Showing papers by "James C. Bergquist published in 1983"
TL;DR: Using pointcontact metal insulator-metal diodes, this paper demonstrated heterodyne detection of visible laser radiation at frequency differences up to 2.5 THz (generated by a 119μm laser) and showed that the signal to noise on the observed rf beat falls off at 2.3 dB/octave of laser frequency difference.
Abstract: Using point‐contact metal‐insulator‐metal diodes, we have demonstrated heterodyne detection of visible laser radiation at frequency differences up to 2.5 THz (generated by a 119‐μm laser). The signal to noise on the observed rf beat falls off at 2.3 dB/octave of laser frequency difference and would seem to indicate that 30‐THz difference beats will be obervable with improved laser stability or signal averaging. While the diode detector ‘‘bandwidth’’ per se has not been evaluated, these measurements demonstrate an increase in the frequency difference which can be measured in the visible by more than an order of magnitude over that previously reported.
57 citations
TL;DR: Several microwatts of tunable cw radiation near 194 nm in a linewidth of less than 2 MHz have been generated by sum-frequency mixing the radiation from a frequency-doubled argon-ion laser with the Radiation from a ring dye laser in a crystal of potassium pentaborate.
Abstract: Several microwatts of tunable cw radiation near 194 nm in a linewidth of less than 2 MHz have been generated by sum-frequency mixing the radiation from a frequency-doubled argon-ion laser with the radiation from a ring dye laser in a crystal of potassium pentaborate. An external ring cavity resonant with the dye laser gives an enhancement factor of about 14 in the sum-frequency-generated radiation power. The Doppler-limited absorption spectrum of the 6s2S1/2–6p2P1/2 first resonance line of natural Hg ii has been resolved, and the vacuum wave number for the mass-202 isotope has been measured to be 51485.904(20) cm−1.
54 citations
TL;DR: In this paper, an external ring cavity, resonant with the ring dye laser, gives a power enhancement of about 12 in the sum-frequency generated radiation with a linewidth of less than 4 MHz.
6 citations
TL;DR: In this article, a frequency standard for microwave hyperfine transitions of atomic ions stored in Penning-type ion traps has been proposed, based on internal resonance transitions of ions confined in electromagnetic traps.
Abstract: Microwave or optical frequency standards based on internal resonance transitions of ions confined in electromagnetic traps have the fundamental advantages of long observation times and small perturbations. These advantages are somewhat offset by low signal to noise ratios. Work at NBS has concentrated on microwave hyperfine transitions of atomic ions stored in Penning-type ion traps. The use of narrowband, tunable light sources for state selection and detection and for reducing the average kinetic energy of the ions (laser cooling) is an important feature of this work. Results to date include the fluorescence detection and cooling to about 50 mK of a single Mg+ ion and the observation of a 0.012 Hz linewidth on a 300 MHz 25Mg+ hyperfine transition. A frequency standard based on 201Hg+ ions is under development. Related work, mostly based on RF-type ion traps, is underway at several other labs.
1 citations