CN203786405U - Device for producing perfect Laguerre-Gaussian beam - Google Patents
Device for producing perfect Laguerre-Gaussian beam Download PDFInfo
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- CN203786405U CN203786405U CN201420174839.2U CN201420174839U CN203786405U CN 203786405 U CN203786405 U CN 203786405U CN 201420174839 U CN201420174839 U CN 201420174839U CN 203786405 U CN203786405 U CN 203786405U
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- laguerre
- gaussian beam
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- gaussian
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Abstract
The utility model relates to a device for producing a perfect Laguerre-Gaussian beam. A Gaussian beam emitted by a laser device sequentially passes a beam intensity adjusting attenuation sheet and a beam expander and further passes a spatial light modulator, a computer-generated hologram used for optical field adjusting and controlling is loaded on a liquid crystal display screen of the spatial light modulator, and performs optical field adjusting and controlling on the Gaussian beam subjected to beam expansion; the beam after optical field adjusting and controlling passes a circular aperture diaphragm, and first-stage diffracted beam emitted by the spatial light modulator is intercepted by the circular aperture diaphragm to obtain a hollow Laguerre-Gaussian beam; and the hollow Laguerre-Gaussian beam passes a spiral phase plate and a focusing convex lens, and a perfect Laguerre-Gaussian beam is output. The device generates the perfect Laguerre-Gaussian beam by directly utilizing the hollow beam carried with orbital angular momentum, and the method is simple and reliable; the device is simple in structure and easy to adjust, and has good stability; and the beam produced by the device can be used in the fields of particle trapping, free space optical communication, beam transmission characteristic research and the like.
Description
Technical field
The utility model relates to a kind of optical system, particularly a kind of generation device of perfect Laguerre-Gaussian beam, and the light beam producing can be applicable to the fields such as particle-capture, free space optical communication, beam propagation property research.
Background technology
Laguerre-Gaussian beam has helical phase structure, on mathematic(al) representation, is embodied in its phase factor and has and gyrobearing angle
be directly proportional one
, wherein
iimaginary unit (-1 open root),
mbe generally integer, also referred to as topological charge number, its correspondence the number of turns of phase rotating in an optical wavelength.Light beam presents screw type wavefront properties around phase singularity, and theoretical analysis and experimental verification show, each photon in this class light beam has definite orbital angular momentum
(
,
for Planck constant,
circular constant).It is zero because interference disappears mutually that its special phase structure makes its central light strength, thereby makes light intensity center be rendered as hollow state.
Under cylindrical coordinate, the Electric Field Distribution of Laguerre-Gaussian beam on surface of light source is:
Wherein,
with
be respectively radial coordinate and angle coordinate,
iimaginary unit,
zfor transmission range,
for fundamental-mode gaussian beam (
time) beam waist,
represent that mode step is
mwith
plaguerre polynomials,
mfor topological charge number,
pfor characteristic quantity subnumber,
qfor coefficient.When
time, the Electric Field Distribution of expression standard Laguerre-Gaussian beam; And work as
time, represent the Electric Field Distribution of perfect Laguerre-Gaussian beam.
Perfect Laguerre-Gaussian beam (Elegant Laguerre-Gaussian beams) is proposed by Siegman, what be different from standard Laguerre-Gaussian beam is, perfect Laguerre-Gaussian beam comprises the polynomial expression with complex argument, and in the polynomial expression that the latter comprises, independent variable is real number.At optical field, since perfect Laguerre-Gaussian beam is suggested, it has caused people's extensive concern with its important character, and the phase structure of its uniqueness and orbital angular momentum characteristic are having very important effect aspect particulate slewing maneuver and free space optical communication.Aspect light catches, Laguerre-Gaussian beam has the mechanical characteristic of orbital angular momentum based on it, can be used as " optics spanner " is applied to particulate and controls, C. Zhao etc. proposes by changing the coherence of the perfect Laguerre-Gaussian beam of partial coherence, to catch the Rayleigh Particles that refractive index is greater than or less than surrounding medium.At optical communication field, J. Qu etc. has studied the transport property of perfect Laguerre-Gaussian beam in turbulent atmosphere in theory, the impact that the perfect Laguerre-Gaussian beam of discovery high-order mode is subject to turbulent atmosphere can reduce, and under identical condition, it is faster that standard Laguerre-Gaussian beam is dispersed than perfect Laguerre-Gaussian beam, and conclusion contributes to the long research apart from free space optical communication.
