Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Revue de Physique Appliquée

Heterodyne laser radiation detection at 891 GHz using josephson point contacts

T. G. Blaney

Published Jan 1, 1974• 20 citations
Publisher

Abstract

Experiments were carried out to investigate the performance of a heterodyne detector at 891 GHz using a cw hydrogen cyanide laser as the local oscillator and Nb-Nb point contact Josephson junctions as mixing devices. Using a second off-tuned HCN laser as the signal, intermediate frequencies (IF's) up to a few MHz could be studied. Both pre-set and adjustable types of junction were used, and the latter, arranged so that radiation could be directly focussed onto them gave the best ultimate sensitivity. Dependence of the IF power on dc current bias and local oscillator power is described, and compared with simple theory. IF power varied linearly with signal power for signals less than 10-5 to 10-6 W. The mixer conversion efficiency was independent of IF. The sensitivity of the detector was a strong function of junction characteristics and ranged over several orders of magnitude in the junctions studied. Noise at the output was dominated by the room temperature preamplifier with a noise temperature of about 500 K. The smallest observed value for conversion loss of the junction was about 29 dB. This figure includes the signal input matching loss. The best sensitivity of the whole receiving system was equivalent to 1 × 10-17 W/Hz.

DOI
10.1051/rphysap:0197400901027900

Related papers

Heterodyne reception at 891 GHz using a Josephson harmonic mixer and a microwave local oscillator

T. G. Blaney, D. J. E. Knight

The performance of Nb-Nb point-contact Josephson junction mixers was investigated experimentally with signals from a 891 GHz laser. The local oscillator (LO) was provided by the appropriate junction-generated harmonic of either a 74 or 99 GHz klystron. The intermediate frequency (IF) power varied linearly with signal power for signals less than 10 −5 to 10 −6 W. The optimum conversion loss (from 891 GHz to the IF) was not significantly different for the two klystron frequencies used: the lowest useful conversion loss for the whole mixing system including the signal input matching loss, was 42 (±3) dB. This is 10 dB greater than that observed with a 891 GHz laser LO and the same junction apparatus. Conversion loss of the mixer element alone was independent of IF with the latter varied up to 1·2 GHz. The noise at the output of the IF system was usually dominated by that of the transistor preamplifier with a noise temperature of about 500 K. Thus the input signal necessary to give a signal-to-noise ratio of one at the IF was equivalent to 10 −16 W Hz −1 of IF bandwidth. This mixing system, which can be significantly improved, forms the basis of a fully tunable heterodyne receiver for the submillimetre region.

Journal of Physics D Applied Physics•Sep 21, 1974•11 citations

The properties of a heterodyne receiver at 450 GHz using a Josephson point-contact mixer and an external local oscillator

T. G. Blaney, N R Cross, Robert G. Jones

Adjustable niobium Josephson point contacts, mounted in fundamental-mode waveguide cavities, have been used as mixers in an experimental heterodyne receiver with a 450 GHz laser as the local oscillator. It was possible to estimate separately the various factors, such as intrinsic mixer conversion efficiency, mixer noise, and input coupling efficiency that contribute to the overall receiver sensitivity. Mixer performance agreed reasonably well with qualitative predictions of resistively-shunted-junction theoretical models, and there was broad quantitative agreement for some aspects of performance. Spurious, and potentially very misleading non-heterodyne responses to thermal signals were observed under some regimes of applied DC bias and local oscillator power. The lowest overall receiver noise temperature measured was 2100K (double side band), although reduction to 1000K should be possible with quite simple improvements. The intrinsic mixer noise temperatures were usually in the range 500-1000K (single side band), and local oscillator power required by the receiver was usually less than one microwatt. This performance makes these mixers competitive as the basis of very sensitive near-millimetre-wave receivers.

Journal of Physics D Applied Physics•Nov 14, 1982•12 citations

Experiments using a superconducting point-contact harmonic mixer near 1 THz

T. G. Blaney, D. J. E. Knight

Experiments are described in which simple and relatively reliable point-contact Josephson junctions were used to generate and mix harmonics (up to the 50th) of microwave klystron frequencies with emissions from a hydrogen cyanide laser operating at 891 GHz. Data are presented illustrating the variation of the intermediate frequency signal with DC bias current through the junction and incident radiation power levels, and the results compared, where possible, with a simple qualitative theory of Josephson mixing. Details are also given of experiments in which such a mixer was used to phase-lock a klystron to the laser, enabling the laser frequency to be accurately and continuously monitored.

