We have developed a balanced homodyne detector capable of working with femtosecond pulsed light at a 76MHz repetition rate and 800nm wavelength. It exhibits a common mode rejection ratio of 55dB, and can achieve the shot-noise limit. Provided with good performance, our detector can be used in high speed quantum information applications.
We present a high-speed time-domain shot-noise-limited balanced homodyne detector that is suitable for the detection of the quantum states of nanosecond pulsed optical fields. The detector can detect the quantum noise of individual nanosecond optical pulses at a repetition rate of 40 MHz and achieve a signal-to-noise ratio of above 14.5 dB at a local oscillator power of 9.9×107 photons per pulse. The stability of the detector is characterized via an Allan variance measurement, and superior stability is observed. The detector is especially applicable in the fields of quantum optics and quantum information, where high-speed time-domain detection of nanosecond pulsed optical field quadratures is required.
We design and experimentally characterize a balanced homodyne detector optimized for high-repetition-rate (100 MHz) pulsed optical sources. Unlike conventional transimpedance-amplifier architectures, which suffer from nonlinearities and dynamic instabilities with ultrashort pulses, our approach allows to directly amplify the photocurrent extracted at the common photodiode node without feedback loops. A theoretical model describing the detector response, noise, and pulse-to-pulse correlations is developed, providing quantitative predictions for the signal variance, signal-to-noise ratio (SNR), and inter-pulse correlations. Implemented with two matched InGaAs photodiodes illuminated by a 1030 nm mode-locked laser at 100 MHz, the detector exhibits excellent linearity and shot-noise-limited scaling of the signal variance with optical power. Optimizing the temporal integration window yields a maximum SNR of about 14 dB, while correlation measurements confirm negligible inter-pulse correlations. These results demonstrate that the proposed architecture offers a robust and simple solution for high-speed pulsed homodyne detection, suitable for quantum optics and continuous-variable quantum information applications.
A balanced homodyne detection scheme with nanosecond time resolution and sub-shot-noise sensitivity has been developed and successfully tested yielding an efficient detection scheme for high-speed quantum-optical measurements and communication protocols, for example, quantum cryptography. The parameters of the detector and its precise balancing allow complete characterization of quantum states created by femtosecond light pulses that include the measurement of photon number, optical phase, and statistical properties with a high signal-to-noise ratio for the whole bandwidth from DC to several tens of megahertz. The electronic part of the detector is based on a commercially available amplifier that provides ease of construction and use while yielding good performance.
This thesis reports the realization and applications of a versatile wideband balanced homodyne detector operating in the time domain and intended for Quantum Optical Tomography. The detector can work with high repetition rate lasers used for the production and measurement of the electric field quadratures of quantum states of light. Full characterization of the detector by shot-noise measurements and by verifying its capability to reconstruct the density matrix and Wigner function of various states of interest is given. By overcoming photodiodes response mismatch, high frequency electronics issues and by choosing an appropriate optical set-up, a high level of common mode suppression (52.4dB) and a low electronic noise gave a shot-to-electronic noise ratio of I3dB for a Local Oscillator with 6.2 x 108 photons-per-pulse on a ~ 100MHz bandwidth. Results for the characterization of a single-photon Fock state are presented. An average efficiency of 56% was obtained for the generation/detection of the state.
The research of quantum noise in the interaction of laser and atoms plays a critical role in quantum optical experiments. The measurement of quantum noise is mainly based on the balanced homodyne detection method. Here, we reported a balanced homodyne detector with low noise, high gain, and high common-mode rejection ratio (CMRR) at the wavelength of 795 nm. By optimizing the selection of components and printed circuit board (PCB) layout, a minimum electronic noise of −96.7 dBm is obtained. Over the range of 1 MHz to 5 MHz, we get a flat CMRR above 59 dB and a linear gain regime, which can enable a shot noise measurement with the laser power of100μw. The developed detector can be used in quantum coherent experiments with a weak probe laser of power down to tens of microwatts.