On-chip high capacitance termination for transmitters
A modulator and a capacitor are integrated on a semiconductor substrate for modulating a laser beam. Integrating the capacitor on the substrate reduces parasitic inductance for high-speed optical communication.
1. A device for modulating light from a semiconductor laser, the device comprising:
a platform, wherein:
the platform comprises a substrate,
the platform is made of a first semiconductor material,
the platform comprises a first optical waveguide disposed in the first semiconductor material and integrated on the substrate, the first optical waveguide is a semiconductor optical waveguide
and
the platform comprises a ground plane integrated on the substrate;
a chip, wherein:
the chip is integrated on the substrate,
the chip is made of a second semiconductor material different from the first semiconductor material,
the chip comprises a second optical waveguide disposed in the second semiconductor material, and
the second optical waveguide is optically aligned with the first optical waveguide;
a contact, wherein:
the contact is integrated on the substrate, and
the contact is electrically connected with the chip; and
a capacitor, wherein:
the capacitor is integrated on the substrate, and
the capacitor is electrically connected with the contact.
2. The device as recited in claim 1 , wherein:
the chip is electrically between the contact and the ground plane, and
the capacitor is electrically between the contact and the ground plane.
3. The device as recited in claim 1 , further comprising a resistor electrically integrated on the substrate between the contact and the capacitor.
4. The device as recited in claim 1 , wherein the chip is electrically integrated on the substrate between the contact and the ground plane.
5. The device as recited in claim 1 , further comprising a bond securing the chip to the platform.
6. The device as recited in claim 5 , wherein the bond secures the chip to the substrate of the platform.
7. The device as recited in claim 5 , wherein the chip is bonded in a recess of the platform so that the chip is closer to the substrate than the first semiconductor waveguide is to the substrate.
8. The device as recited in claim 5 , wherein the second optical waveguide is optically aligned with the first optical waveguide by butt coupling.
9. The device as recited in claim 1 , wherein the chip comprises multi-quantum wells.
10. The device as recited in claim 1 , wherein the capacitor has a capacitance between 500 and 900 picofarads.
11. The device as recited in claim 1 , wherein the substrate is mounted on a printed circuit board.
12. The device as recited in claim 1 , wherein the capacitor is within 20, 50, 100, 200, 500, and/or 1,000 μm of the chip.
13. A method for creating a modulator for a semiconductor laser, the method comprising:
bonding a chip to a platform, wherein:
the platform comprises a substrate;
the platform is made of a first semiconductor material;
the platform comprises a first optical waveguide disposed in the first semiconductor material and integrated on the substrate; the first optical waveguide is a semiconductor optical waveguide
the chip is made of a second semiconductor material different from the first semiconductor material;
the chip comprises a second optical waveguide disposed in the second semiconductor material; and
the second optical waveguide is optically aligned with the first optical waveguide by the second optical waveguide being butt coupled to the first optical waveguide;
forming a contact integrated on the substrate, wherein the contact is electrically connected with the chip;
forming a ground plane integrated on the substrate, wherein the chip is electrically integrated on the substrate between the contact and the ground plane; and
bonding a capacitor to the platform, wherein:
the capacitor is integrated on the substrate, and
the capacitor is electrically connected with the contact.
14. The method of claim 13 , further comprising applying a modulation signal to the contact, wherein the chip is used as an electro absorption modulator.
15. The method of claim 13 , wherein the capacitor has a capacitance between 500 and 900 picofarads.