Photonic integrated circuits based on quantum cascade structures

Patent metadata

Field	Value
Publication number	US-9450053-B2
Application number	US-201313951240-A
Country	US
Kind code	B2
Filing date	Jul 25, 2013
Priority date	Jul 26, 2012
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

Photonic integrated circuits (PICs) are based on quantum cascade (QC) structures. In embodiment methods and corresponding devices, a QC layer in a wave confinement region of an integrated multi-layer semiconductor structure capable of producing optical gain is depleted of free charge carriers to create a low-loss optical wave confinement region in a portion of the structure. Ion implantation may be used to create energetically deep trap levels to trap free charge carriers. Other embodiments include modifying a region of a passive, depleted QC structure to produce an active region capable of optical gain. Gain or loss may also be modified by partially depleting or enhancing free charge carrier density. QC lasers and amplifiers may be integrated monolithically with each other or with passive waveguides and other passive devices in a self-aligned manner. Embodiments overcome challenges of high cost, complex fabrication, and coupling loss involved with material re-growth methods.

First claim

What is claimed is:

1. A device comprising:
an integrated multi-layer semiconductor structure comprising an active portion and a passive portion, the multi-layer structure further comprising a wave confinement region, including a quantum cascade layer, the wave confinement region extending into the active and passive portions of the structure,
the quantum cascade layer within the wave confinement region in the active portion of the structure having a density of free charge carriers sufficient to produce optical gain in the quantum cascade layer in a wavelength spectrum, and
the quantum cascade layer within the wave confinement region in the passive portion of the structure having low loss in the wavelength spectrum and being substantially devoid of free charge carriers.

2. The device of claim 1 , wherein the quantum cascade layer within the wave confinement region in the passive portion of the structure is substantially devoid of free charge carriers by ion implantation.

3. The device of claim 2 , wherein the quantum cascade layer within the wave confinement region in the passive portion of the structure is substantially devoid of free charge carriers by ion implantation of ions of at least one of Hydrogen, Iron, Helium, Oxygen, Chromium, Cobalt, Nickel, Titanium, Vanadium, Silicon, Sulfur, Selenium, Tellurium, Tin, Zinc, and Carbon.

4. The device of claim 1 , wherein a density of the free charge carriers in the quantum cascade layer within the wave confinement region in the passive portion of the structure is less than about 10 15 cm −3 .

5. The device of claim 4 , wherein the density of the free charge carriers in the quantum cascade layer within the wave confinement region in the passive portion of the structure is less than about 10 10 cm −3 .

6. The device of claim 1 , wherein the active portion of the multi-layer structure is configured to include at least one of a laser, a distributed feedback laser, an amplifier, a master-oscillator power amplifier, a switch, a modulator, a phase shifter, and a detector.

7. The device of claim 1 , wherein the passive portion of the multi-layer structure is configured to include at least one of a waveguide, a router, a splitter, a combiner, a coupler, a phase shifter, a multiplexer, an interferometer, a filter, a modulator, a switch, and a resonator.

8. The device of claim 1 , wherein the wavelength spectrum is in the mid-infrared wavelength region.

9. The device of claim 1 , wherein the quantum cascade layer within the wave confinement region of the passive portion of the structure is configured to include energetically deep trap levels.

10. The device of claim 1 , wherein the quantum cascade layer within the wave confinement region in the passive portion of the structure is substantially devoid of free charge carriers by atom diffusion.

11. A method of making the device of claim 1 , the method comprising:
forming the integrated multi-layer semiconductor structure including the wave confinement region comprising the quantum cascade layer, the quantum cascade layer within the wave confinement region having the density of free charge carriers sufficient to produce optical gain in the quantum cascade layer in the wavelength spectrum; and
configuring a first portion of the wave confinement region to be the passive portion by substantially depleting the quantum cascade layer within the first portion of the wave confinement region of free charge carriers to have the low loss in the wavelength spectrum, a remaining, second portion of the wave confinement region other than the passive portion comprising the active portion of the wave confinement region.

