Fiber coupling using collimated beams
An optical interconnect uses large 2-dimensional matrices of optoelectronic chips. The optoelectronic chips are placed directly above the analog circuitry required to drive them and with the microlens array placed on top of the optoelectronic chip. A single microlens array is assembled directly on top of the 2-dimensional optoelectronic chip. The optoelectronic chips may include vertical cavity surface emitting lasers (VCSEL) for signal generation and p-i-n photodiodes for signal detection. A bundle of optical fibers or waveguides with a layout identical to the optoelectronic chips is used for optical data transfer between constituents of the optical communication system.
1. An optical interconnect apparatus comprising:
an integrated circuit chip;
a transmitting optoelectronic chip positioned on the integrated circuit chip, the transmitting optoelectronic chip including a first substrate and a 2-dimensional optoelectronic array of back-emitting laser diodes positioned on an underside of the first substrate for transmitting optical signals through the first substrate;
a receiving optoelectronic chip positioned on the integrated circuit chip adjacent the transmitting optoelectronic chip, the receiving optoelectronic chip including a second substrate and a 2-dimensional optoelectronic array of back-illuminated photodiodes positioned on an underside of the second substrate for receiving optical signals through the second substrate;
a first microlens array positioned on the transmitting optoelectronic chip, the first microlens array including a first plurality of microlenses each adhering directly to a top side of the first substrate opposite the array of laser diodes;
a second microlens array spaced above and optically coupled to the first microlens array;
a first bundle of optical fibers coupled to the second microlens array;
a third microlens array positioned on the receiving optoelectronic chip, the third microlens array including a second plurality of microlenses each adhering directly to a top side of the second substrate opposite the array of photodiodes;
a fourth microlens array spaced above and optically coupled to the third microlens array; and
a second bundle of optical fibers coupled to the fourth microlens array;
wherein the integrated circuit chip includes circuitry for controlling the transmitting and receiving optoelectronic chips;
wherein the first microlens array and the third microlens array have the same optical properties; and
wherein the first substrate has a thickness related to the optical properties of the first microlens array such that substantially all of the optical surface of each of the first plurality of microlenses is included in an optical path of the optical signals transmitted from the 2-dimensional optoelectronic array of laser diodes.
2. The optical interconnect apparatus of claim 1 , wherein the transmitting optoelectronic chip includes a VCSEL chip including a 2-dimensional array of vertical cavity surface emitting lasers.
3. The optical interconnect apparatus of claim 1 , wherein the receiving optoelectronic chip includes a p-i-n photodiode chip.
4. The optical interconnect apparatus of claim 1 , wherein the first microlens array includes III-IV material.
5. The optical interconnect apparatus of claim 4 , wherein the first microlens array includes GaP lenses.
6. The optical interconnect apparatus of claim 4 , wherein the second microlens array includes Pyrex.
7. The optical interconnect apparatus of claim 1 , wherein at least one of the transmitting and receiving optoelectronic chips is flip-chip bonded to the integrated circuit chip.
8. The optical interconnect apparatus of claim 1 , wherein the optoelectronic array on each optoelectronic chip is positioned along an optical axis of the corresponding bundle of optical fibers.
9. The optical interconnect apparatus of claim 1 , wherein the first microlens array and the second microlens array have inverse magnification values.