Humio INABA

Department of Electronics, Tohoku Institute of Technology, 35-1 Yagiyama-Kasumicho, Taihaku-ku, Sendai, 982 Japan, and Biophotonics Information Laboratories, 2-2-1, Matsuei, Yamagata, 990 Japan

(Received June 27, 1996; Accepted September 12, 1996)

In advanced sensing photonics it is of great importance to explore the detection limits of extremely weak optical signals and imaging using state-of-the art technology. In this paper we describe recent progress in photonic sensing technology achieved in practice in the standard quantum limit of optical detection imposed by the signal-limited shot noise, which can be realized by both the optical heterodyne detection and photon counting techniques. Then, with particular attention on imaging of ultraweak photonic signals by these techniques, their applications in developing new frontiers in the field of biophotonics such as laser computed tomography, and the imaging and characterization of ultraweak biophoton emission phenomena are described and discussed as one of the typical examples of future trends in this field.

Key words : photonic sensing technology, advanced sensing photonics, standard quantum detection limit, optical heterodyne detection method, photon counting method, laser computed tomography, ultraweak biophoton emission, nonclassical light, squeezed states, photon number states