OPTICAL PHASE MODULATOR WITH SINUSOIDAL PN JUNCTION

• US 20190018263A1
• Filed: 07/10/2018
• Published: 01/17/2019
• Est. Priority Date: 07/11/2017
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Original Assignee: Commissariat a L'Energie Atomique (French Alternative Energies and Atomic Energy Commission)
• Inventors: Hassan, Karim, Boutami, Salim, Anfray, Thomas
• Granted Patent: US 10,409,094 B2
• Time in Patent Office: Days
• CPC Class Codes: G02F 1/01708 in an optical wavequide structure
• CPC Class Codes: G02F 1/0175 with a spatially varied well profile, e.g. graded or stepped quantum wells
• CPC Class Codes: G02F 1/025 in an optical waveguide structure G02F1/017, G02F1/2257 take precedence
• CPC Class Codes: G02F 1/2257 the optical waveguides being made of semiconducting material

Abstract

The object of the invention is a phase modulator including a modulation guide intended to guide die propagation of a light flow, said guide comprising a PN junction extending mainly along the main axis of propagation according to an oscillating continuous function. Advantageously, the oscillating continuous function is defined in such a way that the PN junction covers at least 50% of the light flow between the input and the output of the modulation guide. According to one possibility, the continuous function is sinusoidal. The object of the invention is also a switch and an intensity modulator each comprising a phase modulator.

Claims

1. A phase modulator for a light flow comprising:

an input guide and at least one multimode modulation guide having an input optically coupled with an output of the input guide, an output and a main axis (y) of propagation along which a light flow is intended to pass through the at least one multimode modulation guide, the at least one multimode modulation guide further comprising;

at least one P-doped zone and one N-doped zone in such a way as to define a PN junction generating a space charge region,

a device configured to vary a voltage V applied between the at least one N-doped and P-doped zones in such a way as to vary a phase of the light flow intended to propagate in the at least one multimode modulation guide,

wherein the input guide is configured to excite various propagation modes in the at least one multimode modulation guide and in that the PN junction extends mainly along the main axis (y) of propagation, following an oscillating continuous function fanning oscillations each defining a crest and in which the crests of two successive oscillations are separated by a distance P_jPN.

2. The phase modulator according to claim 1, wherein the oscillating continuous function is defined in such a way that the space charge region covers at least X % of the light flow between the input and the output of the at least one multimode modulation guide, with X≥

50.

3. The phase modulator according to claim 1, wherein the distance P_jPN is such that P_jPN≥

300 nm.

4. The phase modulator according to claim 1, wherein the oscillating continuous function is periodic, having a period P_jPN.

5. The phase modulator according to claim 1, wherein the input guide is configured in order for the light flow propagating in the at least one multimode modulation guide to have a power distribution oscillating in a periodic maimer according to a period P_flux, and the PN junction is configured, in such a way as to vary P_flux between a value P_fluxE at the input of the guide and a value P_fluxS at the output of the guide, said period P_fluxS being dependent on the voltage V, with Y varying between V_min and V_max during operation, the distance P_jPN associated with the PN junction being chosen in such a way that;

k₁·

P_fluxE≤

P_jPN≤

k₂·

P_fluxE

k₃·

P_FluxS≤

P_jPN≤

k₄·

hd FluxS

with k₁=0.5 and k₂=2, and with k₃=0.5 and k₄=2, for any value of V between V_min and V_max.

6. The phase modulator according to claim 1, wherein the light flow propagates in a dual-mode manner in the at least one multimode modulation guide according to a fundamental mode and a secondary mode and has a wavelength λ

and a power distribution oscillating according to a period P_flux such that;

P_flux=λ

/(n_eff1−

n_eff2)

where n_eff1 is an effective index associated with a fundamental mode and n_eff2 is an effective index associated with a secondary mode, farther satisfying n_eff1>

n_eff2.

7. The phase modulator according to claim 6, wherein V_min=0 Volts and |V_max|≤

8V.

8. The phase modulator according claim 1, wherein the at least one multimode modulation guide has an input and an output and P_jPN is substantially, preferably strictly, constant along the main axis (y) of propagation between the input and the output of the at least one multimode modulation guide.

9. The phase modulator according to claim 1, wherein the oscillating continuous function, is periodic, with a period P_jPN and wherein the at least one multimode modulation guide has an input and an output and the period P_jPN varies along the main axis (y) of propagation between a period P_jPNE at the input of the at least one multimode modulation guide and a period P_jPNS at the output of the at least one multimode modulation guide, such that;

l₁·

P_jPNS≤

P_jPNE≤

l₂·

P_jPNS

with l₁=0.8 and l₂=1.2.

10. The phase modulator according to claim 1, wherein the phase modulator is configured for a light wave having a wavelength λ

, such that P_jPN≥

λ

.

11. The phase modulator according to claim 1, wherein the at least one multimode modulation guide is a dual-mode guide.

12. The phase modulator according to claim 1, wherein the input guide is a single-node guide having an axis of propagation not aligned with the main axis (y) of propagation of the at least one multimode modulation guide.

13. The phase modulator according to claim 1, wherein the input guide is an output of a mode converter.

14. The phase modulator according to claim 1, wherein the phase modulator is configured for a light wave having a wavelength λ

between 700 nm (10<sup>−

9</sup> metres) and 3000 nm, and preferably 1530 nm≤

λ

≤

1585 nm (“

C”

band) or 1260 nm≤

λ

≤

1360 nm (“

O”

band).

15. The phase modulator according to claim 1, wherein a doping of the P-doped zone [[is less than 10¹⁸ cm⁻

3, preferably approximately 10¹⁷ cm<sup>−

3</sup>.

16. The phase modulator according to claim 1, wherein a doping of the N-doped zone is less than 2.10¹⁸ cm⁻

3, preferably approximately 2.10¹⁷ cm<sup>−

3</sup>.

17. The phase modulator according to claim 1, wherein said oscillating continuous function is sinusoidal.

18. The phase modulator according to claim 1, wherein said oscillating continuous function is triangular.

19. A switch comprising

a phase modulator according to claim 1 and at least two output guides, the output of the at least one multimode modulation guide being optically coupled to inputs of the output guides.

20. An intensity modulator comprising at least:

a phase modulator according to any one of claims 1 and an output guide, the phase modulator further comprising a first guide segment configured to optically couple the output of the input guide to the input of the at least one multimode modulation guide, said first guide segment being further configured to optically couple the output of the at least one multimode modulation guide to an input of the output guide,

a second guide segment extending from the output of the input guide to the input of the output guide.