CN101299511A - Method for expanding laser output linewidth - Google Patents
Method for expanding laser output linewidth Download PDFInfo
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- CN101299511A CN101299511A CNA2008100986072A CN200810098607A CN101299511A CN 101299511 A CN101299511 A CN 101299511A CN A2008100986072 A CNA2008100986072 A CN A2008100986072A CN 200810098607 A CN200810098607 A CN 200810098607A CN 101299511 A CN101299511 A CN 101299511A
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Abstract
A method for expanding the output linewidth of the laser, used in the technical field of the laser display, includes the following steps: introducing a loss element changing along the wavelength of the laser gain area in the laser cavity, overlapping and compounding the loss curve and the laser medium gain curve in the laser cavity, to cause the laser gain central area with larger cavity loss in the laser cavity, thereby causing the laser wavelength with lower gain in the laser gain bandwidth to obtain the chance of the oscillation starting, consequently widening the output bandwidth of the whole laser. The method of the invention is not only used in the semiconductor pumping intracavity frequency double laser and the fundamental wave output laser in the embodiment, but also is used in the RGB laser of the laser display, which effectively restrains the speckle effect. In addition, the laser has small volume and low cost.
Description
Technical field
The present invention relates to a kind of method of expanding laser output linewidth, this method can be used for laser display.
Background technology
As everyone knows, good, the high directivity of the monochromaticjty of laser, coherence's height.Aspect laser display, the high coherence of laser can produce speckle (Speckle) effect, makes to show that image quality descends, and has a strong impact on visual effect.One document number is that the application for a patent for invention specification of CN101063519A discloses the illuminator that a kind of laser array optical coupling structure is eliminated speckle.This illuminator comprises: the laser of a plurality of emission of lasering beam; Assemble element at each laser light-emitting window front end collimating element of vertical placement with the Laser emission direction and; One buncher, the light-emitting window of each convergent component is connected with the inlet optics of described buncher, and the laser that is used for all lasers are sent carries out boundling; One shimming apparatus for shaping, this shimming apparatus for shaping is connected with the outlet optics of buncher, and the laser that is used for buncher is sent carries out shimming.Though this invention can be eliminated the speckle that laser interference forms, need collimation, convergent component are set outside laser cavity, buncher, shimming apparatus for shaping etc., the volume of elimination device that speckle adopts is still huger, cost is high.
Summary of the invention
The technical problem to be solved in the present invention is: at above-mentioned laser lighting, the existing problem of display system, provide a kind of method of expanding laser output linewidth.
Technical scheme of the present invention is: a kind of method of expanding laser output linewidth, may further comprise the steps: in laser cavity, introduce losser with laser gain central area wavelength change, damage curve that it produces in laser cavity and laser medium gain curve stack are compound, make in the laser cavity laser gain central area that big cavity loss is arranged, thereby make the low wavelength region may of gain in laser cavity, obtain starting of oscillation, to widen laser output linewidth.
The method of described expanding laser output linewidth is the etalon that inclination is set in semiconductor pumped double-frequency laser chamber, and this etalon is as the laser cavity speculum, and its thickness is L, and the reflectivity on left and right two surfaces is respectively R1, R2; Wherein the angle of frequency multiplication light path and etalon reflecting surface normal direction is θ; Change the thickness L of etalon or reflectivity R1, the R2 on left and right two surfaces, can regulate its transmitance; The gradient of regulating same etalon promptly changes the θ value, and scalable sees through centre wavelength; Etalon can be regulated laser cavity actual gain curve as speculum like this.
The method of described expanding laser output linewidth is that the birefringence filter that is made of the polarization polarizer and crystal wave-plate is set in laser cavity, when laser gain central area wavelength X 0 is in the lower scope of birefringence filter transmitance, its laser cavity internal loss is bigger, actual gain reduces, and is beneficial to expanding laser output linewidth.
The method of described expanding laser output linewidth is directly to plate the reflecting medium film to realize gain-adjusted in the laser cavity on the laser chamber mirror, when laser gain central area wavelength X 0 is in the lower scope of deielectric-coating penetration rate, its laser cavity internal loss is bigger, actual gain reduces, and is beneficial to expanding laser output linewidth.
Compare with prior art, the invention has the beneficial effects as follows: the present invention is by improving the loss of laser gain bandwidth center zone optical maser wavelength in laser cavity, make the increase of laser cavity equivalent gain bandwidth come the expanded laser light live width, promptly increase the actual gain bandwidth by the wavelength that suppresses laser gain bandwidth center zone, make in the laser gain bandwidth optical maser wavelength obtain the adjustment vibrator meeting, thereby whole laser output bandwidth is broadened than low gain.The method of the invention not only can be used for semiconductor pumped intracavity frequency doubling laser and the first-harmonic output laser that the foregoing description exemplifies, and can be used for the RGB laser of laser display aspect, and it can effectively suppress speckle (Speckle) effect.In addition, the laser volume of making is little, cost is low.