12. The method of claim 11 , wherein substantially depleting the quantum cascade layer within the portion of the wave confinement region of free charge carriers comprises implanting ions into the layer.

13. The method of claim 12 , wherein implanting ions comprises implanting ions of at least one of Hydrogen, Helium, Oxygen, Iron, Chromium, Cobalt, Nickel, Titanium, Vanadium, Silicon, Sulfur, Selenium, Tellurium, Tin, Zinc, and Carbon.

14. The method of claim 11 , wherein substantially depleting the quantum cascade layer within the first portion of the wave confinement region of free charge carriers comprises depleting the layer to a free charge carrier density less than about 10 15 cm −3 .

15. The method of claim 14 , wherein substantially depleting the quantum cascade layer within the first portion of the wave confinement region of free charge carriers further comprises depleting the layer to a free charge carrier density less than about 10 10 cm −3 .

16. The method of claim 11 , wherein forming the multi-layer structure comprises configuring the active portion of the structure to include at least one of a laser, a distributed feedback laser, an amplifier, a master-oscillator power amplifier, a switch, a modulator, a phase shifter, and a detector.

17. The method of claim 11 , further comprising configuring the passive portion of the multi-layer structure to include at least one of a waveguide, a router, a splitter, a combiner, a coupler, a phase shifter, a multiplexer, an interferometer, a filter, a modulator, a switch, and a resonator.

18. The method of claim 11 , wherein the wavelength spectrum is in the mid-infrared wavelength region.

19. The method of claim 11 , wherein configuring the first portion of the wave confinement region to be the passive portion comprises configuring the quantum cascade layer within the first portion of the wave confinement region to include energetically deep trap levels to trap the free charge carriers.

20. The method of claim 11 , wherein substantially depleting the quantum cascade layer of free charge carriers comprises diffusing atoms into the layer.

21. The method of claim 11 , wherein forming the multi-layer structure comprises forming substrate, lower cladding, and upper cladding layers.

22. The method of claim 21 , wherein forming the multi-layer structure further comprises forming a contact layer, the method further comprising removing the contact layer in the passive portion of the multi-layer structure.

23. The method of claim 22 , further comprising depositing a low-loss dielectric material onto the multi-layer structure in at least partial place of the removed contact layer in the passive portion of the structure.

24. The method of claim 21 , further comprising implanting protons into the lower cladding and upper cladding layers in the passive portion of the multi-layer structure.

25. The method of claim 21 , wherein depleting the quantum cascade layer of free charge carriers comprises implanting ions into the quantum cascade layer, the method further comprising implanting ions into the lower cladding layer in the passive portion of the multi-layer structure.

26. The method of claim 25 , wherein forming the upper cladding layer follows implanting the ions into the lower cladding and quantum cascade layers.

27. The method of claim 26 , wherein forming the multi-layer structure further comprises forming a contact layer, the method further comprising removing the contact layer in the passive portion of the multi-layer structure following forming the upper cladding and contact layers.

28. The method of claim 27 , further comprising removing the upper cladding layer in the passive portion of the multi-layer structure, the method further co

Assignees

• Massachusetts Inst Technology
• Pendar Tech Llc

Inventors

• Goyal Anish K
• Diehl Laurent
• Pfluegl Christian
• Wang Christine A
• Witinski Mark Francis

Classifications

• H01S5/3013

  AIIIBV compounds · CPC title

• H01S5/2018

  Optical confinement, e.g. absorbing-, reflecting- or waveguide-layers · CPC title

• H10D62/815

  of structures having periodic or quasi-periodic potential variation, e.g. superlattices or multiple quantum wells [MQW] · CPC title

• H01S5/2063

  obtained by particle bombardment · CPC title

• H01S5/2275

  mesa created by etching · CPC title