Phase-noise model for actively linearized frequency-modulated continuous-wave ladar.

Understanding the effects of laser phase noise on frequency-modulated continuous-wave distance measurements is important in evaluating ranging accuracy. The standard white-frequency-noise assumption is commonly used to predict the ranging performance. However, other noise sources are typically present that can further degrade the heterodyne beat signal and make this assumption invalid.

Multi-terahertz frequency sweeps for high-resolution, frequency-modulated continuous wave ladar using a distributed feedback laser array.

Swept-wavelength reflectometry is an absolute distance measurement technique with significant sensitivity and detector bandwidth advantages over normal pulsed, time-of-flight methods. Although several tunable laser sources exist, many exhibit short coherence lengths or require mechanical tuning components. Semiconductor distributed feedback laser diodes (DFBs) are advantageous as a swept source because they exhibit a narrow instantaneous linewidth and can be frequency-swept simply via a single injection current.

Large-volume, low-cost, high-precision FMCW tomography using stitched DFBs.

Optical frequency-modulated continuous-wave (FMCW) reflectometry is a ranging technique that allows for high-resolution distance measurements over long ranges. Similarly, swept-source optical coherence tomography (SS-OCT) provides high-resolution depth imaging over typically shorter distances and higher scan speeds. In this work, we demonstrate a low-cost, low-bandwidth 3D imaging system that provides the high axial resolution imaging capability normally associated with SS-OCT over typical FMCW ranging depths.