CN103576399B - A kind of liquid crystal optical phased array antenna implementation method - Google Patents

Abstract

The present invention discloses a kind of liquid crystal optical phased array antenna implementation method, and described liquid crystal optical phased array antenna comprises common electrical pole and grating electrode, and described public electrode is designed to high resistance liquid crystal wedge electrode; Design two electrodes at high resistance liquid crystal wedge electrode two ends, load the voltage with different magnitude of voltage respectively, produce a ramp phase distribution, the equivalent liquid crystal prism adjustable in a hill slope, it is possible to incident wave beam is deflected control continuously; Meanwhile, grating electrode loads quantification voltage, it is possible to realize the stepping deflection control of incident wave beam.

Description

A kind of liquid crystal optical phased array antenna implementation method

Technical field

The present invention relates to a kind of liquid crystal optical phased array antenna implementation method, belong to the technical field such as satellite laser communications and lidar.

Background technology

Laser communication technology in recent years is rapidly developed. Along with the development of satellite laser communications technology, it is necessary to set up satellite laser communications network, it is achieved the communication between satellite and multi-satellite, i.e. a multiple access technology. The laser communications system of research both at home and abroad is point-to-point strand circuit-switched data transmission system at present, adopts mechanical type to catch with mechanism and traditional type acquisition and tracking strategy. Owing to satellite laser communications link range is far away, Laser emission power limited, it is necessary to laser divergence angle is as far as possible close to diffraction limit. The restriction of Stimulated Light beam divergence angle, mechanical scan mechanism can only realize point-to-point laser communication, if to be realized laser multiple spot communication, a platform needs carry multiple optics antenna, it is difficult to meet satellite platform to the requirement of volume, weight and power consumption. This needs to adopt novel optical phased array antenna, it is achieved satellite optical communication multiple access technology.

Owing to satellite laser communications system beam divergence angle is narrow, in order to ensure between star, the robustness of satellite-ground laser communication system, ensure the performance of laser communications system, it is desired to the wave beam control accuracy of novel liquid crystal optical phased array antenna is higher. As shown in Figure 1, the core devices of existing liquid crystal optical phased array antenna is liquid crystal cell, by changing the specific refractory power of liquid crystal cell, thus changes incoming beam wavefront, it is achieved the deflection control of incoming beam. The liquid crystal optical phased array antenna of current foreign study mainly adopts periodic and the design of aperiodicity grating two type, its two lateral electrode is respectively public electrode and grating electrode, owing to grating electrode is discrete electrode, the deflection of its light beam has discontinuity, scanning area can not be carried out effective continuous sweep.

Summary of the invention

Technical problem to be solved by this invention is: for the quasi-continuous deflection control development demand of liquid crystal optical phased array wave beam discontinuous scanning technique feature and light beam, provide a kind of liquid crystal optical phased array antenna implementation method, solve that satellite optical communication is quasi-continuous to wave beam, high precision deflection demand for control, ensure that the performance of satellite laser communications system.

The technical scheme of the present invention is: a kind of liquid crystal optical phased array antenna implementation method, and described liquid crystal optical phased array antenna comprises common electrical pole and grating electrode, and described public electrode is designed to high resistance liquid crystal wedge electrode; Design two electrodes at high resistance liquid crystal wedge electrode two ends, load the voltage with different magnitude of voltage respectively, produce a ramp phase distribution, the equivalent liquid crystal prism adjustable in a hill slope, it is possible to incident wave beam is deflected control continuously; Grating electrode loads and quantizes voltage, it is possible to realize the stepping deflection control of incident wave beam.

