Hidetsuka Imajo

Continuous-wave sum-frequency generation near 194 nm in β-BaB 2 O 4 crystals with an enhancement cavity

Continuous-wave coherent radiation tunable near 194 nm has been generated by sum-frequency generation in beta-BaB(2)O(4) placed inside an external enhancement cavity. An output power of 16 microW has been obtained with a walk-off-compensated configuration of beta-BaB(2)O(4) crystals.

High-power second-harmonic generation with picosecond and hundreds-of-picosecond pulses of a cw mode-locked Ti:sapphire laser.

A cw mode-locked Ti:sapphire laser was efficiently frequency doubled with a lithium triborate crystal in an external enhancement cavity. Second-harmonic output powers of 1.28 W and 860 mW have been generated at 399 nm with fundamental pulse widths of 1.5 and 320 ps, respectively. At the 1.5-ps pulse width the conversion efficiency was 75%. The spectral width of the 320-ps pulses, produced by modification of a laser cavity, is as narrow as the bandwidth of a normal cw, multimode, narrow-bandwidth Ti:sapphire laser. The frequency-doubled output can be thus used as a high-power, narrow-bandwidth light source in the UV region.

Laser cooling of trapped Ca(+) and measurement of the 3(2)D(5/2) state lifetime.

We describe the laser cooling of Ca(+) ions in a rf ion trap and the measurement of its 3(2)D(5/2) state lifetime. The ions are cooled to below 1 K by radiation from a frequency-doubled Ti:sapphire laser and a laser diode. The radiative lifetime is measured by observing the change in fluorescence when the ions, which are optically pumped to the metastable state, return to the cooling cycle. The lifetime of the 3(2)D(5/2) state is measured to be 0.77 +/- 0.07 s.

Velocity control of an Yb beam by a frequency-doubled mode-locked laser

An ytterbium atomic beam has been decelerated with the use of a multimode light beam based on a frequency-doubled mode-locked Ti:sapphire laser. Compression of the atomic velocity distribution was achieved by the addition of a copropagating single-mode light beam. The contribution of each isotope to the observed compressed peaks of the velocity distribution is explained.

Measurements of Motional Frequencies for Laser-cooled Ions in a Penning Trap

Abstract The characteristics of laser-cooled Be+ ions stored in a Penning trap are reported. Be+ ions are cooled by a laser to approximately 300 mK and the cyclotron and axial frequencies of the cooled ions are measured by a laser fluorescence technique. In addition, ion resonances are observed when several kinds of ions are trapped with Be+ ions.

Laser cooling and isotope separation of Cd + ions confined in a linear Paul trap

Cadmium ions in a natural isotope mixture have been trapped in a linear Paul trap and laser cooled. The fluorescence spectra from all even isotopes, including the (108)Cd(+) isotopes with a natural abundance of 0.89%, were observed. Additionally, we eliminated the heavier isotopes from the trapping region by adjusting the tuning of the laser frequency and by changing the dc voltage applied to the end electrodes.

Sum-Frequency Generation near 194 nm with an External Cavity by Simultaneous Enhancement of Frequency-Stabilized Fundamental Lasers

Continuous-wave coherent radiation near 194 nm has been generated by sum-frequency mixing with simultaneous enhancement of both fundamental lasers. An output power of 31 µ W was obtained at 194 nm. The frequency of a Ti: sapphire laser, which was used as one of the fundamental lasers, was stabilized with a frequency fluctuation of 80 kHz rms by using a mode-interference method.

Tunable 397 nm Light Source for Laser Cooling of Ca Ions Based on Frequency Doubling of Diode Laser

We have fabricated an rf ion trap and laser-cooling light sources to observe shelving transition in a single calcium ion. All the radiation required for laser cooling and observation of the transition can be prepared with diode lasers in this system. Continuous-wave radiation at 397 nm for laser cooling was generated by frequency doubling of a GaAlAs laser in an external enhancement cavity. As a preliminary experiment for observing the shelving transition, laser cooling of one hundred calcium ions was demonstrated using this radiation and another diode laser.

Optical Detection of Stored Ca

Abstract This paper describes the results of optical detection of Ca+ ions stored in an rf ion trap by using a frequency-doubled Ti: sapphire laser and a laser diode. Some experimental results of the characteristics of the stored ions are shown.

Laser Cooling of Ca^+ Ions and Observation of Collision Effects

This paper describes our recent experimental results on trapping and laser cooling of Ca + ions. The measurement of the characteristics of laser-cooled Ca + ions in an rf quadrupole ion trap, such as the fluorescence line shape and phase transition, is described. Observation of two types of collision-induced «quantum jumps» of a Ca + ion in a background gas of H 2 or air is also described. Since the rate of the collision-induced jumps is very high for Ca + , it is necessary to achieve an extremely high vacuum condition for frequency standard applications