Abstract: The present application relates to a method of fabricating planar circuits using a photo lithographic mask set, to the photo lithographic mask set, and to a planar circuit fabricated with the photo lithographic mask set. The instant invention involves separating a photo lithographic 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 photo lithographic 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: 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 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 planar waveguide Mach-Zehnder interferometer (MZ) has improved performance as a variable optical attenuator as well as a thermo-optic switch (TOS) with reduced polarization dependent loss (PDL) in high attenuation states. The PDL was reduced by correcting for the increased birefringence that occurs on heating one waveguide arm by making the two waveguides inherently asymmetric, such that when one of the waveguides is heated, the differential birefringence of the two arms becomes zero. This asymmetry can be realized simply by changing the width of one of the waveguides. The modified device allows for very small PDL in the high attenuation state of a VOA and for theoretically perfect contrast in a TOS in the off state, with only a small penalty in PDL of the on state.

Abstract: A planar waveguide Mach-Zehnder interferometer (MZ) has improved performance as a variable optical attenuator as well as a thermo-optic switch (TOS) with reduced polarization dependent loss (PDL) in high attenuation states. The PDL was reduced by correcting for the increased birefringence that occurs on heating one waveguide arm by making the two waveguides inherently asymmetric, such that when one of the waveguides is heated, the differential birefringence of the two arms becomes zero. This asymmetry can be realized simply by changing the width of one of the waveguides. The modified device allows for very small PDL in the high attenuation state of a VOA and for theoretically perfect contrast in a TOS in the off state, with only a small penalty in PDL of the on state.

Abstract: Planar waveguide devices are described which function as elements of a soliton transmission communications system operating at a selected central wavelength. These devices have at least one optical channel waveguide whose core has a refractive index and dielectric constant with a dependence on the optical signal intensity which can balance a negative dispersion in the waveguide at dimensions compatible with monomode transmission of the selected central wavelength. It is a property of such a waveguide that if the input is an optical soliton, the output will also be a soliton. Such circuits are useful at the input and output of a soliton transmitting fiber as part of a high bit-rate (broadband) communications system.

Abstract: A planar waveguide device is described which can function as either a switching or power dividing element of a soliton transmission communication system operating at a selected central wavelength. The device has one input and two outputs and consists of two optical channel waveguides, in a coupler-like configuration, each of whose cores has a refractive index and dielectric constant with a dependence on the optical signal intensity which can balance a negative dispersion in the waveguide at dimensions compatible with monomode transmission of the selected central wavelength. It is a property of such waveguides that if the input to one channel waveguide is a temporal optical soliton, the output will also be a temporal soliton, and the output waveguide, or waveguides, from which it exits the device as well as the power of the switched or power divided signal at each output will be dependent upon the input soliton peak power.