CN208797959U

CN208797959U - Hybrid integrated quantum phase coding and decoding system based on PLC and LiNbO3

Info

Publication number: CN208797959U
Application number: CN201821428446.4U
Authority: CN
Inventors: 付云飞; 黄蕾蕾; 赵义博
Original assignee: Zhejiang Kyushu Quantum Information Technology Ltd By Share Ltd
Current assignee: Zhejiang Kyushu Quantum Information Technology Ltd By Share Ltd
Priority date: 2018-09-03
Filing date: 2018-09-03
Publication date: 2019-04-26
Anticipated expiration: 2028-09-03

Abstract

A kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding system, in LiNbO₃The input terminal of chip, input optical fibre pass through LiNbO₃Waveguide connects three-dB coupler, and the two-way output end of the three-dB coupler passes through LiNbO respectively₃Waveguide connects two-way High speed phase modulators, in LiNbO₃Chip output, two-way High speed phase modulators pass through LiNbO respectively₃Waveguide is correspondingly connected with two-way waveguide coupled zone；In PLC chip input terminal, two-way PLC waveguide passes through two-way waveguide coupled zone and LiNbO respectively₃The two-way LiNbO of chip section₃Waveguide connection；PLC waveguide connects PLC delay line all the way, and another way PLC waveguide connects hot optical phase modulator；PLC delay line and hot optical phase modulator are separately connected two input terminals of directional coupler, and two output ends of directional coupler connect two-way output optical fibre.Compared with prior art, the utility model combination LiNbO₃With the advantage of two kinds of materials of PLC, LiNbO is utilized₃Material makes High speed phase modulators, does low-loss delay using PLC waveguide, and the chip-scale for realizing AMZI is integrated, realizes high-speed phase coding.

Description

Hybrid integrated quantum phase coding and decoding system based on PLC and LiNbO3

Technical field

The utility model relates to quantum phase coding techniques field, in particular to a kind of mixing based on PLC and LiNbO3 Integrated quantum phase coding and decoding system.

Background technique

Quantum information technology originates from the eighties in last century, is broadly divided into quantum communications and the big research side of quantum calculation two To.With being constantly progressive for science and technology, based on the encryption technology of classical information due to the limitation of its bottom basic principle, deposit In intrinsic security risk.Quantum secret communication has unconditional peace physically because of quantum-mechanical philosophy Quan Xing.Therefore, quantum key distribution technology (Quantum Key Distribution, QKD) using more and more extensive.

The premise of quantum key distribution technology is to prepare quantum bit.The space encoder that one quantum bit utilizes is 2 dimensions Hilbert space, common coding mode mainly have polarization encoder and phase code.Existing frequently-used phase code Quantum key distribution scheme mostly uses traditional discrete optical component to build by technologies such as fused fiber splices, traditional Phase code QKD system is as shown in Figure 1.Wherein, phase code and phase decoding device are unequal arm Mach-Zehnder interferometer (AMZI), it is made of three-dB coupler, phase-modulator, fiber delay line etc., the encoder of transmitting terminal (Alice) and receiving end (Bob) decoder requirements have equal arm length difference.Because the consistency of the AMZI arm length difference of transmitting terminal and receiving end is direct Influence QKD system at code rate.In order to guarantee QKD at code rate, in actual production, the technique for usually requiring that fiber cut It is even lower that precision reaches hundred micron orders, this point often it is difficult to ensure that.This is to restrict phase code QKD functionization and commercialization Key difficulties.

In order to solve this problem, as shown in Figure 1, the units such as Japan NEC propose the horse using PLC waveguide production unequal arm Conspicuous Zehnder interferometer.But the unequal arm Mach-Zehnder interferometer of PLC waveguide production, it cannot achieve the phase-modulation of high speed.

Utility model content

The utility model aim is to provide a kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding System, with solve conventional phase coding QKD system in unequal arm MZI interferometer process consistency it is poor, cause QKD system at code rate Low technical problem.

