A solid-state cw optically pumped microwave maser. Exploring new active materials for low-noise room-temperature microwave amplifiers and other devices. Ultra-high frequency ultra-low dc power consumption HEMT amplifier for quantum measurements in millikelvin temperature range. SQUID-based microwave cavity search for dark-matter axions. A new look at the Saturn system: the Voyager 2 images. Cryogenic wide-band ultra-low-noise IF amplifiers operating at ultra-low DC power. On the intersystem crossing of pentacene in p-terphenyl. Electron spin echoes of a photoexcited triplet: pentacene in p-terphenyl crystals. EPR of photo-excited triplet states: a personal account. Theoretical and experimental sensitivities of ESR spectrometers using maser techniques. Maser oscillation in a whispering-gallery-mode microwave resonator. Ultra-stable performance of the superconducting cavity maser. ) (Deep Space Communication and Navigation Series, Jet Propulsion Laboratory, Caltech, 2008)ĭick, G. In Low-Noise Systems in the Deep Space Network (ed. Microwave Solid-State Masers (McGraw-Hill, 1964)Ĭlauss, R. Experimental study of coaxial free-electron maser based on two-dimensional distributed feedback. By exploiting the high levels of spin polarization readily generated by intersystem crossing in photo-excited pentacene and other aromatic molecules, this new type of maser seems to be capable of amplifying with a residual noise temperature far below room temperature. When configured as an oscillator, the solid-state maser’s measured output power of around −10 decibel milliwatts is approximately 100 million times greater than that of an atomic hydrogen maser 3, which oscillates at a similar frequency (about 1.42 gigahertz). The maser’s pumping mechanism exploits spin-selective molecular intersystem crossing 10 into pentacene’s triplet ground state 11, 12. In contrast to the cryogenic ruby maser 6, in our maser the gain medium is an organic mixed molecular crystal, p-terphenyl doped with pentacene, the latter being photo-excited by yellow light. It works on a laboratory bench, in air, in the terrestrial magnetic field and amplifies at around 1.45 gigahertz. Here we report the experimental demonstration of a solid-state maser operating at room temperature in pulsed mode. Overcoming these various obstacles would pave the way for improvements such as more-sensitive chemical assays, more-precise determinations of biomolecular structure and function, and more-accurate medical diagnostics (including tomography) based on enhanced magnetic resonance spectrometers 9 incorporating maser amplifiers and oscillators. Most realizations of masers also require strong magnets, magnetic shielding or both.

The maser’s relative obscurity has mainly been due to the inconvenience of the operating conditions needed for its various realizations: atomic 3 and free-electron 4 masers require vacuum chambers and pumping and solid-state masers 5, although they excel as low-noise amplifiers 6 and are occasionally incorporated in ultrastable oscillators 7, 8, typically require cryogenic refrigeration. However, the maser, which amplifies microwave radiation rather than visible light, has not had as large an impact, despite being instrumental in the laser’s birth 1, 2. The invention of the laser has resulted in many innovations, and the device has become ubiquitous.

Maser elyoum