Novel method for high resolution measurement of laser output spectrum

Okoshi, T.; Kikuchi, K.; Nakayama, A.

doi:10.1049/el:19800437

Cited by 889 publications

(290 citation statements)

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“…The linewidth was evaluated separately for each laser using the self-heterodyne technique [18] with a 5 km fibre delay line, the results of which are presented in Fig. 2 a) and b), respectively for the laser with and without a passive phase section.…”

Section: Monolithic Photonic Integrate Circuitmentioning

confidence: 99%

Optical injection locking of monolithically integrated photonic source for generation of high purity signals above 100 GHz

et al. 2014

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A monolithically integrated photonic source for tuneable mmwave signal generation has been fabricated. The source consists of 14 active components, i.e. semiconductor lasers, amplifiers and photodetectors, all integrated on a 3 mm 2 InP chip. Heterodyne signals in the range between 85 GHz and 120 GHz with up to -10 dBm output power have been successfully generated. By optically injection locking the integrated lasers to an external optical comb source, high-spectral-purity signals at frequencies >100 GHz have been generated, with phase noise spectral density below -90 dBc/Hz being achieved at offsets from the carrier greater than 10 kHz.

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Section: Monolithic Photonic Integrate Circuitmentioning

confidence: 99%

Optical injection locking of monolithically integrated photonic source for generation of high purity signals above 100 GHz

et al. 2014

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“…While the heterodyne measurement is sensitive to the time-averaged absolute line width, the instantaneous modulation of a high frequency signal is best detected by demodulation using a homodyne technique [117]. We have measured the homodyne emission spectrum of the 250 GHz gyrotron using a diode detector and an oscilloscope (LeCroy, Model LT354) capable of sampling for several tens of seconds of acquisition.…”

Section: Spectral Puritymentioning

confidence: 99%

250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

Bajaj

Hornstein

Kreischer

et al. 2007

Journal of Magnetic Resonance

162

130

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In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9T, corresponding to 380 MHz 1 H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP-enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP-enhanced multidimensional NMR. These results include assignment of active site resonances in [U-13 C, 15 N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperaturedependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as low 12 mA) at frequencies between 320-365 GHz, suggesting an efficient route for the generation of even higher frequency radiation. The low starting currents were attributed to an elevated cavity Q, which is confirmed by cavity thermal load measurements. We conclude with an appendix containing a detailed description of the control system that safely automates all aspects of the gyrotron operation.

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“…set up a narrow-band laser excitation system with linewidth below the Doppler limit, which enables us to test for much longer coherence times. To determine the linewidth of our combined laser system, we employ a delayed self-heterodyne interferometer 12 using a 10-km-long fibre as delay line. For both excitation lasers we independently obtain linewidths of less than 20 kHz.…”

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confidence: 99%

Atom–molecule coherence for ultralong-range Rydberg dimers

et al. 2010

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An important goal in quantum chemistry is the coherent control of reversible reactions between pure initial and final states of individual constituents. Recent examples of coherent control of such chemical reactions include the photoassociation of ultracold ground-state dimer molecules 1,2 and of Feshbach molecules in highly excited vibrational states 3 . Here, we extend coherent control of such reactions to the photoassociation of dimer states in highly excited electronic states. We demonstrate coherent transfer of initially free pairs of rubidium ground-state atoms to ultralong-range Rydberg molecules consisting of a highly excited Rydberg atom and a ground-state atom 4,5 . The coherent evolution of the molecular system is monitored in echo and Ramsey-pulse sequences by measuring the timescales for the energy-conserving dephasing rate, T 2 , and for non-energy-conserving decay processes, T 1 . These experiments demonstrate an atom-molecule interferometer with Rydberg states.Ultralong-range Rydberg molecules are based on an exotic binding mechanism based on attractive electron-atom scattering. Since their first experimental observation 5 , spectroscopic studies of these unusual molecular states have unveiled another new binding mechanism for ultralong-range Rydberg molecules based on quantum reflection 6 . However, the investigation of the dynamical properties of the ultralong-range Rydberg molecules demands experimental methods going beyond continuous-wave spectroscopy.In the following we demonstrate that our narrow-band laser set-up can coherently drive a system consisting of two rubidium ground-state atoms between the unbound 5s-5s pair state and the bound 3 (5s-35s) molecular ground state by means of a rotary echo-type technique. We model the experimental results with a two-level optical Bloch calculation. The found dephasing and decoherence properties of the system are convincingly reproduced in a Ramsey-type experiment, that is set up to realize an atommolecule interferometer.We create the ultralong-range Rydberg molecules in the 3 (5s-35s)(ν = 0) vibrational ground state from a sample of approximately 2 × 10 6 87 Rb atoms at a temperature of 3 µK in the ground state 5s 1/2 (F = 2; m F = 2) by means of a twophoton transition. The two lasers at 780 nm and 480 nm are detuned by ≈400 MHz from the intermediate 5p 3/2 state (see Methods). A schematic diagram of the levels and the excitation lasers is given in Fig. 1a.Recently, Rabi oscillations of single Rydberg atoms were observed over several microseconds 7,8 . In contrast, previous coherence measurements in many-body ultracold Rydberg systems did not allow observation of coherence times of more than a few hundred nanoseconds owing to laser linewidths of ∼ > 1 MHz (refs 9-11). However, for an atomic sample at a temperature of 3 µK, we expect a Doppler broadening of only 125 kHz full-width at half-maximum as the dominant line-broadening mechanism. Therefore, we have 5. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, German...

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Novel method for high resolution measurement of laser output spectrum

Cited by 889 publications

References 1 publication

Optical injection locking of monolithically integrated photonic source for generation of high purity signals above 100 GHz

Optical injection locking of monolithically integrated photonic source for generation of high purity signals above 100 GHz

250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

Atom–molecule coherence for ultralong-range Rydberg dimers

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