An Integrated Millimeter-Wave Satellite Radiometer Working at Room-Temperature with High Photon Conversion Efficiency

Area of Science:

• Photonics and Optics
• Microwave Engineering
• Remote Sensing

Background:

• Conventional Low Noise Amplifiers (LNAs) and Schottky mixers face limitations in sensitivity and operating temperature for advanced earth observation.
• The need for compact, efficient, and room-temperature receiver frontends is critical for next-generation satellite missions.

Purpose of the Study:

• To present the design of an integrated 183GHz radiometer frontend for satellite-based earth observation.
• To propose a novel receiver frontend utilizing electro-optic modulation as an alternative to traditional LNAs and Schottky mixers.
• To achieve efficient millimeter-wave to optical signal conversion at room temperature.

Main Methods:

• Utilizing efficient electro-optic modulation of a laser pump with the millimeter-wave signal.
• Employing a triply resonant high-Q Lithium Niobate (LN) Whispering Gallery Mode (WGM) resonator for nonlinear optical upconversion.
• Engineering a micromachined millimeter-wave cavity for maximized optical mode overlap and phase matching.

Main Results:

• Achieved efficient millimeter-wave to 1550 nm optical upconversion via nonlinear optical processes.
• Demonstrated a predicted normalized photon-conversion efficiency of approximately 10^-1 per mW pump power.
• Exceeded the state-of-the-art by three orders of magnitude at millimeter-wave frequencies.

Conclusions:

• The proposed electro-optic modulation approach offers a promising room-temperature, low-noise receiver frontend alternative.
• The integrated design with a micromachined cavity and LN WGM resonator significantly enhances conversion efficiency.
• A piezo-driven tuning mechanism simplifies manufacturing and compensates for tolerances, paving the way for practical implementation.