Alpes Lasers QUANTUM CASCADE User manual

QUANTUM CASCADE LASER USER’SMANUAL
Version number 3.1.8
c
2016 ALPES LASERS SA

This page intentionally left blank.

COPYRIGHT INFORMATION
This manual can be copied and distributed under the following conditions: the work
must be attributed in the manner specified by the author or licensor, and cannot be
altered or transformed.
WARRANTY
1. The customer must control the incoming deliveries and inform ALPES LASERS
about incomplete shipments or defective goods within 30 days after delivery.
ALPES LASERS warrants that the products respect the performance set forth in
the quotation, provided that the product is used according to ALPES LASERS
recommendations described in the datasheet included in the shipment.
2. Defective products will be replaced during the 2 years following delivery.
3. All other claims such as purchase refund, product reconditioning or damage of
any nature, be it direct, indirect or consequential, are expressly ousted.
4. The customer is aware of laser products being devices with a statistical rate of
failure. Depending on the use made of this product, it is the customer’s respon-
sibility to use caution, redundancy and appropriate technical measurement to
ensure the final product’s proper operation.
5. In case of discrepancy between the manual and terms written in the order con-
firmation, the order confirmation prevails.
CONTACT INFORMATION
Avenue des Pâquiers 1
2072 St-Blaise
Switzerland
Telephone: [phone]
Fax: [phone]
Email: inf[email protected]
Web site: http://www.alpeslasers.ch
c
2016 SA iii

DOCUMENT VERSION
This is Version 3.1.8 of the manual, published on March 11th, 2016, superseding
version 3.1.7 of the manual, published on October 16th, 2015. The following modifi-
cations have been applied since the publication of version 3.0:
Date of publication Version number Changes
11/3/2016 3.1.7 Change of address
16/10/2015 3.1.7 Modified § 5.4 - removed TC-3 control comments
11/09/2015 3.1.6 Modified § 5.4 after software improvements
26/08/2015 3.1.5
Corrected fig. 5.8 and added informa-
tion on high duty cycle operation
07/08/2015 3.1.4 Added § 5.4
14/05/2014 3.1.3 Clarified Menu navigation in § 5.1.1
29/04/2013 3.1.2 Updated table 5.2
07/03/2013 3.1.1 Added §C.1
28/01/2013 3.1.0
§ 1.3.2 was added and § 1.3.1 is depre-
cated.
§3.3.7 and 3.3.8 have been added.
§5.1 has been added.
Various references to temperature con-
trollers have been updated throughout
the manual.
24/05/2012 3.0.1 § 1.3.3, the LDD voltage is typically be-
low the ratings, not above.
iv QCL user’s manual v3.1.8

Preface
This manual is a reference tool for personnel using ALPES LASERS QCLs and elec-
tronic equipment. Its purpose is to provide the customer with sufficient information to
carry out normal installation and operating procedures. It is not intended to replace
or supersede any local directive. Table 1 gives a summary of the content of each
chapter.
CAUTION:
All personnel must read and understand this manual before attempting
to operate ALPES LASERS QCLs or electronic device. Failure to follow
safety instructions could result in death or serious injury.
Chapter Content
1. Overview General overview of ALPES LASERS QCLs and Starter
Kit components.
2. Safety Information for ensuring safety during the installation, op-
eration and maintenance of ALPES LASERS QCLs and
electronic equipment.
3. Installation Prerequisites, guidelines and list of connections for the
installation of ALPES LASERS equipment.
4. QCL operation Principle of operation of QCLs, ALPES LASERS datasheet
and QCL parameters.
5. Starter Kit Operation Procedures for setting up the Starter Kit and operating a
QCL.
6. Technical specifications Technical specifications and drawings of ALPES LASERS
QCLs and electronic equipment.
7. Maintenance Procedures for exchanging a laser in the LLH housing
and calibrating ALPES LASERS electronic equipment.
Appendices Informations and procedures for advanced users.
Table 1.: Structure of the QCL User’s Manual.
v

Typesetting conventions
•Table 2 gives a list of the acronyms used in this manual.
•Aboxed item indicates a hardware setting on an electronic device.
!"
#$%
&'( )*+,-./-01,-
$'
2## 2*+,-.#03/,.#-01,-
224
5#"
567
5(
8&9
:72 :;*<=;>.7*+?*/,.2*+,-
(6
67@
6&7
6'A :72.B;)+,-.=0>0<C.;<0=
!?-3<D> 8EE0?0*).<*>, 8=F,-.<*>,
!<=0G",E),?=03<.?3*=0<C
#0+=-0H;=,/.$,,/%*?I.J)*+,-K
&L=,-<*).B3M,-.+;BB)D
$*H-DG',-3=.J)*+,-K
:72.B;)+,-.+M0=?F0<C.;<0=
2*H3-*=3-D.2*+,-.43;+0<C
5,C*=01,.#0EE,-,<=0*).",+0+=*<?,
5,C*=01,.6F,->*).73,EE0?0,<=
+?-,M,/.)*+,-.+;H>3;<=
8-0C0<*).&N;0B>,<=.9*<;E*?=;-,-
?)*>B,/.)*+,-.+;H>3;<=
6,> B ,- * =; -,. 7 3< =-3 ) .@< 0=
6F,->3&),?=-0?.733),- ',)=0,-.?33),-
662.';)+,.A,<,-*=3-
Table 2.: Acronyms used in this manual.
vi QCL user’s manual v3.1.8