The technical solution of the utility model is achieved in that

A kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding system, including it is sequentially connected defeated Enter optical fiber, LiNbO₃Chip, PLC chip and output optical fibre, the LiNbO₃Chip includes LiNbO₃Waveguide, three-dB coupler and two Road High speed phase modulators, in LiNbO₃The input terminal of chip, input optical fibre pass through LiNbO₃Waveguide connects three-dB coupler, described The two-way output end of three-dB coupler passes through LiNbO respectively₃Waveguide connects two-way High speed phase modulators, in LiNbO₃Chip output End, two-way High speed phase modulators pass through LiNbO respectively₃Waveguide is correspondingly connected with first wave guide coupled zone, second waveguide coupled zone, The first wave guide coupled zone, second waveguide coupled zone are connect with PLC chip；

The PLC chip includes PLC waveguide, PLC delay line, directional coupler；In PLC chip input terminal, two-way PLC wave It leads respectively through first wave guide coupled zone, second waveguide coupled zone and LiNbO₃The two-way LiNbO of chip section₃Waveguide connection；All the way PLC waveguide connects PLC delay line, and another way PLC waveguide connects hot optical phase modulator；PLC delay line and hot optical phase modulator connect respectively Two input terminals of directional coupler are connect, two output ends of directional coupler connect two-way output optical fibre.

Preferably, the three-dB coupler is Y type optical power score device, 2x2 directional coupler, appointing in multi-mode interferometer It is a kind of.

Preferably, the LiNbO₃Waveguide spreads manufacturing process using proton exchange, titanium.

Preferably, the refringence of the PLC waveguide is 0.5%-2%.

Preferably, the LiNbO₃The polishing angle of chip input and output side is 10-15 °.

Preferably, the polishing angle of the PLC chip input terminal is 8-15 °, and the polishing angle of output end is 8 °.

Preferably, the manufacturing process of the PLC waveguide is that material is deposited on silicon base chip using chemical vapour deposition technique On, recycle ultraviolet photolithographic technique to form the mask pattern of delay waveguide, it finally will using inductively coupled plasma etching technique Mask pattern, which is transferred on the material of deposition, forms PLC waveguide.

Compared with prior art, the utility model have it is following the utility model has the advantages that

1, the utility model proposes it is a kind of based on PLC and LiNbO3 hybrid integrated quantum phase coding with decoding be System, combines the advantage of two kinds of materials of LiNbO3 and PLC, makes High speed phase modulators using LiNbO3 material, utilizes PLC wave It leads and does low-loss delay, the chip-scale for realizing AMZI is integrated, and small, phase code rate is high, device cost is low, ruler with being lost It is very little small, the advantages that can be mass produced.

2, a kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 provided by the utility model is with decoding System, ensure that the consistency of AMZI arm length difference using semiconductor technology, solve conventional phase coding QKD system fiber cut essence The problem of degree is difficult to ensure.

3, a kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 provided by the utility model is with decoding System, coding and decoding AMZI there are two high speed phase converter, can combine realization 0 by way of digital modulation, pi/2, π, 3 Pi/2,4 kinds of phase codes, realizes the phase code of high speed.

4, a kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 of the utility model and decoding system, by Very small (about 0.1dB) is lost in PLC delay waveguide transmission, as the loss of the two-arm of AMZI, does not need to increase additional device Part or technique adjust the light power equalization of two-arm, meanwhile, Ke Yishi smaller compared with legacy system in the Insertion Loss of receiving terminal (Bob) Now bigger transmission range；

5, a kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 provided by the utility model is with decoding System, coding chip is identical with the structure of decoding chip, may be implemented the uniformity of device, save research and development and manufacture at This.

Detailed description of the invention

Fig. 1 is phase code QKD system schematic diagram in the prior art；

Fig. 2 is a kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 of the utility model and decoding system Schematic illustration.

