A device for realizing an optical parametric ring reflector with adjustable reflectivity

Abstract

The present invention discloses a device for realizing an optical parametric reflector with adjustable reflectivity, which is composed of a four-port optical coupler with an arbitrary beam splitting ratio, a first adjustable optical attenuator, a dispersive medium, a nonlinear optical parametric medium, and a second adjustable optical attenuator. The device is characterized in that it can realize perfect separation of parametric light, signal light, and pump light for a four-port beam splitter with an arbitrary beam splitting ratio; the separation degree of parametric light, signal light, and pump light can be arbitrarily adjusted by the first adjustable optical attenuator and the second adjustable optical attenuator. The present invention utilizes two adjustable optical attenuators to realize an optical parametric reflector device with adjustable reflectivity, so that parametric light, signal light, and pump light are perfectly separated, and an entangled light beam with frequency degeneracy and spatial separation is obtained.

Description

Technical Field

[0001] The invention belongs to the field of quantum information process, and in particular relates to a device for realizing an optical parametric ring reflector with adjustable reflectivity. Background Art

[0002] The parametric light wave generated by four-wave mixing and the amplified signal light wave are a pair of twin beams with entanglement characteristics. In particular, the frequency-degenerate parametric light wave and signal light wave can form a nonlinear interferometer based on an optical parametric amplifier and a linear beam splitter, achieving quantum precision measurement that breaks through the classical limit (see the literature J. Kong, ZY Ou, and W. Zhang,"Phase-measurement sensitivity beyond the standard quantum limit in aninterferometer consisting of a parametric amplifier and a beam splitter,"Physical Review A, 2013, 87(2): 023825). Compared with the nonlinear interferometer composed of two non-degenerate optical parametric amplifiers, this interferometer has a simpler structure and consumes less quantum resources. However, unlike non-degenerate twin beams, the degenerate twin beams generated by the four-wave mixing effect in a straight fiber have the same frequency and cannot be spatially separated by a filter.

[0003] Theoretically, a 3dB optical parametric loop mirror can achieve spatial separation of parametric light waves and amplified signal light waves generated by the fiber four-wave mixing process, including spatial separation of parametric light waves and signal light waves with similar or identical frequencies (see K. Mori, T. Morioka, and M. Saruwatari, "Optical parametric loop mirror," Optics Letters, 1995, 20(12): 1424-1426). However, there has been no report on the use of a 3dB optical parametric loop mirror device to produce frequency-degenerate, spatially separated, and entangled twin beams. This is mainly because the standardization of commercial 3dB optical couplers cannot be guaranteed. Therefore, studying the reflectivity of non-3dB optical parametric loop mirrors is expected to achieve the generation of frequency-degenerate twin beams and perfect spatial separation, which is of great significance to frequency-degenerate nonlinear interferometers and quantum precision measurements. Summary of the invention

[0004] The purpose of the present invention is to solve the problem of perfect spatial separation of frequency degenerate twin beams and to provide an optical parametric ring reflector realization device with adjustable reflectivity.

[0005] The solution of the present invention is:

[0006] A reflectivity adjustable optical parametric ring reflector realization device, characterized in that the device is composed of a four-port optical coupler with an arbitrary beam splitting ratio, a first adjustable optical attenuator, a dispersive medium, a nonlinear optical parametric medium, and a second adjustable optical attenuator, and the position relationship is as follows: the c port of the four-port optical coupler with an arbitrary beam splitting ratio is connected to a port of the first adjustable optical attenuator, the other port of the first adjustable optical attenuator is connected to a port of the dispersive medium, the other port of the dispersive medium is connected to a port of the nonlinear optical parametric medium, the other port of the nonlinear optical parametric medium is connected to a port of the second adjustable optical attenuator, and the other port of the second adjustable optical attenuator is connected to a port of the four-port optical coupler with an arbitrary beam splitting ratio, so as to form an optical parametric ring. The first pump, the second pump, and the injection signal are injected from the a port of the four-port optical coupler with an arbitrary beam splitting ratio, and enter the optical parametric ring through the c port and the d port of the four-port optical coupler with an arbitrary beam splitting ratio, and are divided into the first pump, the second pump, and the injection signal propagating in the clockwise direction and the counterclockwise direction. The first pump, the second pump and the injection signal propagating in the clockwise direction sequentially pass through the first adjustable optical attenuator, the dispersion medium and the nonlinear optical parametric medium to generate the parametric light wave propagating in the clockwise direction and the amplified signal light wave; the first pump, the second pump, the parametric light wave and the amplified signal light wave propagating in the clockwise direction pass through the second adjustable optical attenuator and enter the d-port of the four-port optical coupler with any beam splitting ratio. The first pump, the second pump and the injection signal propagating in the counterclockwise direction sequentially pass through the second adjustable optical attenuator and the nonlinear optical parametric medium to generate the parametric light wave propagating in the counterclockwise direction and the amplified signal light wave; the first pump, the second pump, the parametric light wave and the amplified signal light wave propagating in the counterclockwise direction pass through the dispersion medium and the first adjustable optical attenuator and enter the c-port of the four-port optical coupler with any beam splitting ratio. The clockwise and counterclockwise propagating first pump, second pump, parametric light wave and amplified signal light wave interfere in a four-port optical coupler with an arbitrary splitting ratio, and the first pump, second pump, parametric light wave and amplified signal light wave after interference are output from port a and port b of the four-port optical coupler with an arbitrary splitting ratio.

