Abstract: The invention relates to a variable optical attenuator constructed as a Mach Zehnder planar lightwave circuit, particularly including a channel waveguide support structure for heat isolation and stress relief to reduce polarization dependent loss (PDL) and power consumption in the device. Power reduction trenches comprise longitudinal segments having small stress relief pillars of cladding material left in between them in the etching process. The waveguides of the MZI are supported by a main pillar structure and integral stress relief pillars which remain after removal of the trenches. The waveguide is surrounded by air on three sides for improved heat isolation. The performance of the present invention shows substantial improvement in PDL and extinction ratio over the prior art continuous trench design, and also, to a smaller degree, over the case where power reduction trenches are not used at all.

Abstract: A flat-top arrayed waveguide grating with a Hyper-Gaussian distribution function and a modified sinc design exhibits a very low chromatic dispersion, low loss and requires a relatively small number of waveguides. Controlled loss is introduced into certain waveguides of the array by creating gaps (unguided regions) between the waveguides to produce a desired predetermined amplitude distribution. The gaps are preferably arranged in the middle of the array.

Abstract: The present application relates to a method of fabricating planar circuits using a photolithographic mask set, to the photolithographic mask set, and to a planar circuit fabricated with the photolithographic mask set. The instant invention involves separating a photolithographic mask into two parts, namely, a master mask and one or more slave masks. The master mask and the one or more slave masks form a photolithographic mask set that is used iteratively to fabricate the planar circuits. In particular, the master mask is used as a template to provide the general layout for the planar circuit, while each slave mask is varied to tune and/or tailor the planar circuit. Since only a small portion of the planar circuit is redesigned and/or rewritten as a new mask (i.e., the slave mask), the instant invention provides a simple and cost effective method for optimizing planar circuits.

Abstract: A demultiplexer/multiplexer is disclosed wherein an arrayed waveguide grating having a reflector at an end includes selectable signal path blockers. The arrayed waveguide device has a common input/output port for launching radiation in the form of an input signal having n wavelengths therein and for receiving back via the reflector at the input/output port a selected channel of the input signal. In operation a multiplexed signal have n channels is launched therein and a selected channel is output for analysis or further processing.

Abstract: A method for designing an arrayed waveguide grating that includes input and output couplers, input and output slabs, and a plurality of arms connecting the input and output slabs includes steps of determining a desired amplitude response for the arrayed waveguide grating. A desired dispersion response for the arrayed waveguide grating is determined. Input and output couplers are designed to produce the desired amplitude response. The lengths of the arms of the arrayed waveguide grating are perturbed to produce a flat or linear dispersion. In addition, the polarity of a group delay, dispersion and dispersion slope response of an arrayed waveguide grating can also be changed by adjusting Individual lengths of the waveguide arms. The group delay, dispersion and dispersion slope of a multiplexer and a demultiplexer can be matched to substantially cancel.

Abstract: A flat-top arrayed waveguide grating with a Hyper-Gaussian distribution function and a modified sinc design exhibits a very low chromatic dispersion, low loss and requires a relatively small number of waveguides. Controlled loss is introduced into certain waveguides of the array by creating gaps (unguided regions) between the waveguides to produce a desired predetermined amplitude distribution. The gaps are preferably arranged in the middle of the array.

Abstract: A method for designing an arrayed waveguide grating that includes input and output couplers, input and output slabs, and a plurality of arms connecting the input and output slabs includes steps of determining a desired amplitude response for the arrayed waveguide grating. A desired dispersion response for the arrayed waveguide grating is determined. Input and output couplers are designed to produce the desired amplitude response. The lengths of the arms of the arrayed waveguide grating are perturbed to produce a flat or linear dispersion. In addition, the polarity of a group delay, dispersion and dispersion slope response of an arrayed waveguide grating can also be changed by adjusting Individual lengths of the waveguide arms. The group delay, dispersion and dispersion slope of a multiplexer and a demultiplexer can be matched to substantially cancel.