The present invention's advantage compared with prior art is:

The liquid crystal optical phased array antenna implementation method of the present invention mainly adopts the wave beam of liquid crystal wedge to deflect control techniques and liquid crystal optical phased array control electrode designing technique continuously, public for the low resistance of available liquid crystal optical phased array electrode is designed to high resistance electrode, forms liquid crystal wedge electrode. Loading Control voltage while of on liquid crystal optical phased array grating electrode and wedge electrode, the continuous deflection control of liquid crystal wedge electrode voltage supplements mutually with the stepping deflection control of liquid crystal grating electrode voltage, it is possible to the quasi-continuous deflection control of the incident wave beam of realization. Solve that satellite optical communication is quasi-continuous to wave beam, high precision deflection demand for control, ensure that the performance of satellite laser communications system.

Accompanying drawing explanation

Fig. 1 liquid crystal optical phased array wave beam deflection schematic diagram

Fig. 2 is the liquid crystal optical phased array antenna structure view of the present invention;

Fig. 3 is simulation results (deflection angle is 1.2 degree).

Embodiment

As shown in Figure 2, the liquid crystal optical phased array antenna of the present invention comprises glass substrate 21 and 27, liquid crystal 24, oriented layer 23 and 25, public electrode 26, and grating electrode 22. Liquid crystal optical phased array antenna adopts the mode of phase-only modulation to realize the effect being similar to transmission blazed grating, and the very big degree of the serviceability of liquid crystal blazed grating is determined by the controllability of parallel pole. In liquid crystal blazed grating periodic unit, the total width equivalence of many electrodes is in grating constant, grating constant is changed by changing the number of electrodes of grating electrode 22, realize the change of angle of diffraction, then by the voltage's distribiuting in regulating cycle unit, the light of certain one-level time is glittered. Blazed grating diffraction angle is determined by grating equation dsin ��=m ��. Wherein d is grating constant, d=N d '. D ' is the electrode cycle, and N is the number of electrode in a grating unit, and driving circuit can produce different magnitudes of voltage and be carried on electrode, makes liquid crystal molecule produce the different quantity of deflecting voltage value and the maximum value of N; �� is blaze angle, and m is level time of glittering, and �� is the wavelength of incident light. The number N changing electrode in a grating unit can change grating constant, and glittering for the m level of wavelength X incident light to change its blaze angle ��, realizes scanning without inertia light beam with this.

Public for the low resistance of liquid crystal optical phased array antenna electrode 26 is designed to high resistance liquid crystal wedge electrode by the present invention; The impedance of high resistance liquid crystal wedge electrode is greater than 1000 ��; Designing two electrodes at the two ends of high resistance liquid crystal wedge electrode, the voltage that two electrodes load different magnitude of voltage respectively produces a ramp phase distribution, and wave beam, in the adjustable liquid crystal prism of a hill slope, is deflected control by equivalence continuously. As shown in Figure 2, applying grating electrode voltage Vi at grating electrode 22, two electrodes at high resistance liquid crystal wedge electrode apply voltage Vcom1, Vcom2 respectively. By loading grating electrode voltage Vi, it is achieved the deflection control of liquid crystal optical phased array stepping wave beam; By changing (Vcom2-Vcom1) relative value, change beam deflection angle degree, it is possible to realize the continuous deflection control of incident wave beam.

If the beam deflection angle degree of liquid crystal optical phased array antenna is ��_s, so ��_sBy liquid crystal grating beam deflection angle degree ��_OPAWith liquid crystal wedge wave beam deflection angle theta_wedgeComposition, that is:

��_s=��_OPA+��_wedge(1)

Assuming that grating electrode not making alive, namely grating electrode does not work, and the beam deflection angle degree of liquid crystal optical phased array is by the control of liquid crystal wedge electrode, and the beam deflection angle degree of liquid crystal wedge meets

${\mathrm{\θ}}_{\mathrm{wedge}}=\frac{\mathrm{\Δ}{\mathrm{\φ}}_{\mathrm{wedge}}}{\mathrm{kL}}---\left(2\right)$

Wherein, k is vacuum wave number, and L is the length of liquid crystal optical phased array antenna, �� ��_wedgeIt it is the phase differential that the different pressure drop in two ends that wedge electrode voltage Vcom1 with Vcom2 is formed produces.