[0007] The beneficial effects of the present invention are:

[0008] 1. The present invention utilizes two optical attenuators with adjustable transmittance to achieve continuous adjustment of the reflectivity of an optical parametric ring reflector formed by an optical coupler with any beam splitting ratio.

[0009] 2. The present invention can achieve perfect separation of frequency-degenerate parametric light waves and amplified signal light waves, and obtain spatially separated frequency-degenerate twin light beams. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of a device for realizing an optical parametric ring reflector with adjustable reflectivity according to the present invention.

[0011] Figure 2 The figure is the numerical simulation result of the normalized parametric light wave power at the output port of the optical parametric ring reflector under different conditions. Figure (a) and Figure (b) show the changes of the normalized parametric light wave power at the output port a and the output port b of the optical parametric ring reflector with the efficiency of the first adjustable optical attenuator when the efficiency of the second adjustable optical attenuator is 1 and the splitting ratio of the optical coupler is different. Figure (c) and Figure (d) show the changes of the normalized parametric light wave power at the output port a and the output port b of the optical parametric ring reflector with the efficiency of the second adjustable optical attenuator when the efficiency of the second adjustable optical attenuator is 1 and the splitting ratio of the optical coupler is different. DETAILED DESCRIPTION

[0012] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0013] Figure 1 The present invention is a schematic diagram of a structure of an embodiment of an optical parametric ring reflector with adjustable reflectivity. This embodiment is applicable to an optical parametric ring reflector with adjustable reflectivity, which is composed of a four-port optical coupler 1 with an arbitrary beam splitting ratio, a first adjustable optical attenuator 2, a dispersive medium 3, a nonlinear optical parametric medium 4, and a second adjustable optical attenuator 5.

[0014] The c-port of the four-port optical coupler 1 with arbitrary splitting ratio is connected to one port of the first adjustable optical attenuator 2, the other port of the first adjustable optical attenuator 2 is connected to one port of the dispersive medium 3, the other port of the dispersive medium 3 is connected to one port of the nonlinear optical parametric medium 4, the other port of the nonlinear optical parametric medium 4 is connected to one port of the second adjustable optical attenuator 5, the other port of the second adjustable optical attenuator 5 is connected to the d-port of the four-port optical coupler 1 with arbitrary splitting ratio, to form an optical parametric loop.

[0015] The first pump, the second pump and the injection signal satisfying the phase matching condition of four-wave mixing are injected from the a port of the four-port optical coupler 1 with arbitrary beam splitting ratio, and enter the optical parametric loop through the c port and the d port of the four-port optical coupler 1 with arbitrary beam splitting ratio, and are divided into the first pump, the second pump and the injection signal propagating in the clockwise direction and the counterclockwise direction. The first pump, the second pump and the injection signal propagating in the clockwise direction successively pass through the first adjustable optical attenuator 2, the dispersion medium 3, and the nonlinear optical parametric medium 4 to generate the parametric light wave propagating in the clockwise direction and the amplified signal light wave; the first pump, the second pump, the parametric light wave and the amplified signal light wave propagating in the clockwise direction pass through the second adjustable optical attenuator 5 and enter the d port of the four-port optical coupler 1 with arbitrary beam splitting ratio. The first pump, the second pump and the injection signal propagating in the counterclockwise direction successively pass through the second adjustable optical attenuator 5 and the nonlinear optical parametric medium 4 to generate a parametric light wave propagating in the counterclockwise direction and an amplified signal light wave; the first pump, the second pump, the parametric light wave and the amplified signal light wave propagating in the counterclockwise direction pass through the dispersion medium 3 and the first adjustable optical attenuator 2 and enter the c port of the four-port optical coupler 1 with an arbitrary beam splitting ratio. The first pump, the second pump, the parametric light wave and the amplified signal light wave propagating in the clockwise and counterclockwise direction interfere in the four-port optical coupler 1 with an arbitrary beam splitting ratio, and the first pump, the second pump, the parametric light wave and the amplified signal light wave after interference are output from the a port and the b port of the four-port optical coupler 1 with an arbitrary beam splitting ratio. The normalized power of the parametric lightwave output from the a port and the b port of the four-port optical coupler 1 with an arbitrary splitting ratio is determined by the first pump, the second pump, the phase difference between the injected signal and the generated parametric lightwave introduced by the dispersive medium 3, the splitting ratio x of the four-port optical coupler 1 with an arbitrary splitting ratio, the efficiency ξ of the first adjustable optical attenuator and the efficiency δ of the second adjustable optical attenuator.