Generation for perfect Laguerre-Gaussian beam is theoretical, and the method that M. A. Bandres etc. utilizes Shin and Felsen to propose, introduces high-order complex source, produces radial mode number
nwith angle pattern count
mperfect Laguerre-Gauss ripple, obtain the integration and differentiation expression formula of perfect Laguerre-Gauss ripple, and determined the paraxial approximation of perfect Laguerre-Gaussian beam and the non-paraxial correction on first three rank from integral expression.Yet perfect Laguerre-Gaussian beam can not represent stable spherical mirror optical resonator pattern, for its research, be all theoretic substantially, the research that experiment produces perfect Laguerre-Gaussian beam has no report at present.
Summary of the invention
Problem to be solved in the utility model is to overcome the blank that prior art exists, and provides a kind of principle simple, easily realizes, and has the generation device of the perfect Laguerre-Gaussian beam of actual application value, its simple in structure, low cost of manufacture.
To achieve the above object of the invention, the technical solution of the utility model is to provide a kind of device that produces perfect Laguerre-Gaussian beam, its structure is: the Gaussian beam that the diode pumped solid state laser that power is adjustable sends, successively after beam intensity regulates attenuator and beam expander, pass through again spatial light modulator, in the LCDs of spatial light modulator, load the calculation holographic sheet for carrying out light field regulation and control, the Gaussian beam after expanding is carried out to light field regulation and control; Light beam after regulation and control is by circular hole diaphragm, then process spiral phase plate and focusing convex lens, exports perfect Laguerre-Gaussian beam.
In a preferred version of the present utility model, described spatial light modulator is transmission-type spatial light modulator; It is circular graded density optical filter that described beam intensity regulates attenuator; Described beam expander is two convex lens.Between beam intensity regulator and beam expander, plane mirror is set.
In technical solutions of the utility model, laser instrument sends Gaussian beam, through attenuator, regulates beam intensity, then through expanding, arrives spatial light modulator, carries out the rear outgoing of light field regulation and control in the LCDs of spatial light modulator; Utilize the intercepting of circular hole diaphragm by the first order diffracted beam of spatial light modulator outgoing, obtain hollow Gaussian beam; Hollow Gaussian beam carries out phase-modulation through spiral phase plate, obtains carrying the hollow beam of orbital angular momentum; The hollow beam planoconvex lens that carries orbital angular momentum focuses on, and obtains perfect Laguerre-Gaussian beam.
The principle of the utility model foundation is as follows:
Carry the hollow beam of orbital angular momentum in transmission range
zthe Electric Field Distribution at=0 place is defined as formula (1):
(1)
Wherein
e 0constant,
with
respectively radial coordinate and angle coordinate,
iimaginary unit (-1 open root),
nthe light beam exponent number that carries the hollow beam of orbital angular momentum,
mtopological charge number,
w 0be fundamental-mode gaussian beam beam waist (
m=
n=0 o'clock).
When free-space propagation, vortex beams far-field approximation (
) under Electric Field Distribution be formula (2):
(2)
Wherein
with
respectively radial coordinate and the angle coordinate of exit facet,
iimaginary unit (-1 open root),
wave number,
circular constant,
wavelength,
represent that mode step is
with
nlaguerre polynomials,
mfor topological charge number,
nit is light beam exponent number.
with
,
wwith
respectively that transmission range is
ztime spot radius and Rayleigh range.
From formula (2), can learn, when
time, the hollow beam that carries orbital angular momentum is evolved into the Electric Field Distribution of perfect Laguerre-Gaussian beam in the far-field distribution of free space, illustrate that we can utilize the hollow beam that carries orbital angular momentum to produce perfect Laguerre-Gaussian beam as virtual light source.
Technical solutions of the utility model are by focusing, to carry the hollow beam of orbital angular momentum, at focus place, produce perfect Laguerre-Gaussian beam.
Due to the utilization of technique scheme, a kind of device tool that produces perfect Laguerre-Gaussian beam that the utility model provides has the following advantages:
1, technical solutions of the utility model directly utilize the hollow beam that carries orbital angular momentum to produce perfect Laguerre-Gaussian beam, method is simple, reliably, the light beam producing can be applicable to the fields such as particle-capture, free space optical communication, beam propagation property research.
The generation device of the perfect Laguerre-Gaussian beam 2, providing is simple in structure, is easy to adjust good stability.
Accompanying drawing explanation
Fig. 1 is the structural representation of the generation device of a kind of perfect Laguerre-Gaussian beam of providing of the utility model embodiment;
Fig. 2 be the utility model embodiment provide for light beam being carried out to the calculation holographic sheet of light field regulation and control;
Fig. 3 is the surface of intensity distribution of the hollow beam that carries orbital angular momentum that produces in the utility model embodiment;
Fig. 4 is the surface of intensity distribution of the perfect Laguerre-Gaussian beam that produces in the utility model embodiment;
Fig. 5 is the surface of intensity distribution of the perfect Laguerre-Gaussian beam of generation in theory that the present embodiment provides.
