Second-order interference of two independent photons with different spectra

The second-order interference of two independent photons with different spectra in a Shih-Alley/Hong-Ou-Mandel interferometer is studied in Feynman's path integral theory. There is a second-order interference pattern for photons with different spectra if the photons are indistinguishable for the employed detection system. The conditions to observe the second-order temporal beating with photons of different spectra are analyzed. The influence of the response time of the detection system on the observed second-order interference pattern is also discussed. It is a direct result of that measurement in quantum mechanics is dependent on the employed measuring apparatus. The results are helpful to understand the physics of two-photon interference in different schemes.

An all-optical time-delay relay based on a bacteriorhodopsin film

Using a special property of dynamic complementary-suppression-modulated transmission （DCSMT） in the bacteriorhodopsin （bR） film, we have demonstrated an all-optical time-delay relay. To extend our work, the relationship between the delay time of the all-optical time-delay relay and parameters of a bR film is numerically studied. We show how the delay time changes with the product of concentration and thickness （PCT） of a bR film. Furthermore, the shortest and longest delay times are given for the relay of ＇switch off. The saturable delay time and maximum delaytime of ＇switch on＇ are also given. How the wavelengths （632.8, 568, 533 and 412 nm） and intensities of the illuminating light influence the delay time is also discussed. The simulation results are useful for optimizing the design of all-optical time-delay relays.