New semiconductor maser operates continuously above room temperature
Lasers have become indispensable in everyday life and research, with applications ranging from data transmission and metrology to manufacturing. Masers, by contrast, have so far found hardly any practical applications.
A breakthrough in semiconductor technology has led to the development of a maser that operates continuously above room temperature. Masers, which stand for Microwave Amplification by Stimulated Emission of Radiation, work similarly to lasers but generate and amplify microwave radiation instead of light. Traditionally, masers have been limited by the need for extremely low temperatures to function, hindering their widespread use.
However, a team of researchers from Julius-Maximilians-Universität Würzburg (JMU) has made significant progress in creating a practical maser system.
The scientists developed a maser using silicon carbide, a semiconductor material that is already widely used in power electronics and readily available for industrial applications. By introducing atomic defects in the silicon carbide crystal lattice, the researchers created quantum spin states that can be selectively excited using light. When these spins are excited, they emit coherent microwave radiation or amplify it, turning the silicon carbide into a material that actively interacts with microwaves.
To achieve continuous operation at room temperature, the team engineered a high-quality microwave resonator, similar to how a swing builds up and amplifies oscillations at the right frequency. This improvement in the resonator's quality factor allowed the maser to function continuously at room temperature. The new silicon-carbide maser can be used not only as a microwave source but also as a low-noise amplifier, which is crucial for weak signals in communications and measurement technology.
Furthermore, the maser's exceptional frequency stability enables highly precise magnetic field measurements. Its sensitivity of around 20 picotesla at room temperature is about one million times weaker than Earth's magnetic field. This level of precision could be valuable for future metrology applications and even for GPS-independent navigation.
The researchers envision electrically driven maser diodes integrated on a chip, supported by the fact that silicon carbide spin states can be excited both optically and electrically.
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