Second Harmonic Generation
Visible Tunable Laser System
Hänsch Couillard Locking
Fast Relocking Scheme

Scientific Lasers

TEC 1000

Vorsprung durch Innovation

Second harmonic generation
mechanisms
Second harmonic generation

Why second harmonic
Generation?
Diode lasers are compact, robust,versatileand comparably cheap.
However, the spectral coverage oflaser diode omits some important
wavelength region. UV, blue, yellow
and green light (UV - 620nm) cannot
be directly accessed with diode lasers.

Cavity mirror

The solution: SHG

SHG Crystal

SHG system schematics

Sacher Lasertechnik Group offers
complete laser systems with a second
harmonic generation stage to allow for
laser sources in the above mentioned
wavelength regions.
These stages can also be combined toaccess the quadrupled frequency.

How does it work?

Pump Laser

Cavity mirror

SHG Crystal

Hänsch-Couillaud-Locking

Second harmonic generation exploits
nonlinear features of certain materials
which lead to a generation of doubled
frequency. An easy-to-understandway of explaining is that two photons
are absorbed whereas only one isemitted, which then carries the doubleenergyand thus is at double
frequency.
For different wavelengths, different
material has to be used. Therefore
every such system is tailored to theindividual customer.

Optical cavity

rotated linear
polarizationof master laser

quarter
waveplatepolarizing
beamsplitterl/4
on resonance
off resonancephotodiodes

The use of an optical cavity isparamount for SHG generation since
the nonlinear conversion efficiency is
generally low. Therefore, the pump
power is enhanced by using an opticalcavity which is locked to the pumplaser source. The locking mechanismis the Hänsch-Couillaud locking,which allows for modulation freestabilization of the cavity to the pumplaser.

SHG system for Ca cooling & trapping
wavelength 423nm, power 120mW
System performance

Excellent beam quality,
typically M² < 1.3

Low RMS noise,
typically < 3%

High stability &short warm-up time
typically < 20 min.

Spectral coverage
1200

800
600
400
200

W a v e l e n g th / n m

59
055
053
049
045
7,
5440

42
541
540
539
7,
539
038
533
5032
5SHGPower / mW

1000

ApplicationsAtomcoolingandtrapping,(Ca,Sr,Rb..)
Interferometry
Lithography
Outlook
Fourth harmonic generation (FHG) further extends the spectral coverage byaccessing deep UV radiation- UV wavelengths between190 and 270nm- UV power up to 50mW (depending on wavelength)

About Sacher Lasertechnik
Company Profile
Sacher Lasertechnik is a leading manufacturer of tunable external cavity diodelasers (ECDLs) with experience since 1992. The product range includes antireflection coated diode lasers, external cavity diode lasers in Littrow and in
Littman/Metcalf configuration as well as laser driver electronics and sophisticatedmeasuring electronics.
Please contact us with your measurement requirements. We would be proud
to support you with our competence.

Please contact us or our local representative
Sacher LasertechnikGmbH
Rudolf-Breitscheid-Str. 1-5
D-35037 Marburg/Lahn
Germany
Tel.: +49 6421 305 - 0
Fax: +49 6421 305299

Sun InstrumentS, Inc.

Sacher Lasertechnik
LLC
5765 Equador Way
Buena Park, CA90620
U. S. A.
Tel.: 1-800-352-3639
Fax: 1-714-670-7662

Tel:03-5436-9361 Fax:03-5436-9364 E-mail:sun@sun-ins.com

Email: contact@sacher-laser.com
Web: http://www.sacher-laser.com

www.sun-ins.c om