In figure: 10- single-photon source, 11-3dB coupler, 12- optical fiber, 13- fiber delay line, 14- phase-modulator, 15- Three-dB coupler, 16- fiber channel, 17-3dB coupler, 18- optical fiber, 19- fiber delay line, 110- phase-modulator, 111- Three-dB coupler, 112- single-photon detector, 113- single-photon detector, 21- input optical fibre, 22-LiNbO₃Waveguide, 23-3dB Coupler, 24- the first high speed phase converter, 25- the second high speed phase converter, 26-LiNbO₃Chip, 27- first wave guide coupled zone, 28- second waveguide coupled zone, the hot optical phase modulator of 29-, 210-PLC delay line, 211-PLC waveguide, 212- directional coupler, 213- PLC chip, 214- output optical fibre.

Specific embodiment

The following will be combined with the drawings in the embodiments of the present invention, is clearly and completely described the utility model.

As shown in Fig. 2, a kind of hybrid integrated quantum phase coding and decoding based on PLC and LiNbO3 of the utility model System, including sequentially connected input optical fibre 21, LiNbO₃Chip 26, PLC chip 213 and output optical fibre 214, the output Optical fiber 214 includes two-way, the LiNbO₃Chip 26 includes LiNbO₃Waveguide 22, three-dB coupler 23 and two-way high-speed phase tune Device processed, the two-way are the first High speed phase modulators 24 and the second High speed phase modulators 25；In LiNbO₃26 input terminal of chip, First High speed phase modulators 24 and the second High speed phase modulators 25 pass through LiNbO respectively₃Waveguide 22 is correspondingly connected with first wave Lead coupled zone 27, second waveguide coupled zone 28, the first wave guide coupled zone 27, second waveguide coupled zone 28 are and PLC chip 213 connections；

The PLC chip 213 includes PLC waveguide 211, PLC delay line 210, directional coupler 212；In PLC chip 213 Input terminal, two-way PLC waveguide 211 pass through first wave guide coupled zone 27, second waveguide coupled zone 28 and LiNbO respectively₃Chip 26 The two-way LiNbO of section₃Waveguide 22 connects；PLC waveguide 211 connects PLC delay line 210 all the way, and another way PLC waveguide 211 connects Hot optical phase modulator 29；PLC delay line 210 and hot optical phase modulator 29 are separately connected two input terminals of directional coupler 212, orientation Two output ends of coupler 212 connect two-way output optical fibre 214.

LiNbO₃Chip 26, PLC chip 213 are connected by waveguide coupled zone, by LiNbO inside the waveguide coupled zone₃ Waveguide 22 is coupled and aligned with PLC waveguide 211 by high-precision Alignment Process.

The input optical fibre 21, effect is that quantum optical signal is coupled to PLC and LiNbO₃Hybrid integrated type amount Sub- phase code or decoding chip.

The LiNbO₃Chip 26 and the PLC chip 213, forming has high-speed phase coding or decoding function AMZI, when coding, make AMZI two-arm realize 0, pi/2, π, a certain given reference phase difference in 3 pi/2s, and when decoding realizes 0, in pi/2 A certain given reference phase difference.

The two-way output optical fibre 214, when executing encoding function as chip, certain of output optical fibre 214 connects all the way It is connected to fiber channel；When executing decoding function as chip, two-way output optical fibre 214 is separately connected two single photon detections Device.

The three-dB coupler 23 is designed to Y type optical power beam splitter, input light is divided into the light of two beam same intensities And it is respectively coupled to the first High speed phase modulators 24 and the second High speed phase modulators 25.

First High speed phase modulators 24 and the second High speed phase modulators 25 realize 0, pi/2 and 0, π phase respectively Position modulation.This implementation can reduce requirement of the high speed phase converter to driving voltage.

LiNbO is realized in the first wave guide coupled zone 27, second waveguide coupled zone 28₃Chip 26 and PLC chip 213 Optical coupled connection.

The PLC delay line 210, realizes the delay of light pulse signal.

The hot optical phase modulator 29 realizes the initial phase biasing and feedback regulation of AMZI.

The directional coupler 212 realizes the conjunction beam of the two-arm of AMZI.

The LiNbO₃The polishing angle of 26 input and output side of chip is 10 °.