[0016] When the phase difference between the first pump, the second pump, the injection signal and the generated parametric light wave introduced by the dispersive medium 3 is an odd multiple of π, the normalized power of the parametric light wave output from the a port and the b port of the four-port optical coupler 1 with an arbitrary beam splitting ratio varies with the efficiency of the first adjustable optical attenuator as shown in Figure 2 As shown in (a) and (b), the efficiency of the second adjustable optical attenuator changes as Figure 2As shown in (c) and (d). When the splitting ratio x of the four-port optical coupler 1 with an arbitrary splitting ratio is between 0 and 0.5, the efficiency of the first adjustable optical attenuator can be set to 1, and only the efficiency of the second adjustable optical attenuator can be adjusted so that the parametric lightwave is output only from the b-port of the four-port optical coupler 1 with an arbitrary splitting ratio. When the splitting ratio x of the four-port optical coupler 1 with an arbitrary splitting ratio is between 0.5 and 1, the efficiency of the second adjustable optical attenuator can be set to 1, and only the efficiency of the first adjustable optical attenuator can be adjusted so that the parametric lightwave is output only from the b-port of the four-port optical coupler 1 with an arbitrary splitting ratio.

Claims

1. A device for realizing an optical parametric ring reflector with adjustable reflectivity, characterized in that: The device is composed of a four-port optical coupler (1) with an arbitrary beam splitting ratio, a first adjustable optical attenuator (2), a dispersive medium (3), a nonlinear optical parametric medium (4), and a second adjustable optical attenuator (5), wherein the positional relationship is as follows: the c port of the four-port optical coupler (1) with an arbitrary beam splitting ratio is connected to one port of the first adjustable optical attenuator (2), the other port of the first adjustable optical attenuator (2) is connected to one port of the dispersive medium (3), the other port of the dispersive medium (3) is connected to one port of the nonlinear optical parametric medium (4), and the other port of the nonlinear optical parametric medium (4) is connected to one port of the nonlinear optical parametric medium (4). The first pump, the second pump and the injection signal are injected from the a port of the four-port optical coupler (1) with any beam splitting ratio, and enter the optical parametric loop through the c port and the d port of the four-port optical coupler (1) with any beam splitting ratio, and are divided into the first pump, the second pump and the injection signal propagating in the clockwise direction and the counterclockwise direction, respectively. The input signal passes through the first adjustable optical attenuator (2), the dispersion medium (3), and the nonlinear optical parametric medium (4) in sequence to generate a parametric light wave propagating in a clockwise direction and an amplified signal light wave. The first pump, the second pump, the parametric light wave, and the amplified signal light wave propagating in a clockwise direction pass through the second adjustable optical attenuator (5) and enter the d port of the four-port optical coupler (1) with an arbitrary beam splitting ratio. The first pump, the second pump, and the injection signal propagating in a counterclockwise direction pass through the second adjustable optical attenuator (5) and the nonlinear optical parametric medium (4) in sequence to generate a parametric light wave propagating in a counterclockwise direction and an amplified signal light wave. The first pump, the second pump, the parameter light wave and the amplified signal light wave propagating counterclockwise enter the c port of the four-port optical coupler (1) with an arbitrary beam splitting ratio after passing through a dispersion medium (3) and a first adjustable optical attenuator (2); the first pump, the second pump, the parameter light wave and the amplified signal light wave propagating clockwise and counterclockwise interfere with each other in the four-port optical coupler (1) with an arbitrary beam splitting ratio; and the first pump, the second pump, the parameter light wave and the amplified signal light wave after interference are output from the a port and the b port of the four-port optical coupler (1) with an arbitrary beam splitting ratio.

2. A device for realizing an optical parametric ring reflector with adjustable reflectivity applicable to claim 1, characterized in that: The output ratio of the parametric light wave after interference from the b port of the four-port optical coupler (1) with an arbitrary splitting ratio is jointly determined by the splitting ratio of the four-port optical coupler (1) with an arbitrary splitting ratio, the transmittance of the first adjustable optical attenuator (2) and the transmittance of the second adjustable optical attenuator (5).

3. A device for realizing an optical parametric ring reflector with adjustable reflectivity applicable to claim 1, characterized in that: When the splitting ratio of the four-port optical coupler (1) with an arbitrary splitting ratio is greater than 0.5, the transmittance of the second adjustable optical attenuator (5) is set to 1, and only the transmittance of the first adjustable optical attenuator (2) is adjusted so that the parametric light wave after interference is output only from the b port of the four-port optical coupler (1) with an arbitrary splitting ratio.

4. A device for realizing an optical parametric ring reflector with adjustable reflectivity applicable to claim 1, characterized in that: When the splitting ratio of the four-port optical coupler (1) with an arbitrary splitting ratio is less than 0.5, the transmittance of the first adjustable optical attenuator (2) is set to 1, and only the transmittance of the second adjustable optical attenuator (5) is adjusted so that the parametric light wave after interference is output only from the b port of the four-port optical coupler (1) with an arbitrary splitting ratio.

Images