阅读说明：本技术 光延迟方法和系统 (Optical delay method and system ) 是由 A·梅洛尼 D·梅拉蒂 于 2018-05-15 设计创作，主要内容包括：一种光延迟方法及相关系统,包括：-沿光延迟设备(10)传播光信号,该光延迟设备(10)包括：具有可变输入耦合器(20)和延迟元件的第一级(11)、具有可变中间耦合器(30)和延迟元件的中间级(12)、包括可变输出耦合器(40)的输出级(13)；-将输入耦合器(20)和输出耦合器(40)的耦合比设为等于在至少三个值中选择的值K1,-将中间耦合器(30)的耦合比设为等于值K2,其中K1＝sin<Sup>2</Sup>(θ)而K2＝sin<Sup>2</Sup>(A*θ),其中θ大于或等于零且小于或等于π/2,并且A大于或等于1.5且小于或等于2.5。(An optical delay method and related system, comprising: -propagating an optical signal along an optical delay device (10), the optical delay device (10) comprising: a first stage (11) with a variable input coupler (20) and a delay element, an intermediate stage (12) with a variable intermediate coupler (30) and a delay element, an output stage (13) comprising a variable output coupler (40); -setting the coupling ratio of the input coupler (20) and the output coupler (40) equal to a value K1 selected among at least three values, -setting the coupling ratio of the intermediate coupler (30) equal to a value K2, where K1 is sin 2 (theta) and K2 ═ sin 2 (A θ), where θ is greater than or equal toIs zero and less than or equal to pi/2, and A is greater than or equal to 1.5 and less than or equal to 2.5.)

1. An optical delay method comprising:

-providing an optical delay device (10), the optical delay device (10) comprising:

-a first stage (11) comprising a variable input coupler (20), the variable input coupler (20) having a first input port (21), and first and second output ports (22, 23), and first and second optical paths (24, 25) optically connected to the first and second output ports (22, 23), respectively, wherein an optical path difference between the first and second optical paths (24, 25) is greater than zero;

-an intermediate stage (12), the intermediate stage (12) comprising:

-a variable intermediate coupler (30) having a first input port (31) and a second input port (32), and a first output port (33) and a second output port (34), wherein the first input port (31) and the second input port (32) of the intermediate coupler (30) are optically connected to the first optical path (24) and the second optical path (25) downstream of the first optical path (24) and the second optical path (25), respectively;

-a third optical path (35) and a fourth optical path (36) optically connected to the first output port (33) and the second output port (34) of the intermediate coupler, respectively, downstream of the intermediate coupler (30), wherein an optical path difference between the third optical path (35) and the fourth optical path (36) is greater than zero;

-an output stage (13) comprising a variable output coupler (40), the variable output coupler (40) having a first input port (41) and a second input port (42), and a first output port (43), wherein the first input port (41) and the second input port (42) of the output coupler are optically connected to the third optical path and the fourth optical path, respectively, downstream of the third optical path (35) and the fourth optical path (36);

-selecting a value K1 among a plurality of values comprising a minimum value greater than or equal to zero, a maximum value less than or equal to 1, and at least one value comprised between said minimum value and said maximum value, wherein K1 ═ sin²(θ), wherein θ is greater than or equal to zero and less than or equal to π/2;

-setting the coupling ratio of the input coupler (20) and the output coupler (40) equal to the selected value K1,

-setting the coupling ratio of the intermediate coupler (30) equal to a value K2, wherein

K2＝sin²(A*θ)

Wherein A is greater than or equal to 1.5 and less than or equal to 2.5;

-introducing a first optical signal into the first input port (21) of the input coupler (20);

-delaying the first optical signal by an optical delay by propagating the first optical signal along the optical delay device (10);

-picking up the delayed first optical signal from the first output port (32) of the output coupler (40).

2. The method of claim 1, comprising preparing a second optical signal and delaying the first optical signal relative to the second optical signal.

3. The method of claim 1 or 2, wherein the plurality of values of the coupling ratio are consecutively spaced values, wherein a difference between the minimum value and the maximum value of the coupling ratio of each coupler is greater than or equal to 0.4, and wherein the minimum value is less than or equal to 0.4, and/or the maximum value is greater than or equal to 0.6.

4. The method according to any of the preceding claims, wherein a is greater than or equal to 1.7, preferably greater than or equal to 1.9, and/or less than or equal to 2.3, preferably less than or equal to 2.1.

5. The method according to any of the preceding claims, wherein each of the input coupler (20), the intermediate coupler (30) and the output coupler (40) comprises a respective first coupler (26) and second coupler (27), each having a respective coupling ratio equal to 0.5, and a pair of optical paths (28, 29) with equal optical length connecting the first coupler (26) and the second coupler (27).

