J.R.M. Barr

A MEASUREMENT OF THE 1S-2S TRANSITION FREQUENCY IN MUONIUM

Doppler-free two-photon laser spectroscopy has been employed to measure the 12S12−22S12 transition in the muonium atom (μ+e−). A value of 2 455 529 002(33) (46) MHz has been obtained, which agrees with QED calculations within two standard deviations. The Lamb shift contributions are tested to the level 8×10−3. The corresponding measurements in hydrogen and deuterium using the same apparatus and laser system provide a test of the applied systematic corrections and have verified the systematic error of 46 MHz quoted. The mass of the positive muon has been derived from the isotope shift in this transition and yields a value of 105.65880(29)(43) MeVc2.

Mode locking of a diode-laser-pumped Nd:glass laser by frequency modulation

We report frequency-modulation mode locking of a diode-laser-pumped Nd:glass laser. We have obtained pulses of 9-psec duration using a lithium niobate phase modulator operating at a repetition rate of 235 MHz. The average output power is 14 mW, for pumping with a 500-mW laser-diode array, and the pulses are approximately 1.4 times transform limited.

Accurate optical frequency-interval measurement by use of nonresonant frequency comb generation

A novel technique for measuring the separation of widely spaced optical frequencies is demonstrated. It relies on frequency comb generation by use of a laser that incorporates a frequency-shifting element. A Nd:YLF laser is used to produce a frequency comb that has a bandwidth of 140 GHz and that contains in excess of 875 discrete frequencies, accurately spaced by 160 MHz. The longitudinal mode spacing of a dual-frequency laser was measured to an accuracy of +/-5 kHz in 3,733,440.0 kHz by use of the technique described here.

Frequency comb generation and pulsed operation in a Nd: YLF laser with frequency-shifted feedback

Abstract An injection-seeded Nd: YLF laser incorporating frequency shifted feedback generates a frequency comb with a 140 GHz bandwodth and a tunable frequency spacing. Near bandwidth-limited pulses of 31 ps duration have been produced in the seeded laser by matching the frequency shift to a multiple of the cavity roundtrip frequency.

Intracavity second harmonic generation of 0.532 μm in bulk periodically poled lithium niobate

Abstract We report on CW quasi-phase-matched intracavity frequency doubling of a 1.064 μm Nd:YAG laser. The 5 mm long and 0.2 mm thick crystal of periodically poled LiNbO3 was Brewster angle cut. When located intracavity, it presented an effective nonlinear coefficient d33 of 4.5 pm/V and an estimated loss per pass less than 10%. The observed temperature bandwidth of ∼ 5 K compares favourably with the theoretical value and indicates that the whole length of the crystal was contributing to the frequency doubling process.

Frequency shifted feedback and frequency comb generation in an Er3+ -doped fibre laser

The temporal and spectral characteristics are reported of an Er3+ -doped fibre laser incorporating frequency shifted feedback. The output of the free running laser was found to be either continuous-wave or train of driven relaxation oscillations depending on cavity loss. The performance is described and a simple theoretical model is used to predict the main features. Under cavity matching conditions, a train of pulses was generated with a repetition rate equal to the roundtrip time. Injection seeding of the laser generated a discrete comb of optical frequencies for applications in optical metrology.

A laser-diode-pumped Nd:Glass laser: mode-locked, high power, and single frequency performance

The authors report the performance of a laser-diode-pumped Nd:glass laser. Using the AM active mode-locking technique, pulses as short as 9 ps were obtained. The development of a high-power (415 mW), high-optical-slope-efficiency (32.4%) laser-diode-pumped Nd:glass laser using high-power, broad stripe laser diodes as the pump source is described. Single-frequency operation of the Nd:glass laser using an acoustooptic modulator to ensure unidirectional operation in a ring laser configuration was investigated. An instantaneous linewidth of less than 300 Hz was observed. >

Two-photon laser spectroscopy of the muonium 1S–2S transition

The 12S1/2(F=1)−22S1/2(F=1) energy interval in muonium has been investigated by Doppler-free two-photon laser spectroscopy. The transition was observed by uniquely identifying and counting the muons released after the photoionization of the 2S state by the same laser field. The measured transition frequency of 2455 528016(58)(43) MHz is in good agreement with QED calculations. The experiment can be interpreted as a test of the Lamb shift contributions at the 1% level. The method is also well suited for a precise determination of the mass of the positive muon in a muoniumhydrogen isotope shift measurement.

Self-starting additive-pulse mode locking of a Nd:LMA laser.

A Ti:sapphire-pumped Nd:LMA laser has been passively mode locked by using additive-pulse mode locking, which generates 600-fs-duration pulses at 1.054-µm. The wavelength, pulse duration, and long-term stability of the laser make it eminently suitable as a front-end oscillator of a high-power, chirped-pulse amplifier experiment based on 1.053-µm amplification in Nd:phosphate glass.

A high power, high efficiency, laser diode-pumped, continuous wave miniature Nd glass laser

Abstract We report the operation of a Nd:glass laser pumped by a 500 mW broad single stripe laser diode. We have observed a slope efficiency of greater than 30% and an output power of greater than 100 mW when pumping with one diode. The output power increased to greater than 150 mW when two such diodes were used to pump the laser.