Broadband all-photonic spectrum shapers

Patent metadata

Field	Value
Publication number	US-11898911-B2
Application number	US-202217958097-A
Country	US
Kind code	B2
Filing date	Sep 30, 2022
Priority date	Sep 30, 2021
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A photonic integrated circuit including an input for receiving input electromagnetic radiation having a bandwidth greater than 60 nm; a spectral splitter splitting the electromagnetic radiation into a plurality of spectral channels; a modulator for modulating an amplitude and a phase of one or more of the spectral channels so as to form modulated outputs; and a spectral recombiner for combining the modulated outputs into a single output port outputting output electromagnetic radiation having the desired output spectral intensity profile shaped by and synthesized from the modulated outputs.

First claim

What is claimed is:

1. A device useful as an arbitrary spectral shaper, comprising:
a photonic integrated circuit, comprising:
an input for receiving input electromagnetic radiation having a bandwidth greater than 60 nm;
a spectral splitter connected to the input, the spectral splitter splitting the electromagnetic radiation into a plurality of spectral channels each transmitting a different subband of the bandwidth, wherein at least one of the following: the bandwidth,

a spectral spacing of the spectral channels, the subband, or a number of the spectral channels is adjusted as a function of the spectral intensity profile of the input electromagnetic radiation and a desired output spectral intensity profile;
a modulator, connected to the spectral splitter, for modulating an amplitude and a phase of one or more of the spectral channels so as to form modulated outputs, wherein the modulator further comprises drop ports redirecting rejected portions of the electromagnetic radiation away from the photonic integrated circuit so as to suppress noise; and
a spectral recombiner, connected to the output of the modulator, for combining the modulated outputs into a single output port outputting output electromagnetic radiation having the desired output spectral intensity profile shaped by and synthesized from the modulated outputs.

2. The device of example 1, wherein the photonic integrated circuit is formed on a single substrate or chip, or multiple substrates or chips.

3. The device of claim 1 , wherein:
the spectral splitter and the recombiner each comprise a grating each having an output, and the modulator comprises:
a plurality of variable optical attenuators for modulating the amplitude, the variable optical attenuators each connected to a different one of the outputs of the spectral splitter and having a plurality of output ports and the drop ports; and a plurality of phase modulators connected to the variable optical attenuators, and each of the phase modulators connected to a different one of the variable optical attenuators and downstream to a different one of the array waveguide gratings inputs in the recombiner.

4. The device of claim 1 , wherein:
the modulator comprises an amplitude controller attenuating the amplitude of one or more of the spectral channels so as to form a plurality of attenuated spectral channels; and
the modulator further comprises a phase controller connected to the amplitude controller, wherein the phase controller shifts the phase of one or more of the spectral channels so as to form the modulated outputs each having their optical path lengths appropriately adjusted for the combining in the recombiner.

5. The device of claim 1 , wherein, for a subset of the subbands comprising region(s) of the spectral intensity profile varying over a spectral scale smaller than the subbands:
the subbands are smaller, and/or the number of the spectral channels transmitting the subset of the subbands is

increased, so that the regions of the spectral intensity profile are modulated with higher
resolution.

6. The device of claim 1 , wherein the modulator comprises:
an amplitude controller comprising one or more interferometers comprising

coupled pairs of waveguides, or a nonlinear crystal modulator modulating the amplitude
using an electrooptic or piezo-switching effect.

7. The device of claim 6 , wherein:
the amplitude controller comprises a plurality of electrodes, and each of the electrodes are coupled to the nonlinear crystal or one of the waveguides in each of the pairs.

8. The circuit of claim 7 , wherein the electrodes are thermally or electrically coupled to the waveguides so as to modulate phase, and thereby the amplitude transmitted by the amplitude modulator, in response to resistive heating, piezoelectric actuation, or electro-optic actuation of the electrodes controlled by control signals applied to the electrodes.

9. The device of claim 8 , further comprising a driving circuit coupled to the electrodes, the driving circuit outputting the control signals controlling the modulation of the amplitude and/or the phase of one or more of the spectral channels so as to form the desired output spectral intensity profile.

10. The device of claim 9 , further comprising:
a spectrum analyzer for measuring a frequency spectrum of the output electromagnetic radiation; and
a computer or control circuit coupled to the driving circuit and the spectrum analyzer, the control circuit determining the control signals from feedback comprising the frequency spectrum.

11. The device of claim 1 , wherein the input electromagnetic radiation comprises a plurality of wavelengths between 380-2500 nm and the spectral channels each transmit the subband having a wavelength spread in a range of 0.5 nm-100 nm.

12. The device of claim 11 , wherein the number of the spectral channels, the subband of each spectral channel, and the spacing between the spectral channels, are adjusted such that the output power of the output electromagnetic radiation varies across its entire bandwidth by less than 5 dB.

13. The device of claim 3 , wherein the gratings each comprise an arrayed waveguide gratings or echelle gratings.

14. A system comprising:
a laser frequency comb (LFC), a laser, or a communications network, or a spectrometer coupled to the device of claim 1 , wherein the system transmits the input electromagnetic radiation to the input and/or receives the output electromagnetic radiation from the single output port.

15. The system of claim 14 , wherein the system comprises the spectrometer and the output electromagnetic radiation has the desired output spectral intensity profile tailored for an interaction with a pre-determined molecular species.

16. An arbitrary spectral shaper comprising the device of claim 1 .

17. A gain flattening filter comprising the device of claim 1 .

18. An optical switch comprising the device of claim 1 .

19. The device of claim 1 , wherein the spectral channels comprise cascaded spectral channels wherein a plurality of the spectral channels are further split into an additional stage of sub-channels comprising narrower subbands and each having their amplitude and their phase individually modulated by the modulator.

20. The device of claim 1 , wherein the drop ports couple the rejected portions of the electromagnetic radiation to a spectrum analyzer for measurement of the frequency spectrum of the desired output spectral intensity profile.

Assignees

• California Inst Of Techn
• Observatoire De La Cote Dazur

Inventors

• Jovanovic Nemanja
• Jewell Jeffrey B
• Gatkine Pradip R
• Vasisht Gautam
• Beichman Charles A
• Cvetojevic Nick

Classifications

• G01J3/28 Primary

  Investigating the spectrum (using colour filters G01J3/51) · CPC title

• G01J3/12

  Generating the spectrum; Monochromators · CPC title

• G02F1/212

  Mach-Zehnder type · CPC title

• G02F1/225 Primary

  in an optical waveguide structure · CPC title

• G01J3/10

  Arrangements of light sources specially adapted for spectrometry or colorimetry · CPC title