Devices for transmitting a modulated optical signal using a few-mode fiber

Patent metadata

Field	Value
Publication number	US-10969611-B2
Application number	US-201816036593-A
Country	US
Kind code	B2
Filing date	Jul 16, 2018
Priority date	Jul 14, 2017
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

A microwave photonic filter is provided. The filter includes an optical source, an electro-optic modulator, a single mode optical fiber, a few-mode optical fiber, and a photodiode. The electro-optic modulator is configured to receive an optical carrier from the optical source and an input electrical signal. The electro-optic modulator modulates the optical carrier based on the input electrical signal. The single mode optical fiber is configured to receive the modulated optical carrier from the electro-optic modulator. The few-mode optical fiber is configured to receive the modulated optical carrier from the single mode optical fiber. The filter includes one of a plurality of methods for causing higher order mode excitation in the few-mode fiber. The photodiode is configured to receive an output from the few-mode optical fiber.

First claim

What is claimed is:

1. A microwave photonic filter, comprising:
an optical source;
an electro-optic modulator configured to receive an optical carrier from the optical source and an input electrical signal, wherein the electro-optic modulator modulates the optical carrier based on the input electrical signal;
a single mode optical fiber configured to receive the modulated optical carrier from the electro-optic modulator;
a few-mode optical fiber configured to receive the modulated optical carrier from the single mode optical fiber;
a mode converter configured to generate at least one higher excitation mode in the few-mode optical fiber; and
a photodiode configured to receive an output from the few-mode optical fiber,
wherein the mode converter is a piezoelectric device attached to the few-mode optical fiber and constructed to induce acoustic waves in the few-mode optical fiber.

2. The filter according to claim 1 , wherein a wavelength of the induced acoustic waves corresponds to a spatial beat length between modes of the few-mode optical fiber.

3. The filter according to claim 1 , wherein the optical carrier is a laser beam.

4. The filter according to claim 1 , wherein the electro-optic modulator is one of: a quadrature-based Mach-Zehnder modulator or an EOSpace AX intensity modulator.

5. The filter according to claim 1 , wherein the few-mode optical fiber is a four mode optical fiber.

6. The filter according to claim 1 , wherein the few-mode optical fiber is a two mode optical fiber.

7. The filter according to claim 1 , wherein the acoustic waves are transverse or longitudinal acoustic waves.

Assignees

• Us Gov Sec Navy

Inventors

• Nickel Daniel V
• Haas Bryan

Classifications

• G02F2201/05

  multimode · CPC title

• G02F1/0115 Primary

  in optical fibres · CPC title

• H04B10/25

  Arrangements specific to fibre transmission · CPC title

• G02F2201/04

  monomode · CPC title

• H04B2210/006

  Devices for generating or processing an RF signal by optical means · CPC title