order of 3h!/k B for devices operating at less than 1 THz and 6h!/k B above.…”

Section: Receiversmentioning

confidence: 99%