6. The method according to any one of the preceding claims, wherein the device (10) comprises one or more further intermediate stages (12') optically interposed between the intermediate stage (12) and the output stage (13), each further intermediate stage (12') comprising:

-a further intermediate coupler (30') having a first and a second input port and a first and a second output port, wherein the first and second input ports of the further intermediate coupler are optically connected downstream to the first and second optical paths (35, 36) of the intermediate stage (12) or an immediately preceding further intermediate stage (12'), respectively; and

-further third and further fourth optical paths (35', 36') optically connected downstream to the first and second output ports of the further intermediate coupler (30'), respectively, wherein an optical path difference between the further third and fourth optical paths (35', 36') is larger than zero,

wherein the first input port (41) and the second input port (42) of the output coupler (40) are optically connected to the further third optical path (35') and the further fourth optical path (36') of the immediately preceding further intermediate stage (12'), respectively,

wherein the method further comprises setting the coupling ratio of each other intermediate coupler (30') equal to the value K2.

7. An optical delay system (1) comprising:

-an optical delay device (10), the optical delay device (10) comprising:

-a first stage (11) comprising a variable input coupler (20), the variable input coupler (20) having a first input port (21), and first and second output ports (22, 23), and first and second optical paths (24, 25) optically connected to the first and second output ports (22, 23), respectively, wherein an optical path difference between the first and second optical paths (24, 25) is greater than zero;

-an intermediate stage (12), the intermediate stage (12) comprising:

-a variable intermediate coupler (30), the variable intermediate coupler (30) having a first input port (31) and a second input port (32), and a first output port (33) and a second output port (34), wherein the first input port (31) and the second input port (32) of the intermediate coupler (30) are optically connected to the first optical path (24) and the second optical path (25) downstream of the first optical path (24) and the second optical path (25), respectively; and

-a third optical path (35) and a fourth optical path (36) optically connected to the first output port (33) and the second output port (34) of the intermediate coupler, respectively, downstream of the intermediate coupler (30), wherein an optical path difference between the third optical path (35) and the fourth optical path (36) is greater than zero;

-an output stage (13) comprising an output coupler (40), the output coupler (40) having a first input port (41) and a second input port (42), and a first output port (43), wherein the first input port (41) and the second input port (42) of the output coupler (40) are optically connected to the third optical path and the fourth optical path, respectively, downstream of the third optical path (35) and the fourth optical path (36); and

-a first actuator (45), a second actuator (46) and a third actuator (47) configured to vary the coupling ratio of the input coupler (20), the intermediate coupler (30) and the output coupler (40) between a minimum value greater than or equal to zero to a maximum value less than or equal to one, respectively; and

-a command and control unit (100) configured to send a first command signal to the first actuator (45) and to the third actuator (47) to set the coupling ratio of the input coupler (20) and of the output coupler (40) to a value K1 selected among a plurality of values comprising the minimum value and the maximum value, and at least one value comprised between the minimum value and the maximum value, and to send a second command signal to the second actuator (46) to set the coupling ratio of the intermediate coupler (30) equal to a value K2, wherein

K1＝sin²(theta) and K2 ═ sin²(A*θ)

Wherein θ is greater than or equal to zero and less than or equal to π/2, and A is greater than or equal to 1.5 and less than or equal to 2.5.

8. The system of claim 7, wherein the first actuator (45), the second actuator (46), and the third actuator (47) are configured to continuously vary the respective coupling ratios.

9. The system of claim 7 or 8, wherein each of the input coupler (20), the intermediate coupler (30) and the output coupler (40) comprises a respective first coupler (26) and second coupler (27) each having a respective coupling ratio equal to 0.5, and a pair of optical paths (28, 29) with equal optical length connecting the first coupler (26) and the second coupler (27), wherein each respective actuator (45, 46, 47) is configured to operate on one of the optical paths (28, 29) in a manner that introduces an optical phase difference 2 Θ between the optical paths of the couplers, wherein Θ is greater than or equal to zero and less than or equal to π/2.

10. The system according to any one of claims 7 to 9, wherein the device (10) comprises one or more further intermediate stages (12') optically interposed between the intermediate stage (12) and the output stage (13), each further intermediate stage (12') comprising:

-a further intermediate coupler (30') having a first and a second input port and a first and a second output port, wherein the first and second input ports of the further intermediate coupler are optically connected downstream to the first and second optical paths (35, 36) of the intermediate stage (12) or an immediately preceding further intermediate stage (12'), respectively;

-a further second actuator (46') configured to vary the coupling ratio of the further intermediate coupler (30') between a minimum value greater than or equal to zero to a maximum value less than or equal to one; and

-further third and further fourth optical paths (35', 36') optically connected downstream to the first and second output ports of the further intermediate coupler (30'), respectively, wherein an optical path difference between the further third and fourth optical paths (35', 36') is larger than zero,

wherein the first input port (41) and the second input port (42) of the output coupler (40) are optically connected to the further third optical path (35') and the further fourth optical path (36') of the immediately preceding further intermediate stage (12'), respectively, and

wherein the command and control unit (100) is configured to send said second command signal to each of said other second actuators (46') to set the coupling ratio of the respective other intermediate couplers (30') equal to said value K2.