In Fig. 1: 1, laser instrument; 2, attenuator; 3, level crossing; 4,5 and 9, convex lens; 6, spatial light modulator; 7, circular hole diaphragm; 8, spiral phase plate; 10, laser beam analyzer; 11 and 12, computing machine.
Embodiment
Below in conjunction with drawings and Examples, technical solutions of the utility model are further described.
Embodiment 1:
Referring to accompanying drawing 1, it is the structural representation of the generation device of a kind of perfect Laguerre-Gaussian beam of providing of the present embodiment, this device comprises: laser instrument 1, attenuator 2, level crossing 3, convex lens 4,5 and 9, spatial light modulator 6, circular hole diaphragm 7, spiral phase plate 8, laser beam analyzer 10, computing machine 11 and 12.
Laser instrument 1 is adjustable diode pumped solid state laser (the peak power 1.8W of power, wavelength is 532nm), the Gaussian Beam attenuator 2 sending regulates beam intensity, then changes the direction of propagation through level crossing 3 reflections, and described attenuator 2 is circular graded density optical filter; Gaussian Beam is crossed convex lens 4 and 5 and is expanded, convex lens 4 and 5 also can by beam expander (as model Beam-Expander 2-8 *, 532nm, LINOS) replace; Gaussian beam after expanding is by spatial light modulator 6, described spatial light modulator 6 is transmission-type LCD space light modulator (BQ-SLM1024), by computing machine 11 by software loading calculation hologram sheet in the LCDs of spatial light modulator, Gaussian beam after expanding is carried out to light field regulation and control, regulate and control the value of light beam exponent number n, referring to accompanying drawing 2, it be the present embodiment provide for light beam being carried out to the calculation holographic sheet of light field regulation and control, make light beam exponent number n=2; Light beam after regulation and control is by circular hole diaphragm 7, and intercepting first order diffracted beam, obtains hollow Gaussian beam; Hollow Gaussian beam carries out phase-modulation through spiral phase plate 8, modulate topological charge and count the value of m, obtain carrying the hollow beam of orbital angular momentum, (charge 2 for described spiral phase plate, Model VPP-2, RPC Photonics) electric charge parameter is 2, the phase-modulation that carries out to hollow Gaussian beam, make its topological charge count m=2, obtain carrying the hollow beam of orbital angular momentum; The hollow beam planoconvex lens 9 that carries orbital angular momentum focuses on, and obtains perfect Laguerre-Gaussian beam, and in the present embodiment, the focal length that focuses on convex lens 9 is 400mm.The perfect Laguerre-Gaussian beam that the device that the present embodiment is provided produces is measured, can adopt laser beam analyzer 10 and be connected with computing machine 12, laser beam analyzer 10 is for observing and take the light distribution of the hollow beam and the perfect Laguerre-Gaussian beam that carry orbital angular momentum.
Utilize said apparatus that the present embodiment provides to produce the method for perfect Laguerre-Gaussian beam, concrete operation step is as follows:
1, by laser instrument 1, send Gaussian beam, through attenuator 2, regulate beam intensity, then 3 reflections change the direction of propagation through level crossing, folded light beam expands through convex lens 4 and 5.
2, the Gaussian beam expanding arrives spatial light modulator 6, software program by computing machine 11 is loaded into calculation holographic sheet in the LCDs of spatial light modulator 6, position and the size of calculation holographic sheet on the position of the LCDs of adjusting spatial light modulator 6 and display screen, described Gaussian beam is just in time radiated on calculation holographic sheet, carries out the rear outgoing of light field regulation and control.As accompanying drawing 2 is calculation holographic sheet used in the present embodiment, regulation and control light beam exponent number n is n=2.
3, the light beam by spatial light modulator 6 outgoing passes through circular hole diaphragm 7, and intercepting first order diffracted beam, obtains hollow Gaussian beam.
4, hollow Gaussian beam carries out phase-modulation through spiral phase plate 8, and it is m=2 that modulation topological charge is counted m, and obtaining parameter is the hollow beam that carries orbital angular momentum of m=2, n=2.
5, near spiral phase plate 8, place beam distribution instrument 10, laser beam analyzer 10 is connected with computing machine 12 with measurement, observation and the light distribution of taking the hollow beam that carries orbital angular momentum, referring to accompanying drawing 3, it is the surface of intensity distribution of the hollow beam that carries orbital angular momentum that produces in the present embodiment.
6, near spiral phase plate 8, place convex lens 9, to carrying the hollow beam of orbital angular momentum, focus on, beam distribution instrument 10 is positioned over to the focus place (beam propagation distance z=f=400mm) of convex lens 9, observation and the light distribution of taking perfect Laguerre-Gaussian beam, referring to accompanying drawing 4, it is the surface of intensity distribution of the perfect Laguerre-Gaussian beam that produces in the present embodiment.
