Abstract: An electronic dispersion compensation (EDC) arrangement for a multi-channel optical receive utilizes a time division technique to “share” a common adaptive algorithm block between a plurality of N separate channels. The algorithm block embodies a specific algorithm associated with correcting/updating tap weights for the delay lines forming the equalizing elements, and a time slot assignment element is used in conjunction with the algorithm block to control the access of the various channels to the algorithm block. In situations where certain channels experience a greater degree of dispersion than others, the time slot assignment element may be configured to allot a greater number of time slots to the affected channels.

Abstract: A CMOS driver circuit is configured to provide a tri-state condition after a predetermined number of like-valued data bits have been transmitted, reducing the presence of intersymbol interference (ISI) along a transmission channel. In situations where the transmission channel is bandwidth-limited, the use of the tri-stating technique allows for the complete transition to the supply rails during the given bit period.

Abstract: A unitary optical receiver assembly is formed to include a V-groove passively aligned with a first aspheric lens (the lens formed along a surface perpendicular to the V-groove). An optical fiber is disposed along the V-groove and is used to bring the received optical signal into the unitary assembly. Upon passing through the first aspheric lens, the received optical signal will intercept a 45° turning mirror wall that directs the signal downward, through a second aspheric lens (also molded in the unitary assembly), and then into a photosensitive device. Advantageously, the photosensitive device is disposed in passive alignment with the second aspheric lens, allowing for a received signal to be coupled from an incoming optical fiber to a photosensitive device without needing any type of active alignment therebetween.

Abstract: The surface silicon layer (SOI layer) of an SOI-based optical modulator is processed to exhibit a corrugated surface along the direction of optical signal propagation. The required dielectric layer (i.e., relatively thin “gate oxide”) is formed over the corrugated structure in a manner that preserves the corrugated topology. A second silicon layer, required to form the modulator structure, is then formed over the gate oxide in a manner that follows the corrugated topology, where the overlapping portion of the corrugated SOI layer, gate oxide and second silicon layer defines the active region of the modulator. The utilization of the corrugated active region increases the area over which optical field intensity will overlap with the free carrier modulation region, improving the modulator's efficiency.

Abstract: An optical modulator is formed to include an adjustable drive arrangement for dynamically adjusting the effective length of the optical signals path(s) within the modulator. Each modulator arm is partitioned into a plurality of segments, with each segment coupled to a separate electrical signal driver. Therefore, the effective length of each modulator arm will be a function of the number of drivers that are activated for each arm at any given point in time. A feedback arrangement may be used with the plurality of drivers to dynamically adjust the operation of the modulator by measuring the extinction ratio as a function of optical power, turning “on” or “off” individual drivers accordingly.

Abstract: A method and structure for reducing optical signal loss in a silicon waveguide formed within a silicon-on-insulator (SOI) structure uses CMOS processing techniques to round the edges/corners of the silicon material along the extent of the waveguiding region. One exemplary set of processes utilizes an additional, sacrificial silicon layer that is subsequently etched to form silicon sidewall fillets along the optical waveguide, the fillets thus “rounding” the edges of the waveguide. Alternatively, the sacrificial silicon layer can be oxidized to consume a portion of the underlying silicon waveguide layer, also rounding the edges. Instead of using a sacrificial silicon layer, an oxidation-resistant layer may be patterned over a blanket silicon layer, the pattern defined to protect the optical waveguiding region.

Abstract: An optical modulator is formed to include a plurality of separate electrodes disposed along one arm, the electrodes having different lengths and driven with different signals to provide for multi-level signaling (e.g., PAM-4 signaling). By using separate drivers to energize the different sections, the number of sections energized at a given point in time will define the net phase shift introduced to the optical signal. The total length of the combined modulator sections is associated with a ? phase shift (180°). Each section is driven by either a digital “one” or “zero”, so as to create the multi-level modulation. An essentially equal change in power between adjacent transmitted symbols is accomplished by properly adjusting the lengths of each individual section.