# US 12,216,318 B2 · Optical bridging element for separately stacked electrical ICs

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- Number: US 12,216,318 B2
- Document ID: US12216318B2
- Status: Granted
- Kind: B2
- Application number: 18/610,502
- Filed: 2024-03-20
- Published: 2024-07-04
- Granted: 2025-02-04
- Earliest claimed: 2022-03-18
- Assignees: Celestial AI Inc.
- Applicants: Celestial AI Inc.
- Inventors: Philip Winterbottom; David Lazovsky; Ankur Aggarwal; Martinus Bos; Subal Sahni
- Web page: https://patentgrep.com/patent/US12216318B2

## CPC

- G02B 6/4295: {coupling with semiconductor devices activated by light through the light guide, e.g. thyristors, phototransistors}
- G01K 7/023: {provided with specially adapted connectors (connectors per se H01R)}
- G01K 7/028: {using microstructures, e.g. made of silicon}
- G01K 7/14: Arrangements for modifying the output characteristic, e.g. linearising
- G02B 6/4246: {Bidirectionally operating package structures}
- G02B 6/4274: {Electrical aspects (G02B6/4263 and G02B6/4265 take precedence)}
- G02B 6/428: {containing printed circuit boards [PCB]}
- G02B 6/43: Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
- G02F 1/0113: {Glass-based, e.g. silica-based, optical waveguides}
- G02F 1/0123: {Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops}
- G02F 1/0157: {using electro-absorption effects, e.g. Franz-Keldysh [FK] effect or quantum confined stark effect [QCSE]}
- H04B 10/40: Transceivers
- H04B 10/801: {using optical interconnects, e.g. light coupled isolators, circuit board interconnections}
- G02B 6/4245: {Mounting of the opto-electronic elements}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H04B: TRANSMISSION

## Abstract

A package includes a first die with a bridging element with a first interconnect region, a first photonic transceiver portion, a second interconnect region, a first photonic path to an optical interface (OI), and a second photonic path from the OI to the first photonic transceiver portion. The first interconnect region electrically couples the first photonic transceiver portion to a second photonic transceiver portion in an analog/mixed-signal die (AMS die), while the second interconnect region connects a third photonic transceiver portion in a general die to the second photonic transceiver portion using an electrical coupling embedded in the first die. The electrical interconnects in the first interconnect region are less than two millimeters in length.

## Claims

### Claim 1

A package with a first die, the first die comprising:
a first interconnect region;
a first photonic transceiver portion electrically coupled with the first interconnect region;
a second interconnect region electrically coupled with the first interconnect region via an electrical coupling included in the first die;
a first photonic path from the first photonic transceiver portion to an optical interface (OI); and
a second photonic path from the OI to the first photonic transceiver portion;
wherein:
the first interconnect region is configured to electrically couple the first photonic transceiver portion to a second photonic transceiver portion residing in an analog/mixed-signal die (an AMS die);
the second interconnect region is configured to electrically couple an interface (I/F1), residing in a general die, to the second photonic transceiver portion; and
electrical interconnects in the first interconnect region are less than two millimeters (2 mm) in length.

### Claim 2 (depends on 1)

The package of claim 1, wherein:
the AMS die is stacked on top of the first die and the general die is separately stacked on top of the first die less than about two millimeters (2 mm) from and side by side with the AMS die.

### Claim 3 (depends on 2)

The package of claim 2, wherein:
the second photonic transceiver portion in the AMS die comprises a first driver (DRV1) and a first transimpedance amplifier (TIA1);
an AMS die first interconnect region is electrically and physically coupled with the first interconnect region via first electrical interconnects;
the interface (I/F1) is electrically coupled with a general die first interconnect region; and
the general die first interconnect region is electrically and physically coupled with the second interconnect region via second electrical interconnects.

### Claim 4 (depends on 3)

The package of claim 3, wherein:
signals between the first photonic transceiver portion, the second photonic transceiver portion, and the interface (I/F1) use a bus protocol according to a UCle and/or PCIe standard.

### Claim 5 (depends on 1)

The package of claim 1, wherein the first die is a photonic integrated circuit (PIC) and the AMS die and the general die are electric integrated circuits (EICs).

### Claim 6 (depends on 1)

The package of claim 1, wherein the optical interface (OI) comprises a fiber array unit (FAU) and a grating coupler (GC).

### Claim 7 (depends on 1)

The package of claim 1, wherein the first photonic transceiver portion comprises:
a first optical modulator (MOD1) coupled between the first interconnect region and the first photonic path; and
a first photodetector (PD1) coupled between the first interconnect region and the second photonic path.

### Claim 8 (depends on 7)

The package of claim 7, wherein the first die further comprises:
an optical multiplexer (MUX) optically coupled between MOD1 and the OI; and
an optical demultiplexer (DEMUX) optically coupled between the OI and PD1.

### Claim 9 (depends on 1)

The package of claim 1, wherein:
the first die further comprises:
a second optical modulator (MOD2);
a second photodetector (PD2);
a third interconnect region coupled with MOD2 and PD2; and
wherein the package further comprises a second die with a second die first interconnection region electrically and physically coupled with the third interconnect region via third electrical interconnects.

### Claim 10 (depends on 1)

The package of claim 1, further comprising:
a light engine configured to interface with the first die via fibers.

### Claim 11 (depends on 1)

The package of claim 1, wherein:
the OI is configured to interface with an external device optical interface.