A microring resonator sensor device for sensitive detection of the explosive 1,3,5-trinitrotoluene (TNT) is presented. It is based on the combination of a silicon microring resonator and tailored receptor molecules.

A key device in all-optical networks is the optical filter. A ring resonator filter with an integrated semiconductor optical amplifier (SOA) on the basis of GaInAsP-InP has been investigated and fabricated. A required passband shape of loss-compensated ring resonator filters can be custom-designed by the use of multiple coupled resonators. Results of single-, double-, and triple-ring resonators with integrated SOAs with free spectral ranges of 12.5, 25, and 50 GHz, respectively, are presented. A box-like filter response is obtained by the double- and triple-ring resonators using specific coupling coefficient

The filter response of single-ring resonators with integrated semiconductor optical amplifiers based on GaInAsP-InP is presented. The devices with free spectral ranges of 25 and 50 GHz have the form of a racetrack. An on-off ratio of 20 dB, a full-width at half-maximum of 12 and 24 pm, a finesse of 17, and a Q factor of 130,000 and 65,000, respectively, have been achieved. The tuning to a specific wavelength is performed by using integrated Pt-resistors

A device concept for laterally extracting selected wavelength from an optical signal travelling along a waveguide, for operation in metropolitan area networks, is presented. The signal on the fundamental mode of a multimode photonic crystal waveguide is coupled to a higher-order mode, at a center frequency that spatially depends on the slowly varying guide parameters. The device is compact, intrinsically fault-tolerant, and can split any desired fraction of the signal for monitoring purpose. Characterizations by the internal light source technique validate the optical concept while an integrated device with four photodiodes qualifies its potential with respect to real-world applications

In coherent optical systems or sensors, polarization matching between the superposed beams must be assured. The tracking range of automatic polarization control systems should be endless, i.e., any resets of finite range retarders, which transform the polarization, should cause no significant intensity losses. A variety of experimental systems including a computer as feedback controller are described in this paper. They include the minimum configuration of three fixed eigenmode retarders. i.e., the orientation of birefringence cannot be changed. These retarders are realized by fiber squeezers. Errortolerant systems which contain more than the minimum number of elements, however, are better suited to cope with time variant retarder transfer functions, etc. A fourth Rber squeezer allows the losses of a nonideal system to be kept to only 0.07 dB. Finally for the first time a closed loop system with two integrated optical retarders is described. These retarders have variable eigenmodes, i.e., adjustable birefringence orientation. An optimization procedure helps to idealize the device behavior. The system has less than 0.15 dB intensity losses, coupling and attenuation not Included.