Assuming that high resistance liquid crystal wedge electrode not making alive, namely high resistance liquid crystal wedge electrode does not work, and the beam deflection angle degree of liquid crystal optical phased array is controlled by liquid crystal grating electrode, and liquid crystal grating beam deflection angle degree meets

$\sin {\mathrm{\θ}}_{\mathrm{OPA}}=\frac{\mathrm{\Δ}{\mathrm{\φ}}_{\mathrm{OPA}}}{\mathrm{kd}}---\left(3\right)$

Wherein d is grating constant, �� ��_OPAIt it is the phase transition amount of adjacent equivalence electrode.

Assuming that liquid crystal wedge electrode and liquid crystal grating electrode making alive simultaneously, liquid crystal optical phased array theThe phase-delay quantity �� of root electrode position_iShould be liquid crystal wedge and liquid crystal grating two portions phase-delay quantity sum, represent and be

��_i=��_OPA(i)+��_wedge(i)

Given beam deflection angle degree is ��_s, first deflection precision and deflection scope according to liquid crystal wedge and liquid crystal grating determines ��_OPAAnd ��_wedge, and calculate �� according to formula (2) and formula (3)_OPAAnd ��_wedgePhase-delay quantity �� �� corresponding respectively_OPAWith �� ��_wedge. For liquid crystal wedge, �� ��_wedge=kL��_wedge, phase place increases �� �� from 2 ��_wedge. According to U-Phi(voltage-phase place) relation curve, obtain wedge electrode voltage Vcom2 and Vcom1, then calculate the wedge voltage Vcomi that liquid crystal optical phased array i-th grating electrode pair is answered

$\mathrm{Vcomi}=\mathrm{Vcom}1+\frac{i}{N}\·(\mathrm{Vcom}2-\mathrm{Vcom}1)---\left(4\right)$

According to U-Phi relation curve, it is determined that obtain �� at i-th electrode_iPressure drop U needed for phase delay_i. The difference of liquid crystal optics multi-beam phased array is powered up mode, it is possible to obtain pressure drop U_iWith the different relation meter formulas of Vi. For PWM(pulse-width modulation) voltage of alternating current powers up mode, pressure drop U_iIt is the electromotive force V on i-th electrode_iWith the root-mean-square value of the difference of Vcomi, that is:

U_i=RMS (Vi-Vcomi) (5)

According to formula (5), calculate grating electrode voltage Vi.

To the liquid crystal optical phased array antenna implementation method of the present invention, carry out simulating, verifying. Assuming that grating number of electrodes is 1920, liquid crystal optical phased array effective pore radius is 110mm, simulation analysis light beam deflection capacity, assuming that wedge deflection angle is 1.2 degree, the beam deflection angle degree in far field is as shown in Figure 3, spot center is at 20.942mrad, deviation 1.95 �� rad, it is achieved that high precision deflection control.

The present invention is directed to the deficiency of available liquid crystal optical phased array antenna in deflection precision and sweep limit, it is achieved the quasi-continuous deflection control of the wave beam high precision of liquid crystal optical phased array, meet satellite optical communication light to the demand of scanning continuity and wave beam deflection precision.

The content not being described in detail in specification sheets of the present invention belongs to the known technology of those skilled in the art.

Claims (1)

1. a liquid crystal optical phased array antenna implementation method, described liquid crystal optical phased array antenna comprises common electrical pole and grating electrode, it is characterised in that, described public electrode is designed to high resistance liquid crystal wedge electrode; The impedance of high resistance liquid crystal wedge electrode is greater than 1000 ��, two electrodes are designed at high resistance liquid crystal wedge electrode two ends, load the voltage with different magnitude of voltage respectively, produce a ramp phase distribution, the equivalent liquid crystal prism adjustable in a hill slope, it is possible to incident wave beam is deflected control continuously; Grating electrode loads and quantizes voltage, it is possible to realize the stepping deflection control of incident wave beam.