Photonic local oscillator development

Book-Kok Tan

Akitoshi Ueda, Takashi Noguchi, Shin’ichiro Asayama +7 more

Noise at millimeter wavelengths from a photonic local oscillator (LO) is compared with that from a Gunn oscillator using a low-noise superconductor-insulator-superconductor (SIS) receiver. No significant additional noise is added to the receiver by the photonic LO in the frequency range of 96–110 GHz.

Hitoshi Kiuchi, Masao Saito, Satoru Iguchi

In signal transmission through optical fiber, cable length delay fluctuation accompanied by chromatic and polarization-mode dispersion affects the coherence of distributed signals. To maintain signal coherence, it is very important to generate very-high-frequency signals with minimum phase noise and transmission loss. In a photonic local signal generation/distribution system with a microwave-photonic signal generator and a real-time microwave-photonic signal phase stabilizer that we developed as an alternative photonic LO system for ALMA (Atacama Large Millimeter/sub-millimeter Array), signals are transmitted in the form of frequency difference between two coherent light waves, effectively maintaining the coherence of distributed reference signals. Through the development of the real-time phase stabilizer, we discovered that the system would be further improved with the introduction of a post-processing scheme phase stabilizer and confirmed its effectiveness by experiments.

Yoshinori Uzawa, Akira Kawakami, Takafumi Kojima +6 more

A waveguide Josephson array oscillator operating at a frequency of 100 GHz was designed and fabricated to evaluate its pumping capability as a local oscillator (LO) for our proposed SIS mixer-based amplifier, which incorporates SIS up- and down-converters. The LO power requirement was estimated by simulation to be several nanowatts when the SIS up-converter is optimized for noise temperature and conversion gain under the condition that the input port at the microwave frequencies is connected to a practical 50-W system. The fabricated waveguide Josephson array oscillator module has 31 Nb Josephson junctions placed at the center of a half-wavelength resonator of an Nb microstripline. The output power from the waveguide oscillator module was evaluated by connecting it to the waveguide SIS detector module in a 4-K cryostat. Photon-assisted tunneling steps were clearly observed, from which the detected power was estimated to be approximately 17 nW at 106 GHz. These results suggest that the Josephson array oscillator is capable of being used in the SIS mixer-based amplifier as the LO.