Erina Nishida

Search for a stochastic background of 100-MHz gravitational waves with laser interferometers

This Letter reports the results of a search for a stochastic background of gravitational waves (GW) at 100 MHz by laser interferometry. We have developed a GW detector, which is a pair of 75-cm baseline synchronous recycling (resonant recycling) interferometers. Each interferometer has a strain sensitivity of approximately 10;{-16} Hz;{-1/2} at 100 MHz. By cross-correlating the outputs of the two interferometers within 1000 seconds, we found h{100};{2}Omega_{gw}<6 x 10;{25} to be an upper limit on the energy density spectrum of the GW background in a 2-kHz bandwidth around 100 MHz, where a flat spectrum is assumed.

Laser-interferometric Detectors for Gravitational Wave Backgrounds at 100 MHz : Detector Design and Sensitivity

Recently, observational searches for gravitational wave background (GWB) have been developed and given direct and indirect constraints on the energy density of GWB in a broad range of frequencies. These constraints have already rejected some theoretical models of large GWB spectra. However, at 100 MHz, there is no strict upper limit from direct observation, though the indirect limit by

Precise Measurement of Laser Power using an Optomechanical System

^{2}mathrm{He}

Optimal Location of Two Laser-interferometric Detectors for Gravitational Wave Backgrounds at 100-MHz

abundance due to big-bang nucleosynthesis exists. In this paper, we propose an experiment with laser interferometers searching GWB at 100 MHz. We considered three detector designs and evaluated the GW response functions of a single detector. As a result, we found that, at 100 MHz, the most sensitive detector is the design, a so-called synchronous recycling interferometer, which has better sensitivity than an ordinary Fabry-Perot Michelson interferometer by a factor of 3.3 at 100 MHz. When we select the arm length of 0.75 m and realistic optical parameters, the best sensitivity achievable is

High accuracy measurement of the quantum efficiency using radiation pressure

hensuremath{approx}7.8ifmmodetimeselsetexttimesfi{}{10}^{ensuremath{-}21}text{ }text{ }{mathrm{Hz}}^{ensuremath{-}1/2}

Development of a detector pair for very high frequency gravitational waves

at 100 MHz with bandwidth

O ptim alLocation ofTwo Laser-interferom etric D etectors for G ravitationalW ave B ackgrounds at 100 M Hz

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24aGJ-5 Interferometer Design of LCGT II

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30pSC-11 Measurement of quantum efficiency using radiation pressure

This paper shows a novel method to precisely measure the laser power using an optomechanical system. By measuring a mirror displacement caused by the reflection of an amplitude modulated laser beam, the number of photons in the incident continuous-wave laser can be precisely measured. We have demonstrated this principle by means of a prototype experiment uses a suspended 25 mg mirror as an mechanical oscillator coupled with the radiation pressure and a Michelson interferometer as the displacement sensor. A measurement of the laser power with an uncertainty of less than one percent (1σ) is achievable.

SearchforaStochasticBackgroundof100-MHzGravitationalWaveswithLaser Interferometers

Recently, observational searches for a gravitational wave background (GWB) have been developed and given constraints on the energy density of a GWB in a broad range of frequencies. These constraints have already resulted in the rejection of some theoretical models of relatively large GWB spectra. However, at 100 MHz, there is no strict upper limit from direct observation, though an indirect limit exists due to 4He abundance due to big-bang nucleosynthesis. In our previous paper, we investigated the detector designs that can effectively respond to GW at high frequencies, and found that the configuration, a so-called synchronous-recycling interferometer is best at these sensitivities. In this paper, we investigated the location and orientation dependence of two synchronous-recycling interferometers in detail, and derived the optimal location of the two detectors and the cross-correlation sensitivity to GWB. We found that the sensitivity is nearly optimized and hardly changed if two coaligned detectors are located in a range of ±0.2m.