Description of drawings
Fig. 1 a is the graph of relation of common laser wavelength emission cross section and wavelength;
Fig. 1 b is the cavity loss curve chart of introducing in the laser cavity with wavelength change;
Fig. 1 c is for introducing with laser cavity equivalent gain curve chart behind the cavity loss element of wavelength change for laser cavity is interior;
Fig. 2 be under the common state etalon see through curve chart;
Fig. 3 is for being inserted with the laser structure schematic diagram of etalon in the chamber;
Fig. 4 by on the laser chamber mirror the graph of relation of plating deielectric-coating reflectivity and wavelength;
Fig. 5 a is the birefringence filter construction schematic diagram of being introduced in the laser cavity;
Fig. 5 b is the curve chart of birefringence filter filtering shown in Fig. 5 a.
Embodiment
Expanding laser output linewidth is to reduce the highly effective method of speckle (Speckle) effect.By Principles of Laser as can be known, laser output linewidth is determined by the laser gain halfwidth, is gain medium institute inherent characteristic and the laser gain halfwidth is the laser gain bandwidth, thus common lasers particularly continuous wave laser laser linewidth be fixed value.Generally the live width of semiconductor pumped intracavity frequency doubling laser is very narrow, often has only 1nm, even 0.1nm, for reducing speckle (Speckle) effect, needs expanding laser output linewidth.
The present invention introduces the losser with laser gain central area wavelength change in laser cavity, damage curve that it produces in laser cavity and laser medium gain curve stack are compound, make in the laser cavity laser gain central area that big cavity loss is arranged, thereby make the low wavelength region may of gain in laser cavity, obtain starting of oscillation, to widen laser output linewidth.As shown in Figure 1a, the relation curve C1 of common lasers endovenous laser wavelength emission cross section σ and wavelength X, this common lasers gain curve halfwidth is gain bandwidth Δ λ=λ 2-λ 1 as can be known.Shown in Fig. 1 b, introduce equivalent losser in the common lasers chamber, its damage curve C2 with wavelength change.Shown in Fig. 1 c, introducing equivalent losser in the common lasers chamber effectively reduces laser cavity central area actual gain σ, the equivalent gain curve C is the result of C2 and C1 stack, actual gain bandwidth λ effectively=λ 4-λ 3, this actual gain bandwidth is several times of original gain bandwidth Δ λ as can be known.
As shown in Figure 3, this laser is semiconductor pumped intracavity frequency doubling laser, and its optical routing fundamental frequency light path and frequency multiplication light path are formed; The element that is provided with on the fundamental frequency light path comprises the semiconductor pump laser 101 in left side, the optical coupling system 102, front cavity mirror 103 and the gain medium 104 that set gradually along the pumping laser exit direction; The element that is provided with on the frequency multiplication light path comprises frequency-doubling crystal 106 and the Effect of Back-Cavity Mirror 107 that sets gradually along the frequency doubled light exit direction; The intersection of fundamental frequency light path and frequency multiplication light path is provided with the etalon 105 of inclination, and this etalon 105 is as the laser cavity speculum, and its thickness is L, and the reflectivity on left and right two surfaces is respectively R1, R2; Wherein the angle of frequency multiplication light path and etalon 105 reflecting surface normal directions is θ.Adopt different etalons promptly to change the thickness L of etalon 105 or reflectivity R1, the R2 on left and right two surfaces, can regulate its transmitance; The gradient of regulating same etalon promptly changes the θ value, and scalable sees through centre wavelength.Etalon sees through curve as shown in Figure 2 under the common state, should see through class of a curve and be similar to damage curve C2 among Fig. 1 b, like this when laser gain central area wavelength is in the lower scope of etalon transmitance, its laser cavity internal loss is bigger, actual gain is lower, is beneficial to expanding laser output linewidth.Etalon can be regulated laser cavity actual gain curve as speculum like this.
The present invention also can directly plate the reflecting medium film and realize gain-adjusted in the laser cavity on the laser chamber mirror, present embodiment can be used in the first-harmonic output laser.The relation of deielectric-coating reflectivity R and the wavelength X of plating is seen Fig. 4, this relation curve is similar to the damage curve C2 among Fig. 1 b, like this when laser gain central area wavelength X 0 is in the lower scope of deielectric-coating penetration rate, its laser cavity internal loss is bigger, actual gain is lower, is beneficial to expanding laser output linewidth.So direct plating reflecting medium film can also be regulated laser cavity actual gain curve as losser.
