A new wavelength-selective optical modulator was proposed and discussed. The modulator consists of three kinds of distributed Bragg reflectors (DBRs) integrated in a single straight waveguide. The waveguide can guide TE$_0$ and TE$_1$ modes, and an in-line Michelson interferometer is constructed by the three DBRs. An operation-wavelength wave among incident wavelength-division-multiplexed TE$_1$ guided waves is split into TE$_0$ and TE$_1$ guided waves by one of DBRs, and combined by the same DBR to be TE$_0$ output wave with interference after one of waves is phase-modulated. A modulator using an electro-optic (EO) polymer is designed, and the static performance was predicted theoretically. An operation principle was confirmed experimentally by a prototype device utilizing a thermo-optic effect instead of the EO effect.

The vertical-cavity surface-emitting laser (VCSEL) is becoming a key device in high-speed optical local-area networks (LANs) and even wide-area networks (WANs). This device is also enabling ultra parallel data transfer in equipment and computer systems. In this paper, we will review its physics and the progress of technology covering the spectral band from infrared to ultraviolet by featuring materials, fabrication technology, and performances such as threshold, output power, polarization, modulation and reliability. Lastly, we will touch on its future prospects.

Nonlinear characteristics of a DBR (Distributed Bragg Reflector) Cherenkov laser are investigated with the aid of particle simulation, allowing for the nonlinear properties of the electron beam. Numerical results show that the EM power extracted from the cavity is considerably suppressed by the nonlinear effect of the electron beam. Additionally, the extracted EM power is found to be critically dependent on the reflection coefficient of the DBR at the output end. Thus the DBRs at both ends of the cavity should be carefully designed in order to extract the EM power from the cavity efficiently.

Investigations were carried out on metalorganic-chemical-vapor-deposition (MOCVD)-grown strained AlGaN/ GaN/sapphire structures using X-ray diffratometry. While AlGaN with lower AlN molar fraction (< 0.1) is under the in-plane compressive stress, it is under the in-plane tensile stress with high AlN molar fraction (> 0.1). Though tensile stress caused the cracks in AlGaN layer with high AlN molar fraction, we found that the cracks dramatically reduced when the GaN layer quality was not good. Using this technique, we fabricated a GaInN multi-quantum-well (MQW) surface emitting diodes were fabricated on 15 pairs of AlGaN/GaN distributed Bragg reflector (DBR) structures. The reflectivity of 15 pairs of AlGaN/GaN DBR structure has been shown as 75% at 435 nm. Considerably higher output power (1.5 times) has been observed for DBR based GaInN MQW LED when compared with non-DBR based MQW structures.

This paper reports on broad-range wavelength tuning characteristics of DBR lasers which make use of a newly proposed multiple-phase-shift super structure grating (SSG). The reflection characteristics of the SSG reflector are analyzed theoretically. We found that the SSG reflector has periodic sharp reflection peaks each with high reflectivities thus making it a suitable wavelength selective reflector for single-mode lasers. The expected characteristics were evident in multiple-phase-shift SSGs fabricated using a new method which involves multiple-phase-shift insertion. DBR lasers with multiple-phase-shift SSGs were fabricated and their wavelength tuning characteristics were studied. The maximum tuning range is 105 nm in the single longitudinal mode under a CW condition. Dynamic single mode operation was also observed throughout the tuning range.