第十二讲 啁啾脉冲放大器
合集下载
相关主题
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
12. Chirped Pulse Amplication(CPA) and Petawatt Lasers
Chirped pulse amplication (CPA) Pulse stretching method Pulse compression Regenerate amplification Multiple amplification Gain narrowing Optical parametric CPA Petawatt laser example
•CPA based on Nd:glass: 1053 nm, 400 fs, >200 J, one
shot per hours;
• OPCPA based on KD*P: 40-80 fs; 910 nm or 1053 nm,
35 J; single shot
.
Petawatt example: petawatt hybrid OPCPA-Glass laser-Texas
四分之一波电压放大器
.
Regenerate amplifier
半波电压再生放大器
.
Optical Isolator
Function: (1) avoid the amplifed light feeding back to oscillator (2) Split seeding and amplified beam
.
Laser intensity evolution
CPA Lasers
引自G. Mourou
.
ICUIL 2008
Chirped pulse amplification Scheme
.
CPA: Why?
1. Efficient amplification 2. Avoid optical damage in amplification
3.08 ns
.
Diffraction-grating pulse compressor
The grating pulse compressor also has negative second-order phase.
Grating #2
d2
d
2
0
2c0 3 2d2co L2s(esp')
where d = grating spacing (same for both gratings)
t = t [d/d]–1 = 0.44 [d/d]–1 = 0.44 2/c0
where we’ve neglected the minus sign since we’re computing the bandwidth, which is inherently positive. So the bandwidth is:
.
Petawatt laser facilities in the world
FW H M0.44t02/c0
0.4402/c0 LG VM
G VM c0 0n(0)1 2n(0/2)
FW H M
0.440/L n(0)1 2n(0/2)
Calculating the bandwidth by considering the GVM yields the same result as the phase-matching bandw. idth!
medium due to high optical intensity 3. Reduce the nonlinear effect in
medium
.
Pulse stretching by grating pair
.
Pulse to be strecthed due to GDD
30 fs + 109 fs2
.
Multi-pass amplifier (1)
.
Power amplifier
.
.
Gain narrowing
.
Suppression of gain narrowing
.
.
OPCPA
Nonlinear crystal
OPCPA characteristics: (1) high gain ( >1000 for single pass) (2) large amplifying bandwidth, wavelength designable (3) Low energy conversion efficiency (4) requires synchronization between pumping and seeding laser
.
Petawatt scheme
.
OPCPA scheme
.
Nd:glass hybrid amplifier
.
Suppression gain narrowing by hybrid amplification
.
Compression grating
.
Results
.
Petawatt laser facilities
Lsep
Note that, as in the prism pulse compressor, the larger Lsep, the larger the negative GDD.
.
Grating #1
Mode locked oscillator as seeding light
.
Regenerate amplifier
.
Coupling wave equation
.
Group-velocityቤተ መጻሕፍቲ ባይዱmismatch limits
bandwidth.
Take the second-harmonic pulse to have a Gaussian intensity, for which t =
0.44. Rewriting in terms of the wavelength,
560 TW OPCPA by Russia
.
Main Routes for Petawatt laser
•CPA based on Ti:Sapphire: 800 nm wavelength; broad
bandwidth (30 fs), repetitive (0.1 Hz); 30 J
Chirped pulse amplication (CPA) Pulse stretching method Pulse compression Regenerate amplification Multiple amplification Gain narrowing Optical parametric CPA Petawatt laser example
•CPA based on Nd:glass: 1053 nm, 400 fs, >200 J, one
shot per hours;
• OPCPA based on KD*P: 40-80 fs; 910 nm or 1053 nm,
35 J; single shot
.
Petawatt example: petawatt hybrid OPCPA-Glass laser-Texas
四分之一波电压放大器
.
Regenerate amplifier
半波电压再生放大器
.
Optical Isolator
Function: (1) avoid the amplifed light feeding back to oscillator (2) Split seeding and amplified beam
.
Laser intensity evolution
CPA Lasers
引自G. Mourou
.
ICUIL 2008
Chirped pulse amplification Scheme
.
CPA: Why?
1. Efficient amplification 2. Avoid optical damage in amplification
3.08 ns
.
Diffraction-grating pulse compressor
The grating pulse compressor also has negative second-order phase.
Grating #2
d2
d
2
0
2c0 3 2d2co L2s(esp')
where d = grating spacing (same for both gratings)
t = t [d/d]–1 = 0.44 [d/d]–1 = 0.44 2/c0
where we’ve neglected the minus sign since we’re computing the bandwidth, which is inherently positive. So the bandwidth is:
.
Petawatt laser facilities in the world
FW H M0.44t02/c0
0.4402/c0 LG VM
G VM c0 0n(0)1 2n(0/2)
FW H M
0.440/L n(0)1 2n(0/2)
Calculating the bandwidth by considering the GVM yields the same result as the phase-matching bandw. idth!
medium due to high optical intensity 3. Reduce the nonlinear effect in
medium
.
Pulse stretching by grating pair
.
Pulse to be strecthed due to GDD
30 fs + 109 fs2
.
Multi-pass amplifier (1)
.
Power amplifier
.
.
Gain narrowing
.
Suppression of gain narrowing
.
.
OPCPA
Nonlinear crystal
OPCPA characteristics: (1) high gain ( >1000 for single pass) (2) large amplifying bandwidth, wavelength designable (3) Low energy conversion efficiency (4) requires synchronization between pumping and seeding laser
.
Petawatt scheme
.
OPCPA scheme
.
Nd:glass hybrid amplifier
.
Suppression gain narrowing by hybrid amplification
.
Compression grating
.
Results
.
Petawatt laser facilities
Lsep
Note that, as in the prism pulse compressor, the larger Lsep, the larger the negative GDD.
.
Grating #1
Mode locked oscillator as seeding light
.
Regenerate amplifier
.
Coupling wave equation
.
Group-velocityቤተ መጻሕፍቲ ባይዱmismatch limits
bandwidth.
Take the second-harmonic pulse to have a Gaussian intensity, for which t =
0.44. Rewriting in terms of the wavelength,
560 TW OPCPA by Russia
.
Main Routes for Petawatt laser
•CPA based on Ti:Sapphire: 800 nm wavelength; broad
bandwidth (30 fs), repetitive (0.1 Hz); 30 J