The present invention passes through deielectric-coating, etalon, birefringence filter produce laser cavity wavelength loss curve and the stack of laser gain curve is compound, by increasing laser gain central area wavelength loss, make the lower wavelength light of gain in laser cavity, obtain starting of oscillation, thereby widen laser output linewidth.The method of the invention not only can be used for semiconductor pumped intracavity frequency doubling laser and the first-harmonic output laser that the foregoing description exemplifies, and can be used for RGB (three primary colors) laser of laser display aspect, it can effectively suppress speckle (Speckle) effect.In addition, the laser volume of making is little, cost is low.
Claims (5)
1, a kind of method of expanding laser output linewidth, it is characterized in that may further comprise the steps: in laser cavity, introduce losser with laser gain central area wavelength change, damage curve that it produces in laser cavity and laser medium gain curve stack are compound, make in the laser cavity laser gain central area that big cavity loss is arranged, thereby make the low wavelength region may of gain in laser cavity, obtain starting of oscillation, to widen laser output linewidth.
2, the method for expanding laser output linewidth according to claim 1, it is characterized in that: the etalon that in semiconductor pumped double-frequency laser chamber, is provided with inclination, this etalon is as the laser cavity speculum, and its thickness is L, and the reflectivity on left and right two surfaces is respectively R1, R2; Wherein the angle of frequency multiplication light path and etalon reflecting surface normal direction is θ; Change the thickness L of etalon or reflectivity R1, the R2 on left and right two surfaces, can regulate its transmitance; The gradient of regulating same etalon promptly changes the θ value, and scalable sees through centre wavelength; Etalon can be regulated laser cavity actual gain curve as speculum like this.
3, the method for expanding laser output linewidth according to claim 1, it is characterized in that: in laser cavity, be provided with the birefringence filter that constitutes by the polarization polarizer and crystal wave-plate, when laser gain central area wavelength X 0 is in the lower scope of birefringence filter transmitance, its laser cavity internal loss is bigger, actual gain reduces, and is beneficial to expanding laser output linewidth.
4, the method for expanding laser output linewidth according to claim 1, it is characterized in that: directly plating reflecting medium film is realized gain-adjusted in the laser cavity on the laser chamber mirror, when laser gain central area wavelength X 0 is in the lower scope of deielectric-coating penetration rate, its laser cavity internal loss is bigger, actual gain reduces, and is beneficial to expanding laser output linewidth.
5, according to the method for any one described expanding laser output linewidth in the claim 1 to 4, it is characterized in that: said method not only can be used for semiconductor pumped intracavity frequency doubling laser and first-harmonic output laser, and can be used for the RGB laser of laser display aspect.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008100986072A CN101299511A (en) | 2008-05-30 | 2008-05-30 | Method for expanding laser output linewidth |
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| Application Number | Priority Date | Filing Date | Title |
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| CNA2008100986072A CN101299511A (en) | 2008-05-30 | 2008-05-30 | Method for expanding laser output linewidth |
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| CN101299511A true CN101299511A (en) | 2008-11-05 |
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| CNA2008100986072A Pending CN101299511A (en) | 2008-05-30 | 2008-05-30 | Method for expanding laser output linewidth |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101656394B (en) * | 2009-09-18 | 2011-08-10 | 青岛海信电器股份有限公司 | Laser reducing speckle |
| CN110280894A (en) * | 2019-07-02 | 2019-09-27 | 苏州全视智能光电有限公司 | A kind of laser linewidth Automatic adjustment method |
| CN111683235A (en) * | 2020-06-03 | 2020-09-18 | 青岛海信激光显示股份有限公司 | Laser projection device |
-
2008
- 2008-05-30 CN CNA2008100986072A patent/CN101299511A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101656394B (en) * | 2009-09-18 | 2011-08-10 | 青岛海信电器股份有限公司 | Laser reducing speckle |
| CN110280894A (en) * | 2019-07-02 | 2019-09-27 | 苏州全视智能光电有限公司 | A kind of laser linewidth Automatic adjustment method |
| CN110280894B (en) * | 2019-07-02 | 2021-07-02 | 苏州全视智能光电有限公司 | Automatic laser line width adjusting method |
| CN111683235A (en) * | 2020-06-03 | 2020-09-18 | 青岛海信激光显示股份有限公司 | Laser projection device |
| CN111683235B (en) * | 2020-06-03 | 2022-04-05 | 青岛海信激光显示股份有限公司 | Laser projection device |
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Open date: 20081105 |