Light sources and detectors

Light sources and optical detectors form the foundation of optical imaging techniques. The properties of light sources and optical detectors directly determines the performance of optical imaging. For instance, label-free nonlinear optical imaging, widely investigated in the past few decades, is stimulated by the recent advance of ultrafast pulsed lasers. For long, novel optical imaging techniques have been formulated based on off-the-shelf light sources and photon detectors. However, many fundamental limits of optical imaging, such as imaging depth, speed, and susceptibility to ambient light, cannot be overcome without the next-generation light sources and detectors.  

Since its establishment, BIL has been putting continuous efforts into the development of novel light sources and detection methods to circumvent the fundamental problems in optical imaging.

The integration of multiple nonlinear optical imaging modalities is difficult in that different imaging modalities require different excitation wavelengths, typically involving more than one laser source. In response to this, researchers in our lab developed a programmable supercontinuum laser source that offers the flexibilities of switching between different excitation wavelengths and pulse durations, enabling single-source multimodal nonlinear optical imaging.

 In addition, BIL also explores novel optical detection methods with improved sensitivity and robustness. In nonlinear optical imaging, photomultiplier tubes (PMTs) are the most popular options. However, PMTs suffer from the susceptibility to ambient light and low sensitivity at the infrared range. Our lab is working on an all-optical signal amplification and detection method based on optical parametric amplification that provides a lower detection limit than the PMTs and is immune to the interference of ambient light.

Our work on light sources and photodetectors has given birth to many advanced imaging techniques like SLAM and ambient-light-on nonlinear optical imaging, and we believe there are other potential imaging techniques enabled by our novel light sources and photodetectors.