Oscillator stability & ASE Reduction

Xiangyu Zhou

20. Nov. 2015

Layout

Upgrade laser system, undergroundYb-doped fiber & Thin-disk Yb:YAG @ 1030 nm

New laser system, on the groundYb-doped fiber & Rod Nd:YAG @ 1064 nmYb-doped fiber & Thin-disk Yb:YAG @ 1030 nm

Old underground laser systemYb-doped fiber oscillator with

Transmission grating

Yb-doped fiber pre amplifier

Yb-doped fiber main amplifier

Pulse picker

Yb:YAG thin-disk regenerative amplifier

Yb:YAG thin-disk multipass amplifier

SHG

Synchronization system

SHGRF GUN

51.9 MHz

2, 5, 25, 50 HzSingle or Double bunch

0.2 nJ @ 1037 nm

Yb-doped fiber main amplifier

Transmission grating pair

stretcher

2856 MHz triggerFrom Accelerator

Yb-doped fiber pre amplifier

>μJ @ 1037 nm

New underground laser systemYb-doped fiber oscillator with

Transmission grating

Yb-doped fiber pre amplifier

Yb-doped fiber main amplifier

Pulse picker

Yb:YAG thin-disk multi-pass cavity amplifier

Yb:YAG thin-disk multipass amplifier ×3

SHG

Synchronization system

SHGRF GUN

51.9 MHz

2, 5, 25, 50 HzSingle or Double bunch

0.2 nJ @ 1037 nm

Yb-doped fiber main amplifier

Transmission grating pair

stretcher

2856 MHz triggerFrom Accelerator

Yb-doped fiber pre amplifier

>μJ @ 1037 nm

Pulse picker

10 MHz

Fiber pre-amplifier

LD Pump

SMF

WDMcoupler

WDMcoupler

700 mW @ 976 nm

Yb-doped fiber

WDMcoupler

Splitter Coupler

Splitter Coupler

50%50%

70%30%

50%35%15%

• Reduce the ASE• Increase the amp efficiency• All the fibers are coupled

The issue in pulse picker

INTENSITY MODULATOR ：　 NIR-MX-LN-10

51.98 MHz10 MHz

51.98 MHz

Double bunch

96 ns

E.O. voltage

Semiconductor Optics amplifier (SOA) Pulse Picker

SOA input signal generation

Discriminator Gate generator 1 Gate generator 3 Level adapter

Gate generator 2Reference signal10MHz

Semiconducter Optics amplifier (SOA) Pulse Picker

Cut & Soldering

SOA-1020-110-HI-27dB (Innolume)SOA chip mount

Input: 3 mWOutput: 3 mW52 MHz 10.38 MHz

Oscillator output

Spectrum Pulse train

* Broadband and Stable

Output power8.2mW

* Repetition frequency : 51.9MHz

Yb single mode fiber amp (3stage) output

Spectrum Pulse train

Output power85mW

* Repetition frequency : 10MHz* Wavelength Center : 1030nm , FWHM : 2nm

Yb-doped PCF amp & EO module Pulse picker

1030nm Fiber laser system

Improvement• Increase the stability of oscillator• Reduce the ASE of pre-amplifier• Increase the amp efficiency• Reduce the noise signal of 52 MHz (Pulse picker)

Yb fiber laser system on the ground

Menlo1030nm oscillator

Grating stretcher(Transmission)

SOApulse picker

Yb single mode fiber amp

Yb-doped double clad fiber amp

Repetition frequency114.24MHz

Wavelength selection1030nm & 1064nm

Repetition frequency 10MHz

Nd:YAG regenerative amplifier

EO modulepulse picker

Repetition frequency : 10Hz Yb:YAG Thin disk

regenerative amplifier

1030nm oscillator(ANDi type)

1064nm oscillator(ANDi type)

Output(1030nm)

Output(1064nm)

ASE rejection grating pair

1030nm1064nm

1064nm

Fiber part

Produce from MenlosystemsORANGE-Comb-250

• 1025-1050nm

• ~30mW

• 1-4ps

• 114.24MHz&2,856MHz

SYNCRONIZATION

New design Oscillator

Dissipative Soliton

Self-similar

All-normal-dispersion (ANDi) Oscillator

Yb-doped Fiber Oscillator

Breathing ratio 　>100

Breathing ratio 　<10

Oscillator for 1030 nm

CW oscillation Modelock oscillation

Bandpass filter: Semrock 1030nm (LL01-1030-12.5)• Tabs > 90% 1030 nm• FWHM of 3.9 nmOutput power > 130mW

1064nm Oscillator (ANDi type)

1064nm oscillator(ANDi type)

Spectrum

Pump power [mW]

(LD current [mA])

Output power [mW]

460(700)

75.2

Pulse train

Bandpass filter: Semrock 1064nm (LL01-1064-12.5)• Tabs > 90% 1064 nm• FWHM of 3.9 nm

The spectrum of the oscillators

◆High output power ◆ Tunable center wavelength

Selection of Oscillator

Selection of oscillatorMenlo oscillator

orangeANDi

oscillator1064nm

ANDi oscillator1030nm

Output:30mW @Menlo110mW @1030nm75mW @1064nm

Grating stretcher

Simplified schematic2nm@1030nm 0.5nm@1064nm

SOA pulse picker & Yb single mode fiber amp

Yb single mode fiber amp

SOA input[μW]

SOA output[μW]

Yb single mode amp output

[mW]

1030nm 330 400 135

1064nm 250 710 46

SOA pulse picker

1030nm 1064nm

Repetition frequency : 10MHz ASE of SOA

Grating pair for ASE remove @ 1064nm

ASE spectrum of SOA

1064nm pulse train

Before(power : 82mW)

After(power : 46mW)

Yb-doped double clad fiber amp

Pulse train Spectrum

Output power : 1.0 W(Pump power : 4W)

Fiber laser system layout on the ground

3 oscillators (100 MHz) 2 fiber system for 1030nm/1064nm SOA pulse picker Yb-doped fiber amplifier (~1.0 W)