Journal of Physics D Applied Physics•May 21, 1973•23 citations

Frequency conversion with superconducting point contacts operating as oscillator-mixers and its application to the measurement of the linewidth of the Josephson current at very high frequency

G. Vernet, Robert Adde

The Josephson frequency conversion in the millimeter and submillimeter wave region is studied with superconducting Nb-Nb point contact junctions at 4.2 K, using the contact both as the local oscillator and the mixer with intermediate frequencies of 0.1 and 9.2 GHz. Frequency conversion signals are only detected in the latter case with a microwave receiver at 9.2 GHz in a range of Josephson frequencies between 145 and 1 600 GHz. The experiments with intermediate frequency fi of 0.1 GHz indicate for this small value of f i that the observed signals are not related to frequency conversion but noise effects. An analysis of the frequency conversion mechanism in a Josephson junction operated as an oscillator-mixer is proposed which includes the noise effects and also the feedback effects induced in a junction driven by a constant current source. We have then investigated the noise properties up to 450 GHz of superconducting point-contacts using the junction as an oscillator-mixer where the Josephson current is mixed with harmonics of an externally applied signal. The emitted intermediate frequency is detected at 9.2 GHz and its linewidth is measured. In the very high frequency range the dc quasiparticle current dominates in a Josephson weak-link and we compare the corresponding theoretical linewidth calculated by Scalapino with our experimental results.

Revue de Physique Appliquée•Jan 1, 1974•3 citations

Direct 825th harmonic mixing of a 1 GHz source with an HCN laser in a Josephson junction

T. G. Blaney, D. J. E. Knight

Signals near 1 GHz were multiplied in frequency by up to 825 times and mixed with the hydrogen cyanide laser frequency at 891 GHz in point-contact Josephson junctions. The 1 GHz signals were generated by direct multiplication from a 120 MHz quartz-crystal oscillator, and no microwave transfer oscillator was needed. The maximum IF output powers obtained in these and other harmonic mixing experiments (using the same laser) were found to agree quite well with a simple theory which predicts a limit proportional to the square of the frequency being multiplied in the Josephson junction. This provides a criterion for determining the lowest frequency at which to begin multiplication in a Josephson device.

Journal of Physics D Applied Physics•Sep 21, 1974•37 citations

Josephson heterodyne detection at high thermal background levels

Tim Poorter

Point-contact Josephson junctions with a submicron contact diameter have been used as high-frequency mixers (170–220 GHz) under high thermal background conditions. The junction is formed across a full height (0.56×1.06 mm2) waveguide between a 3–5-μm thick Nb whisker and a 0.2-mm diam Nb center conductor of a coaxial line. The best single-side band mixer-noise temperature that was measured is 165 K (± 25%) with a corresponding single-side band conversion efficiency of 0.36±0.03 (a loss of 4.5 ±0.4 dB) at a signal frequency of 185 GHz, including losses in the coupling horn and the waveguide. The performance was measured with the hot-cold source technique. The effects of nonheterodyne response in that situation were investigated in detail. The junctions have been operated in a coherent receiver that can be used on a telescope with only small adaptations. The instantaneous bandwidth of the receiver is about 20 GHz.