The polishing angle of 213 input terminal of PLC chip is 15 °, and the polishing angle of output end is 8 °.

The LiNbO₃The manufacturing process of waveguide 22 is proton exchange.

The refringence of the PLC waveguide 211 is 0.75%.

PLC and LiNbO₃Hybrid integrated type quantum phase coding chip the course of work are as follows: single-photon source generate light Subsignal is coupled to phase code chip by input optical fibre 21, adjusts hot optical phase modulator for the initial phase difference of AMZI and is modulated to π Phase, it is poor using 4 kinds of outs of phase of the first High speed phase modulators 24 and the load of 25 combining random of the second High speed phase modulators (0, pi/2, π, 3 pi/2s) realizes 4 kinds of different phase states of output, and is output to light by any road of output optical fibre 214 or 215 Fine channel.Wherein 0, π is one group of orthogonal basis, and pi/2,3 pi/2s are another group of orthogonal basis.Phase code process is as shown in table 1.

PLC and LiNbO₃Hybrid integrated type quantum phase decoding chip the course of work are as follows: the photon in fiber channel Signal is coupled to phase decoding chip by input optical fibre 21, adjusts hot optical phase modulator for the initial phase difference of AMZI and is modulated to 0 phase Position, the 2 kinds of differences of some random loading combined using the first High speed phase modulators 24 with the second High speed phase modulators 25 Phase difference (0, pi/2) realizes 2 kinds of different measurement base phase states.Decoded optical signal is exported by two-way output optical fibre 214 It is coupled to two single-photon detectors.Phase decoding process is as shown in table 2.

1 phase code example of table

2 phase decoding example of table

The structure of comprehensive the utility model is with principle it is found that the hybrid integrated based on PLC and LiNbO3 of the utility model Quantum phase coding and decoding system, in conjunction with LiNbO₃With the advantage of two kinds of materials of PLC, LiNbO is utilized₃Material makes high speed phase Position modulator, does low-loss delay using PLC waveguide, and the chip-scale for realizing AMZI is integrated, realizes high-speed phase coding.

Claims

1. a kind of hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding system, including sequentially connected input Optical fiber, LiNbO₃Chip, PLC chip and output optical fibre, which is characterized in that the LiNbO₃Chip includes LiNbO₃Waveguide, 3dB Coupler and two-way High speed phase modulators, in LiNbO₃The input terminal of chip, input optical fibre pass through LiNbO₃Waveguide connects 3dB The two-way output end of coupler, the three-dB coupler passes through LiNbO respectively₃Waveguide connects two-way High speed phase modulators, LiNbO₃Chip output, two-way High speed phase modulators pass through LiNbO respectively₃Waveguide is correspondingly connected with first wave guide coupled zone, Two waveguide coupled zones, the first wave guide coupled zone, second waveguide coupled zone are connect with PLC chip；

The PLC chip includes PLC waveguide, PLC delay line, directional coupler；In PLC chip input terminal, two-way PLC waveguide point It Tong Guo not first wave guide coupled zone, second waveguide coupled zone and LiNbO₃The two-way LiNbO of chip section₃Waveguide connection；PLC all the way Waveguide connects PLC delay line, and another way PLC waveguide connects hot optical phase modulator；PLC delay line and hot optical phase modulator are separately connected fixed To two input terminals of coupler, two output ends of directional coupler connect two-way output optical fibre.

2. the hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding system, feature exist as described in claim 1 In the three-dB coupler is any one of Y type optical power score device, 2x2 directional coupler, multi-mode interferometer.

3. the hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding system, feature exist as described in claim 1 In the refringence of the PLC waveguide is 0.5%-2%.

4. the hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding system, feature exist as described in claim 1 In the LiNbO₃The polishing angle of chip input and output side is 10-15 °.

5. the hybrid integrated quantum phase coding based on PLC and LiNbO3 and decoding system, feature exist as described in claim 1 In the polishing angle of the PLC chip input terminal is 8-15 °, and the polishing angle of output end is 8 °.