公开(公告)号：US11082280B2

公开(公告)日：2021-08-03

申请号：US16594640

申请日：2019-10-07

Applicant: Google LLC

Inventor： Hong Liu ,  Xiang Zhou

IPC: H04L27/38 ,  H04L5/00 ,  H04L27/00 ,  H04B10/079 ,  H04B10/61 ,  H04B10/548 ,  H04B10/516 ,  H04L1/00 ,  H04L1/20

Abstract: System for adjusting a reference constellation for demodulating an optical signal include a coherent electro-optical receiver configured to convert a received optical signal to a plurality of electrical signals, an array of analog-to-digital convertors configured to digitize the plurality of electrical signals, and processor logic. The processor logic is configured to process the digitized plurality of electrical signals using a reference constellation to yield a plurality of decoded signals and a signal quality measurement. The reference constellation includes an inphase component equal to an ideal inphase component plus an inphase offset and a quadrature component equal to an ideal quadrature component plus a quadrature offset. The processor logic is configured to determine an optimal inphase offset and optimal quadrature offset. The processor logic is configured to update the reference constellation using the optimal inphase offset and the optimal quadrature offset.

公开(公告)号：US11075699B2

公开(公告)日：2021-07-27

申请号：US16939555

申请日：2020-07-27

Applicant: Google LLC

Inventor： Xiang Zhou ,  Hong Liu

IPC: H04B10/00 ,  H04B10/516 ,  H04B10/079 ,  H04B10/275 ,  H04B10/60

Abstract: Systems and methods are disclosed herein for coherently modulating and demodulating coherent optical signals using 5-bit constellations. The 5-bit constellations have improved suitability for short reach optical communications systems. A first 5-bit constellation can be formed from four rings. The first and fourth rings can form quadrature phase-shift keyed four-symbol sub-constellations, and the second and third rings can form phase-shift keyed twelve symbol constellations. Symbols from the third and fourth sub-constellations are arranged to form a square. A second 5-bit constellation can include an inner 16 symbol sub-constellation and an sixteen symbol outer sub-constellation. Each of the symbols of the inner sub-constellation are equally spaced from its nearest neighboring symbols along both the quadrature and in-phase axes. Each of the symbols in the outer constellation has an equal euclidean-distance with its nearest neighboring symbols in the outer sub-constellation.

公开(公告)号：US20210211203A1

公开(公告)日：2021-07-08

申请号：US17206854

申请日：2021-03-19

Applicant: Google LLC

Inventor： Xiang Zhou ,  Hong Liu

IPC: H04B10/556 ,  H04J14/06 ,  H04B10/524 ,  H04B10/2507 ,  H04B10/54

Abstract: A receiver system is provided for receiving a coherent Pulse Amplitude Modulation (PAM) encoded signal. The receiver system may include an optical polarization component configured to modulate a polarization of the received coherent PAM encoded signal. The receiver system may further include a digital signal processor (DSP) configured to perform polarization recovery between the received coherent PAM encoded signal and the LO signal using a first control loop, and to perform phase recovery between the received coherent PAM encoded signal and the LO signal using a second control loop.

公开(公告)号：US10778337B1

公开(公告)日：2020-09-15

申请号：US16415792

申请日：2019-05-17

Applicant: Google LLC

Inventor： Xiang Zhou ,  Hong Liu

IPC: H04B10/00 ,  H04B10/516 ,  H04B10/60 ,  H04B10/275 ,  H04B10/079

Abstract: Systems and methods are disclosed herein for coherently modulating and demodulating coherent optical signals using 5-bit constellations. The 5-bit constellations have improved suitability for short reach optical communications systems. A first 5-bit constellation can be formed from four rings. The first and fourth rings can form quadrature phase-shift keyed four-symbol sub-constellations, and the second and third rings can form phase-shift keyed twelve symbol constellations. Symbols from the third and fourth sub-constellations are arranged to form a square. A second 5-bit constellation can include an inner 16 symbol sub-constellation and an sixteen symbol outer sub-constellation. Each of the symbols of the inner sub-constellation are equally spaced from its nearest neighboring symbols along both the quadrature and in-phase axes. Each of the symbols in the outer constellation has an equal euclidean-distance with its nearest neighboring symbols in the outer sub-constellation.

公开(公告)号：US20190171029A1

公开(公告)日：2019-06-06

申请号：US15975268

申请日：2018-05-09

Applicant: Google LLC

Inventor： Ryohei Urata ,  Lieven Verslegers ,  Hong Liu ,  Daoyi Wang

IPC: G02B27/28 ,  G02B6/10 ,  G02B6/126 ,  G02B27/09

Abstract: A photonic integrated circulator can be fabricated by including a plurality of polarizing beam splitters and optical polarization rotators such that two copies of the optical signal are output at a receiver in substantially aligned polarization states. The circulator can be used for facilitating bi-directional communications between photonic integrated circuit devices, which are inherently polarization sensitive, while reducing signal loss.