Journal of Applied Physics•Jan 1, 1982•27 citations
Experiments were carried out to investigate the performance of a heterodyne detector at 891 GHz using a cw hydrogen cyanide laser as the local oscillator and Nb-Nb point contact Josephson junctions as mixing devices. Using a second off-tuned HCN laser as the signal, intermediate frequencies (IF's) up to a few MHz could be studied. Both pre-set and adjustable types of junction were used, and the latter, arranged so that radiation could be directly focussed onto them gave the best ultimate sensitivity. Dependence of the IF power on dc current bias and local oscillator power is described, and compared with simple theory. IF power varied linearly with signal power for signals less than 10-5 to 10-6 W. The mixer conversion efficiency was independent of IF. The sensitivity of the detector was a strong function of junction characteristics and ranged over several orders of magnitude in the junctions studied. Noise at the output was dominated by the room temperature preamplifier with a noise temperature of about 500 K. The smallest observed value for conversion loss of the junction was about 29 dB. This figure includes the signal input matching loss. The best sensitivity of the whole receiving system was equivalent to 1 × 10-17 W/Hz.
The performance of Nb-Nb point-contact Josephson junction mixers was investigated experimentally with signals from a 891 GHz laser. The local oscillator (LO) was provided by the appropriate junction-generated harmonic of either a 74 or 99 GHz klystron. The intermediate frequency (IF) power varied linearly with signal power for signals less than 10 −5 to 10 −6 W. The optimum conversion loss (from 891 GHz to the IF) was not significantly different for the two klystron frequencies used: the lowest useful conversion loss for the whole mixing system including the signal input matching loss, was 42 (±3) dB. This is 10 dB greater than that observed with a 891 GHz laser LO and the same junction apparatus. Conversion loss of the mixer element alone was independent of IF with the latter varied up to 1·2 GHz. The noise at the output of the IF system was usually dominated by that of the transistor preamplifier with a noise temperature of about 500 K. Thus the input signal necessary to give a signal-to-noise ratio of one at the IF was equivalent to 10 −16 W Hz −1 of IF bandwidth. This mixing system, which can be significantly improved, forms the basis of a fully tunable heterodyne receiver for the submillimetre region.
Adjustable niobium Josephson point contacts, mounted in fundamental-mode waveguide cavities, have been used as mixers in an experimental heterodyne receiver with a 450 GHz laser as the local oscillator. It was possible to estimate separately the various factors, such as intrinsic mixer conversion efficiency, mixer noise, and input coupling efficiency that contribute to the overall receiver sensitivity. Mixer performance agreed reasonably well with qualitative predictions of resistively-shunted-junction theoretical models, and there was broad quantitative agreement for some aspects of performance. Spurious, and potentially very misleading non-heterodyne responses to thermal signals were observed under some regimes of applied DC bias and local oscillator power. The lowest overall receiver noise temperature measured was 2100K (double side band), although reduction to 1000K should be possible with quite simple improvements. The intrinsic mixer noise temperatures were usually in the range 500-1000K (single side band), and local oscillator power required by the receiver was usually less than one microwatt. This performance makes these mixers competitive as the basis of very sensitive near-millimetre-wave receivers.
Experiments are described in which simple and relatively reliable point-contact Josephson junctions were used to generate and mix harmonics (up to the 50th) of microwave klystron frequencies with emissions from a hydrogen cyanide laser operating at 891 GHz. Data are presented illustrating the variation of the intermediate frequency signal with DC bias current through the junction and incident radiation power levels, and the results compared, where possible, with a simple qualitative theory of Josephson mixing. Details are also given of experiments in which such a mixer was used to phase-lock a klystron to the laser, enabling the laser frequency to be accurately and continuously monitored.
The Josephson frequency conversion in the millimeter and submillimeter wave region is studied with superconducting Nb-Nb point contact junctions at 4.2 K, using the contact both as the local oscillator and the mixer with intermediate frequencies of 0.1 and 9.2 GHz. Frequency conversion signals are only detected in the latter case with a microwave receiver at 9.2 GHz in a range of Josephson frequencies between 145 and 1 600 GHz. The experiments with intermediate frequency fi of 0.1 GHz indicate for this small value of f i that the observed signals are not related to frequency conversion but noise effects. An analysis of the frequency conversion mechanism in a Josephson junction operated as an oscillator-mixer is proposed which includes the noise effects and also the feedback effects induced in a junction driven by a constant current source. We have then investigated the noise properties up to 450 GHz of superconducting point-contacts using the junction as an oscillator-mixer where the Josephson current is mixed with harmonics of an externally applied signal. The emitted intermediate frequency is detected at 9.2 GHz and its linewidth is measured. In the very high frequency range the dc quasiparticle current dominates in a Josephson weak-link and we compare the corresponding theoretical linewidth calculated by Scalapino with our experimental results.
Signals near 1 GHz were multiplied in frequency by up to 825 times and mixed with the hydrogen cyanide laser frequency at 891 GHz in point-contact Josephson junctions. The 1 GHz signals were generated by direct multiplication from a 120 MHz quartz-crystal oscillator, and no microwave transfer oscillator was needed. The maximum IF output powers obtained in these and other harmonic mixing experiments (using the same laser) were found to agree quite well with a simple theory which predicts a limit proportional to the square of the frequency being multiplied in the Josephson junction. This provides a criterion for determining the lowest frequency at which to begin multiplication in a Josephson device.
Point-contact Josephson junctions with a submicron contact diameter have been used as high-frequency mixers (170–220 GHz) under high thermal background conditions. The junction is formed across a full height (0.56×1.06 mm2) waveguide between a 3–5-μm thick Nb whisker and a 0.2-mm diam Nb center conductor of a coaxial line. The best single-side band mixer-noise temperature that was measured is 165 K (± 25%) with a corresponding single-side band conversion efficiency of 0.36±0.03 (a loss of 4.5 ±0.4 dB) at a signal frequency of 185 GHz, including losses in the coupling horn and the waveguide. The performance was measured with the hot-cold source technique. The effects of nonheterodyne response in that situation were investigated in detail. The junctions have been operated in a coherent receiver that can be used on a telescope with only small adaptations. The instantaneous bandwidth of the receiver is about 20 GHz.