We propose using a novel multifunction optical filter with a Michelson-Gires-Tournois interferometer (MGTI) for future smart wavelength-division-multiplexed network system applications. The MGTI filter is a typical Michelson interferometer in which one of its reflecting mirrors is replaced with a Gires-Tournois resonator. One unique feature of this device is that it can function as a channel-passing (CP), a channel-dropping (CD), or a wide-bandpass (BP) filter, depending on the interferometer arm-length difference. Other interesting features are that (1) the linewidths of both the CP and the CD filter are twice as narrow as that of a typical Fabry-Perot filter with similar parameters, (2) theoretical visibility is always unity regardless of the mirror reflectance value, and (3) the BP filter has an excellent boxlike response function. Numerical results showing these characteristics are presented.

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Besides its desirable power level, the use of a laser as a light source in microscopes opens the possibility of observing high signal-to-noise ratio images of dynamic phenomena that are sensitive to certain polarizations, excitation wavelengths, and phase shifts. However, the image quality is degraded by speckle noise. We propose a new fiber-illuminated laser-diode microscope that generates speckle-free images. The feedback effect in the laser diode is employed to transform a single-mode free-running laser into a multimode laser and to generate an output light whose multimode spectrum changes with time. The output of the laser diode is then passed through a multimode fiber whose exit face illuminates a conventional microscope with a continuously changing speckle pattern. These uncorrelated speckle patterns are averaged by a video detector to reduce speckle noise. The technique eliminates speckle noise without employing any moving mechanical parts and requires no additional electronics or extra optical elemen ts except one mirror and one beam splitter. An experimental result showing excellent reduction of speckle is presented.

We propose, simulate, and experimentally demonstrate a circuit analogue of a special relativity phenomenon known as relativistic aberration of light (RAL) by using a surprisingly simple, low-cost, and easily accessible electronic circuit-based all-pass filter. This work is useful for two audiences: (i) physicists who are interested in research on circuit analogues; and (ii) physics educators who are interested in using the research results to raise interest among students by incorporating analogue-based learning into undergraduate physics lecture and laboratory courses. For the first type of audience, we present a rigorous theoretical framework describing this RAL-on-an-electronic-chip analogy. We show by (i) analytical modelling, (ii) commercial circuit software simulation, and (iii) experiment that the electrical phase shift Φ of the output signal is analogous to the RAL angle, Ψ. This parameter opens up a path among researchers to model the effects of other relativistic phenomena with electronic circuits. For the second type of audience, we discuss the potential role of RAL-on-an-electronic-chip in physics education (both in lectures and laboratory) that combines students’ learnings of both physics and electronic circuits, at the same time. We also explore briefly its relevance to engineering education.

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