This paper presents experimental studies on heterodyne Frequency Modulated Continuous Wave (FMCW) signal reception for different optical heterodyne configurations including internal and external mixing between an incoming signal and a local oscillator. Signals and potential noise sources from a fibered FMCW Mach-Zehnder Interferometer (FMCW MZI) are theoretically evaluated. These optical estimations (signal and noise) of various power spectral densities (PSD) are converted into electrical unities to be compared to the measurements.The PSD are validated by using a known alternating voltage with controlled frequency and amplitude. This validation is used to compare the experimental and theoretical detection limits of different FMCW photodetectors, including a Photonic Integrated Circuit (PIC) detector developed and produced at CEA. The detection limit achieved with this PIC module closely matches with the expected theoretical performances. It validates the optical and electronic architecture and the achievements of CEA’s design. The miniaturization of this operational detection module is underway. In the future, it will be located on a single chip alongside two Optical Phased Arrays (OPA), one for emission and the other for reception.
CEA aims at developing a compact 1550 nm Frequency Modulated Continuous Wave (FMCW) LiDAR on chip. In this paper, individual demonstrators, corresponding to three main components of a LiDAR (Light Distance And Ranging) system, are combined in a test bench: a FMCW laser source, an emission and reception Optical Phased Array (OPA) and an optical heterodyne detection module. Each component has been individually tested, but also evaluated in order to derive the system performance of a complete LiDAR. A test platform has been developed to calibrate an OPA fabricated at CEA platform, either in emission or in reception mode. The tested OPA includes 256 channels based on grating antennae, with 1.5 μm pitch and 256 thermo-optic phase shifters. More recently, this platform has been completed with a FMCW interferometer, where the FMCW LiDAR detection can be evaluated through a mixed propagation setup, composed of optical fibers and free space. Then, the OPA may be inserted into this setup. Therefore, the optical fiber FMCW interferometer has been optimized to detect the lowest signal (typically less than one hundred fW) and to estimate the signal-to-noise ratio (up to almost 30 dB) with low noise photodiodes. Performance has been compared to theoretical predictions. Then, our custom OPA is included inside this experimental setup in a free space propagation environment. The performance measurements extracted from the spectral analysis are in agreement with the expectations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.