Abstract: Systems and methods for stripping an optical mode from a semiconductor laser. A waveguide layer with multiple layers is included in the semiconductor laser and is typically arranged beneath the active region. The waveguide layer is configured to match the phase of the second order mode. The waveguide layer does not substantially match the primary optical mode of the laser. By matching the phase of the second order mode, the confinement of the second order mode is reduced and the second order mode strongly couples with the waveguide layer. The optical confinement of the primary mode is not substantially reduced. The side-mode suppression ratio is thereby improved by stripping the second order mode from the active region.

Abstract: Systems and methods for controlling edge gain in avalanche photodiodes. During fabrication of an avalanche photodiode, the photodiode is diffused with a dopant. The mask used for the dopant includes a plurality of openings such that the dopant diffuses within the photodiode to create a plurality of interconnected spheres. The diffusion front has a shape to introduce an edge effect into the center of the photodiode. The diffusion front ameliorates the edge effect by introducing the edge effect into the center of the photodiode.

Abstract: This disclosure is concerned with starved source diffusion methods for forming avalanche photodiodes are provided for controlling an edge effect. In one example, a method for manufacturing an avalanche photodiode includes forming an absorber layer and an avalanche layer over a substrate. Next, a patterned mask defining one or more openings is formed over a surface of the avalanche layer. Finally, a dopant is deposited over the patterned mask and the avalanche layer such that the dopant is blocked by the patterned mask but diffuses into the avalanche layer in areas where the patterned mask defines an opening. The patterned mask is configured such that the depth to which the dopant diffuses into the avalanche layer varies so as to form a sloped diffusion front in the avalanche layer.

Abstract: Starved source diffusion methods for forming avalanche photodiodes (APDs) are provided for controlling the edge effect. The edge effect is controlled by reducing edge gain near the edges of an APD active region. This is accomplished by creating a sloped diffusion front near the edges of the active region. The sloped diffusion front is advantageously formed in a single doping step by using a patterned mask during doping. The patterned mask reduces the depth to which dopants diffuse in areas where it only partly covers the underlying layer. By covering more of the underlying layer nearer the edge and progressively less towards the center, the sloped diffusion front is formed. The shallower diffusion depth near the edge reduces the edge gain, and therefore the edge effect. As a result, an APD to fiber misalignment is less likely, and possibility of edge breakdown is greatly reduced.

Abstract: Systems and methods for tuning a DBR stack for an optical amplifier. The DBR layers in a mirror of the optical amplifier have a duty cycle that can be altered to tune a location of a channel drop in a gain spectrum. In addition to changing the duty cycle, the DBR stacks can be segmented. The segmented DBR stacks and/or the selected duty cycle tunes a location of a channel drop outside of a range of wavelengths of interest.

Abstract: Systems and methods for expanding an optical mode of a laser or optical amplifier to reduce leakage current. A waveguide layer is included in a laser that optically couples with the active region. The waveguide layer is configured to expand the optical mode into the layers beneath the active region. This enables the thickness of the layers above the active region to be reduced, thereby reducing leakage current. Because the waveguide layer expanded the optical mode without substantially reducing the optical confinement of the active region, the optical loss associated with the metal contact is also reduced even though the layers between the active region and the metal contact have been thinned. In one embodiment, the threshold current is reduced.

Abstract: Systems and methods for stripping an optical mode from a semiconductor laser. A waveguide layer is included in the semiconductor laser and is typically arranged beneath the active region. The waveguide layer is configured to match the phase of the second order mode. The waveguide layer does not substantially match the primary optical mode of the laser. By matching the phase of the second order mode, the confinement of the second order mode is reduced and the second order mode strongly couples with the waveguide layer. The optical confinement of the primary mode is not substantially reduced. The side-mode suppression ratio is thereby improved by stripping the second order mode from the active region.

Abstract: Systems and methods for extending a linear range of a semiconductor optical amplifier (SOA). A feedback layer is included in an SOA. The optical mode of the SOA is distributed between the feedback layer and the active region. As output optical power increases, the mode confinement of the active region increases and the mode is drawn from the feedback layer into the active region. The increase in the mode confinement offsets a loss of material gain such that the linear range of the SOA is extended. In one embodiment, the modal gain increases an higher output optical powers.