Electro-absorption modulator with improved photocurrent uniformity
AssigneeJuniper Networks, Inc.
InventorJohn Parker
Life of this patent
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Abstract
Disclosed are integrated electro-absorption modulators (EAM) that are structured and/or operated to improve uniformity of the photocurrent density along the active region. In various embodiments, this improvement results from increased optical absorption at the rear of the EAM, e.g., as achieved by heating a region at the rear, increasing a bias voltage applied across the EAM towards the rear, or changing a material composition of an intrinsic layer towards the rear. In another embodiment, the improvement is achieved by coupling light from a waveguide into the EAM active region continuously along a length of the EAM, using overlap between a tapered section of the waveguide and the EAM.
Claims20
An integrated electro-absorption modulator comprising:
- a layered vertical diode structure formed above a device layer of a substrate, the diode structure comprising a bottom diode layer, an intrinsic diode layer, and a top diode layer that are vertically stacked;
- a waveguide formed in the device layer underneath the layered diode structure to couple light in and out of the intrinsic diode layer;
- multiple pairs of electrical terminals contacting the top and bottom diode layers in multiple contact regions within an active region, the multiple contact regions separated by isolating regions;
- and
- a driver circuit connected between the multiple pairs of electrical terminals and configured to apply multiple respective direct-current bias voltages across the layered diode structure in the respective contact regions.
A method of calibrating an integrated electro-absorption modulator, the integrated electro-absorption modulator comprising a layered diode structure, a waveguide, multiple pairs of electrical terminals contacting the layered diode structure in multiple contact regions within an active region, the multiple contact regions separated by isolating regions, and a driver circuit connected between the multiple pairs of electrical terminals and configured to apply multiple respective direct-current bias voltages across the layered diode structure in the respective contact regions, the method comprising:
- measuring an insertion loss of the integrated electro-absorption modulator and adjusting one of the direct-current bias voltages until a target insertion loss is reached;
- tuning a set of adjustable operating parameters of the integrated electro-absorption modulator across a tuning range while maintaining the target insertion loss, and measuring an optical modulation amplitude for multiple values of the set of adjustable operating parameters to determine a set of operating parameter values associated with a maximum optical modulation amplitude;
- and
- setting the adjustable operating parameters to the determined set of operating parameter values.
An integrated electro-absorption modulator comprising:
- a layered vertical diode structure above a device layer of a substrate, the layered vertical diode structure comprising a bottom diode layer, an intrinsic diode layer, and a top diode layer stacked vertically;
- means for coupling light in and out of the intrinsic diode layer and guiding the light within the device layer;
- multiple pairs of electrical terminals contacting the top and bottom diode layers in multiple contact regions within an active region, the multiple contact regions separated by isolating regions;
- and
- means for applying multiple respective direct-current bias voltages across the layered diode structure in the respective contact regions.
Dependencies are inferred from the claim text.