7,, referring to accompanying drawing 5, it is the surface of intensity distribution of the perfect Laguerre-Gaussian beam of generation in theory providing in the present embodiment.Accompanying drawing 4 contrasts with accompanying drawing 5, and experiment and theory relatively can prove, what the present embodiment produced is that parameter is the perfect Laguerre-Gaussian beam of m=2, n=2.
Claims (5)
1. a device that produces perfect Laguerre-Gaussian beam, it is characterized in that: the Gaussian beam that the diode pumped solid state laser that power is adjustable (1) sends, successively after beam intensity regulates attenuator (2) and beam expander, again by spatial light modulator (6), in the LCDs of spatial light modulator (6), load the calculation holographic sheet for carrying out light field regulation and control, the Gaussian beam after expanding is carried out to light field regulation and control; Light beam after regulation and control passes through circular hole diaphragm (7), then passes through spiral phase plate (8) and focus on convex lens (9), exports perfect Laguerre-Gaussian beam.
2. a kind of device that produces perfect Laguerre-Gaussian beam according to claim 1, is characterized in that: beam intensity regulates attenuator (2) for circular graded density optical filter.
3. a kind of device that produces perfect Laguerre-Gaussian beam according to claim 1, is characterized in that: described beam expander is two convex lens (4 and 5).
4. a kind of device that produces perfect Laguerre-Gaussian beam according to claim 1, is characterized in that: between beam intensity regulator (2) and beam expander, plane mirror (3) is set.
5. a kind of device that produces perfect Laguerre-Gaussian beam according to claim 1, is characterized in that: described spatial light modulator is transmission-type spatial light modulator.
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| CN201420174839.2U CN203786405U (en) | 2014-04-11 | 2014-04-11 | Device for producing perfect Laguerre-Gaussian beam |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103941405A (en) * | 2014-04-11 | 2014-07-23 | 苏州大学 | Method and device for generating perfect Laguerre-Gaussian beam |
| CN105445941A (en) * | 2015-12-18 | 2016-03-30 | 南京雨花肿瘤防治研究所 | High power laser attenuator |
| CN106444052A (en) * | 2016-11-16 | 2017-02-22 | 华侨大学 | Optical system capable of generating order-adjustable defocused beams |
| CN110987927A (en) * | 2019-11-15 | 2020-04-10 | 南京大学 | Rotating object imaging system based on Laguerre Gaussian transformation |
| CN112125506A (en) * | 2020-09-23 | 2020-12-25 | 苏州大学 | Preparation method of spiral phase modulation sheet and method for generating vortex light beam by using spiral phase modulation sheet |
| CN112326024A (en) * | 2020-09-25 | 2021-02-05 | 山东师范大学 | Device and method for simultaneously measuring topological load size, positive load size and negative load size of vortex light beam |
| CN112904364A (en) * | 2021-01-19 | 2021-06-04 | 湖南大学 | Correlation imaging scheme of hollow Gaussian modulation source under atmospheric turbulence |
-
2014
- 2014-04-11 CN CN201420174839.2U patent/CN203786405U/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103941405A (en) * | 2014-04-11 | 2014-07-23 | 苏州大学 | Method and device for generating perfect Laguerre-Gaussian beam |
| CN105445941A (en) * | 2015-12-18 | 2016-03-30 | 南京雨花肿瘤防治研究所 | High power laser attenuator |
| CN106444052A (en) * | 2016-11-16 | 2017-02-22 | 华侨大学 | Optical system capable of generating order-adjustable defocused beams |
| CN110987927A (en) * | 2019-11-15 | 2020-04-10 | 南京大学 | Rotating object imaging system based on Laguerre Gaussian transformation |
| CN112125506A (en) * | 2020-09-23 | 2020-12-25 | 苏州大学 | Preparation method of spiral phase modulation sheet and method for generating vortex light beam by using spiral phase modulation sheet |
| CN112326024A (en) * | 2020-09-25 | 2021-02-05 | 山东师范大学 | Device and method for simultaneously measuring topological load size, positive load size and negative load size of vortex light beam |
| CN112326024B (en) * | 2020-09-25 | 2022-07-22 | 山东师范大学 | Device and method for simultaneously measuring topological load size and positive and negative of vortex light beam |
| CN112904364A (en) * | 2021-01-19 | 2021-06-04 | 湖南大学 | Correlation imaging scheme of hollow Gaussian modulation source under atmospheric turbulence |
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Granted publication date: 20140820 Termination date: 20170411 |
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