Multiple resonator and variable-wavelength light source using the same

• US 20060153267A1
• Filed: 12/28/2005
• Published: 07/13/2006
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yamazaki, Hiroyuki, Suzuki, Kouichi
• Granted Patent: US 7,389,028 B2
• Time in Patent Office: Days
• US Class Current: 372/92
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: H01S 3/0637 Integrated lateral waveguide, e.g. the active waveguide is integrated on a substrate made by Si on insulator technology (Si/SiO2)
• CPC Class Codes: H01S 5/1032 Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region
• CPC Class Codes: H01S 5/142 which comprises an additional resonator

Abstract

An external resonator which includes a multiple resonator with parameters which allow stable wavelength control, and a variable-wavelength light source includes such an external resonator are provided. The external resonator is a multiple resonator which is made up of first to third ring-shaped resonators, each having different light path length, and connected in series via optical coupling means. The parameters of the multiple resonator are characterized in that all the following Expressions <1>, <2> and <3> hold:
L1={M1/(M1−1)}L0   <1>
L2={M2/(M2−1)}L0   <2>
M2−1=(M1−1)²   <3>
where L0 is the light path length of the first resonator, L1 is the light path length of the second resonator and L2 is the light path length of the third resonator, and M1 and M2 are integers of 3 or greater.

Claims

1. A multiple resonator comprising first to third resonators, each having different light path length, connected via optical coupling means, wherein all the following Expressions <

1>

, <

2> and

<

3>

hold;

L1={M1/(M1−

1)}L0  

 

<

1>


L2={M2/(M2−

1)}L0  

 

<

2>


M2−

1=(M1−

1)²  

 

<

3>

where L0 is a light path length of said first resonator, L1 is a light path length of said second resonator and L2 is a light path length of said third resonator, and M1 and M2 are integers of 3 or greater.

2. The multiple resonator according to claim 1, wherein the following Expression <

4>

is used instead of said Expression <

3>

;

√

(M2×

0.7−

1)/1.3<

M1−

1<

√

(M2×

1.3−

1)/0.7  

 

<

4>

3. The multiple resonator according to claim 1, wherein said first to third resonators are first to third ring resonators made up of ring-shaped waveguides each having different light path length.

4. The multiple resonator according to claim 3, further comprising:

a first waveguide, one end of which is connected to one of said first to third ring resonators via optical coupling means; and

a second waveguide, one end of which is connected to another of said first to third ring resonators via optical coupling means.

5. The multiple resonator according to claim 4, wherein the ring-shaped waveguides of said first to third ring resonators and said first and second waveguides are formed as one piece on a quartz-glass-based substrate.

6. The multiple resonator according to claim 4, further comprising variable-wavelength means for changing the resonance wavelength of said multiple resonator.

7. The multiple resonator according to claim 6, wherein said variable-wavelength means is a film-like heater.

8. The multiple resonator according to claim 6, wherein an asymmetric Mach-Zehnder interferometer is inserted in said first waveguide or said second waveguide.

9. A variable-wavelength light source comprising:

a multiple resonator comprising first to third ring resonators made up of ring-shaped waveguides, each having different light path length, connected via optical coupling means, wherein all the following Expressions <

1>

, <

2> and

<

3>

hold;

L1={M1/(M1−

1)}L0  

 

<

1>


L2={M2/(M2−

1)}L0  

 

<

2>


M2−

1=(M1−

1)²  

 

<

3>

,

where L0 is a light path length of said first resonator, L1 is a light path length of said second resonator and L2 is a light path length of said third resonator and M1 and M2 are integers of 3 or greater;

a substrate on which an input/output side waveguide, one end of which is connected to one of said first to third ring resonators via optical coupling means and a reflection side waveguide, one end of which is connected to another of said first to third ring resonators via optical coupling means are formed;

a light reflector provided at the other end of said reflection side waveguide of said substrate;

a light input/output unit, a light input/output end of which is connected to the other end of said input/output side waveguide of said substrate via a non-reflective film; and

a variable-wavelength unit which changes a resonance wavelength of said multiple resonator.

10. The variable-wavelength light source according to claim 9, wherein said light input/output unit is a semiconductor optical amplifier or optical fiber amplifier.

11. The variable-wavelength light source according to claim 9, wherein said variable-wavelength unit is a film-like heater provided on said substrate.

12. The variable-wavelength light source according to claim 11, wherein an asymmetric Mach-Zehnder interferometer is inserted in said input/output side wave guide or said reflection side waveguide.