Linearized optical digital-to-analog modulator

• US 10,033,465 B2
• Filed: 10/20/2016
• Issued: 07/24/2018
• Est. Priority Date: 06/13/2007
• Status: Active Grant

• Current Assignee: Ramot at Tel Aviv University Limited (Tel Aviv University)
• Original Assignee: Ramot at Tel Aviv University Limited (Tel Aviv University)
• Inventors: Ehrlichman, Yossef, Amrani, Ofer, Ruschin, Shlomo
• Primary Examiner(s): JEANGLAUDE, JEAN BRUNER
• Application Number:
  US15/298,327
• Publication Number:
  US 20170294968A1
• Time in Patent Office: 642 Days
• Field of Search: 341131, 356464, 398115, 398186
• CPC Class Codes: G02F 1/0121 Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/015 based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction G02F1/03 takes precedence
• CPC Class Codes: G02F 1/212 Mach-Zehnder type
• CPC Class Codes: G02F 1/225 in an optical waveguide structure
• CPC Class Codes: G02F 2203/19 linearised modulation; reduction of harmonic distortions
• CPC Class Codes: G02F 7/00 Optical analogue/digital converters
• CPC Class Codes: H03M 1/002 Provisions or arrangements for saving power, e.g. by allowing a sleep mode, using lower supply voltage for downstream stages, using multiple clock domains or by selectively turning on stages when needed
• CPC Class Codes: H03M 1/70 Automatic control for modifying converter range
• CPC Class Codes: H04B 10/2575 Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
• CPC Class Codes: H04B 10/25891 Transmission components H04B10/40 takes precedence
• CPC Class Codes: H04B 10/505 using external modulation
• CPC Class Codes: H04B 10/5055 using a pre-coder
• CPC Class Codes: H04B 10/516 Details of coding or modulation
• CPC Class Codes: H04B 10/541 Digital intensity or amplitude modulation
• CPC Class Codes: H04B 10/556 Digital modulation, e.g. differential phase shift keying [DPSK] or frequency shift keying [FSK]

Abstract

A system for converting digital data into a modulated optical signal, comprises an electrically controllable device having M actuating electrodes. The device provides an optical signal that is modulated in response to binary voltages applied to the actuating electrodes. The system also comprises a digital-to-digital converter that provides a mapping of input data words to binary actuation vectors of M bits and supplies the binary actuation vectors as M bits of binary actuation voltages to the M actuating electrodes, where M is larger than the number of bits in each input data word. The digital-to-digital converter is enabled to map each digital input data word to a binary actuation vector by selecting a binary actuation vector from a subset of binary actuation vectors available to represent each of the input data words.

Claims

1. A method for converting digital electrical data into modulated optical streams, said method comprising

inputting into an optical modulator N bits of digital data in parallel, N being larger than 1;

mapping a set of N input values corresponding to said N bits of digital data to a vector of M voltage values where M is equal to or larger than N;

driving at least M electrodes of the optical modulator, enabled to pulse modulate at least an input optical stream, responsively to the M voltage values, to provide at least a pulse modulated output optical stream.

2. The method of claim 1, wherein the M electrodes are distributed over a plurality of waveguide branches of the optical modulator and are enabled to modulate unmodulated optical input streams coupled to the waveguide branches.

3. A method of modulating and transmitting at least an optical signal over at least an optical fiber in response to N bits of digital data in parallel, the method comprising:

inputting the N bits of digital data into an optical modulator having a plurality of waveguide branches, where each branch has an input of an unmodulated optical signal;

converting the N bits of digital data to M drive voltage values, where M≥

N and N>

1;

coupling the M drive voltage values to the unmodulated optical signal, said coupling enabling pulse modulation of the unmodulated optical signal, thereby generating a pulse modulated optical signal;

transmitting the pulse modulated optical signals over at least an optical fiber.

4. A method for converting digital electrical data into modulated optical streams, said method comprising

inputting into an optical modulator N bits of digital data in parallel, N being larger than 1;

mapping a set of N input values corresponding to said N bits of digital data to a vector of M voltage values where M is equal to or larger than N;

driving at least M electrodes of the optical modulator, enabled to modulate by QAM at least an input optical stream, responsively to the M voltage values, to provide at least a QAM modulated output optical stream.

5. The method of claim 4, wherein the M electrodes are distributed over a plurality of waveguide branches of the optical modulator and are enabled to modulate unmodulated optical input streams coupled to the waveguide branches.

6. A method for converting N bits of digital data input to at least a modulated optical stream and transmitting at least the modulated optical stream, the method comprising:

inputting the N bits of digital data input in parallel into an optical modulator where N>

1;

converting the N bits of digital data input to a vector of M voltage values, where M≥

N;

inputting at least an unmodulated optical input stream into the optical modulator;

driving M electrodes that are enabled to pulse modulate at least the unmodulated optical input stream to generate at least a pulse modulated optical output stream responsive to the M voltage values; and

transmitting at least the pulse modulated optical output stream over at least an optical fiber.

7. The methods of claim 6, wherein the M electrodes are distributed over a plurality of waveguide branches and are enabled to modulate at least the unmodulated optical input stream coupled to the waveguide branches.

8. The method of claim 6, wherein each electrode of the M electrodes modulates at least the unmodulated optical input stream responsive to a single voltage value of the M voltage values.

9. A method of modulating one or more unmodulated optical signals according to one or more predetermined QAM constellations in response to N bits of parallel digital data input, and transmitting the one or more QAM modulated optical signals over one or more optical fibers, the method comprising:

inputting the N bits of digital data input into an optical modulator within a module also containing at least a light source, wherein the optical modulator comprises a plurality of waveguide branches for receiving one or more unmodulated optical signals and outputting one or more modulated optical signals;

converting the N bits of digital data input to M voltages, where M≥

N and N>

1 drive;

coupling the M drive voltages to the one or more unmodulated optical signals, using M actuating electrodes, said coupling causing modulation of the one or more unmodulated optical signals, wherein the optical modulator outputs one or more QAM modulated optical signals; and

transmitting the one or more QAM modulated optical signals over one or more optical fibers.

10. A method for converting N bits of digital data input to at least a modulated optical stream and transmitting at least the modulated optical stream, the method comprising:

inputting the N bits of digital data input in parallel into an optical modulator where N>

1;

converting the N bits of digital data input to a vector of M voltage values, where M≥

N;

inputting at least an unmodulated optical input stream into the optical modulator;

driving M electrodes that are enabled to modulate by QAM at least the unmodulated optical input stream to generate at least a QAM modulated optical output stream responsive to the M voltage values; and

transmitting at least the QAM modulated optical output stream over at least an optical fiber.

11. The methods of claim 10, wherein the M electrodes are distributed over a plurality of waveguide branches and are enabled to modulate at least the unmodulated optical input stream coupled to the waveguide branches.

12. The method of claim 10, wherein each electrode of the M electrodes modulates at least the unmodulated optical input stream responsive to a single voltage value of the M voltage values.

13. A method of modulating and transmitting at least an optical signal over at least an optical fiber in response to N bits of digital data in parallel, the method comprising:

inputting the N bits of digital data into an optical modulator having a plurality of waveguide branches, where each branch has an input of an unmodulated optical signal;

converting the N bits of digital data to M drive voltage values, where M≥

N and N>

1;

coupling the M drive voltage values to the unmodulated optical signal, said coupling enabling modulation of the unmodulated optical signal by QAM, thereby generating a QAM modulated optical signal;

transmitting the QAM modulated optical signals over at least an optical fiber.