Investigation of an optical amplification t echnique t o improve sensitivity of an optical property modulation-based radiation detection method for PET

The optical amplification effect achieved by adopting high quality factor (high-Q) optical resonant cavities has shown the ability to enable ultra-high sensitivity measurement for refractive index modulation. In this work, we investigate the usage of optical amplification effect for improving the detection sensitivity for optical modulation-based radiation detection method for positron emission tomography (PET), with the ultimate goal to achieve individual annihilation photon detection with significantly improved coincidence time resolution (CTR). We studied the detection sensitivity of etalon cavities made of 50%, 90% and 95% reflection cavity mirrors, and compared the sensitivity to our previous spatial interference setup. We also studied the influence of optical concentration on the detection sensitivity by using a focused probe laser beam aligned to intercept the interaction region of ionizing radiation photons with the detector crystal. A detection sensitivity boost of approximately two orders of magnitude has been observed using etalon cavity made of 95% reflection mirrors with 1mm diameter focused probe laser beam, compared to our previous spatial interference setup. The detection speed is not affected by using high-Q cavities. This proves the potential of using the optical amplification effect to dramatically improve the detection sensitivity for optical modulation-based radiation detection method for PET, with the ultimate goal to achieve individual 511keV photon detection with ultrafast CTR.