To benefit high-power interferometry and the creation of low-noise light sources, we develop a simple lead-compensated photodetector enabling quantum-limited readout from 0.3 mW to 10 mW and 10 k$Ω$ transimpedance gain from 85 Hz - 35 MHz. Feeding the detector output back to an intensity modulator, we squash the classical amplitude noise of a commercial 1550 nm fiber laser to the shot noise limit over a bandwidth of 700 Hz - 200 kHz, observing no degradation to its (nominally ~100 Hz) linewidth.
We propose a method to track signals from quadrant photodiodes (QPD) in heterodyne laser interferometers that employ digital phase-locked loops for phase readout. Instead of separately tracking the four segments from the QPD and then combining the results into length and Differential Wavefront Sensing (DWS) signals, this method employs a set of coupled tracking loops that operate directly on the combined length and angular signals. Benefits are increased signal-to-noise ratio in the loops and the possibility to adapt the loop bandwidths to the different dynamical behavior of the signals being …
Single photon detectors have dark count rates that depend strongly on the bias level for detector operation. In the case of weak light sources such as novel lasers or single-photon emitters, the rate of counts due to the light source can be comparable to that of the detector dark counts. In such cases, a characterization of the statistical properties of the dark counts is necessary. The dark counts are often assumed to follow a Poisson process that is statistically independent of the incident photon counts. This assumption must be validated for specific types of photodetectors. In this work, w…
Millimeter-wave (mmWave) technology continues to draw large interest due to its broad applications in wireless communications, radar, and spectroscopy. Compared to pure electronic solutions, photonic-based mmWave generation provides wide bandwidth, low power dissipation, and remoting through low-loss fiber. However, at high frequencies, two major challenges exist for the photonic system: the power roll-off of the photodiode, and the large signal linewidth derived directly from the lasers. Here, we demonstrate a new photonic mmWave platform by combining integrated microresonator solitons and hi…
Ultra-low phase-noise microwave generation using a diode-pumped solid-state laser based frequency comb and a polarization-maintaining pulse interleaver
All gravitational-wave observatories (GWOs) have been using the laser wavelength of 1064 nm. Ultra-stable laser devices are at the sites of GEO 600, Kagra, LIGO and Virgo. Since 2019, not only GEO 600 but also LIGO and Virgo have been using separate devices for squeezing the uncertainty of the light, so-called squeeze lasers. The sensitivities of future GWOs will strongly gain from reducing the thermal noise of the suspended mirrors, which involves shifting the wavelength into the 2 $μ$m region. Our work aims for reusing the existing high-performance lasers at 1064 nm. Here, we report the real…
The cross-correlation sensitivity of two identical balanced photodiode heterodyne receivers is characterized. Both balanced photodiodes receive the same weak signal split up equally, a situation equivalent to an astronomical spatial interferometer. A common local oscillator (LO) is also split up equally and its phase difference between both receivers is stabilized. We show by semi-classical photon deletion theory that the post-detection laser shot noise contributions on both receivers must be completely uncorrelated in this case of passing three power splitters. We measured the auto- and cross…
A Simple and Robust Balanced Homodyne Detector for High-Repetition-Rate Pulsed Sources
Università degli Studi di Milano（米兰大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Milano（意大利国家核物理研究所，米兰分部）；Istituto di Fotonica e Nanotecnologie - CNR（光子学与纳米技术研究所-国家研究委员会）
Spectral purity of any millimeter wave (mmW) source is of the utmost interest in low-noise applications. Optical synthesis via photomixing is an attractive source for such mmWs, which usually involves expensive spectrally pure lasers with narrow linewidths approaching monochromaticity due to their inherent fabrication costs or specifications. Here, we report an alternative option for enhancing the spectral purity of inexpensive semiconductor diode lasers via a self-injection locking technique through corresponding Stokes waves from a fiber Brillouin cavity exhibiting greatly improved phase noi…
Beyond 350 GHz: Single-channel 112 Gbps photonic wireless transmission at 560 GHz using soliton microcombs
Institute of Post-LED Photonics (pLED), Tokushima University（德岛大学后发光二极管光子学研究所）；Graduate School of Sciences and Technology for Innovation, Tokushima University（德岛大学创新科学技术研究生院）；Tokushima Prefectural Industrial Technology Center（德岛县产业技术中心）；Center for Higher Education and Digital Transformation, University of Yamanashi（山梨大学高等教育与数字化转型中心）；National Institute of Information and Communications Technology（信息通信研究机构）；Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology（名古屋工业大学电气机械工程系）；Department of Electrical, Electronic and Computer Engineering, Gifu University（岐阜大学电气电子计算机工程系）；Institute of Photonics and Human Health Frontier (IPHF), Tokushima University（德岛大学光子学与人类健康前沿研究所）；Institute for Photon Science and Technology, The University of Tokyo（东京大学光子科学与技术研究所）