Contents
Preface v
1. Overview 1
1.1. ALPES LASERS products . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.1. QCL parameters and performance . . . . . . . . . . . . . . . . 2
1.1.2. QCL geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.3. QCL mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. QCL housings and packages . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1. Laboratory Laser Housing (LLH) . . . . . . . . . . . . . . . . . 5
1.2.2. High Heat Load (HHL) Housing . . . . . . . . . . . . . . . . . . 6
1.2.3. TO3 Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3. Starter kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.1. Temperature Controller (TCU) . . . . . . . . . . . . . . . . . . 10
1.3.2. Temperature Controller (TC-3) . . . . . . . . . . . . . . . . . . 11
1.3.3. Laser Diode Driver (LDD) . . . . . . . . . . . . . . . . . . . . . 12
1.3.4. TTL Pulse Generator (TPG) . . . . . . . . . . . . . . . . . . . 14
1.3.5. S-2 QCL Pulser . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4. Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.5. Fields of applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.5.1. IR.................................. 16
1.5.2. THz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2. Safety 19
2.1. General safety considerations . . . . . . . . . . . . . . . . . . . . . . 20
2.2. Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.2.1. Symbols and labels . . . . . . . . . . . . . . . . . . . . . . . . 22
2.3. Health hazard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3.1. LASER radiation hazard . . . . . . . . . . . . . . . . . . . . . . 23
2.3.2. Electrical hazard . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3.3. Environmental hazard . . . . . . . . . . . . . . . . . . . . . . . 23
3. Installation 25
3.1. Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.1.1. Environmental conditions . . . . . . . . . . . . . . . . . . . . . 26
3.1.2. Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.2. Receiving procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
vii

3.3. Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.3.1. LLH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3.2. HHL ................................ 34
3.3.3. TO3 ................................ 35
3.3.4. LDD ................................ 36
3.3.5. CTL cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3.3.6. CTLm cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.3.7. TC-LLH cable . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3.8. TC-HHL cable . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3.9. CPL cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3.10. CIL cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.3.11. Connection procedure . . . . . . . . . . . . . . . . . . . . . . . 42
4. QCL Operation 45
4.1. Principle of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.2. ALPES LASERS datasheet . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.3. QCL spectra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.3.1. Temperature and current tuning . . . . . . . . . . . . . . . . . 48
4.3.2. Linewidth of pulsed single-mode DFB QCLs . . . . . . . . . . . 51
4.3.3. Linewidth of CW single-mode DFB QCLs . . . . . . . . . . . . 51
4.3.4. Bandwidth of multi-mode FP QCLs . . . . . . . . . . . . . . . . 52
4.4. I-V curve and emitted power . . . . . . . . . . . . . . . . . . . . . . . 52
4.4.1. Maximum operating current . . . . . . . . . . . . . . . . . . . . 54
4.4.2. Maximum LDD voltage . . . . . . . . . . . . . . . . . . . . . . 55
4.4.3. Other DFB QCL plots . . . . . . . . . . . . . . . . . . . . . . . 56
4.5. Beam Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5. Starter Kit Operation 59
5.1. Temperature Controller TC-3 . . . . . . . . . . . . . . . . . . . . . . . 60
5.1.1. Quick Start Procedure . . . . . . . . . . . . . . . . . . . . . . . 60
5.2. Temperature Controller Unit (TCU) . . . . . . . . . . . . . . . . . . . 63
5.2.1. TCU startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.2.2. Internal/external mode . . . . . . . . . . . . . . . . . . . . . . 65
5.2.3. TCU interlock . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.3. TTL Pulse Generator (TPG) . . . . . . . . . . . . . . . . . . . . . . . 67
5.3.1. Internal and external modes . . . . . . . . . . . . . . . . . . . 68
5.3.2. Setting the pulse parameters . . . . . . . . . . . . . . . . . . . 70
5.3.3. Maximum duty cycle . . . . . . . . . . . . . . . . . . . . . . . . 71
5.4. S-2 Pulser (S-2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.4.1. Internal Control . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.4.2. External Control . . . . . . . . . . . . . . . . . . . . . . . . . . 76
5.5. General procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.5.1. QCL startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.5.2. QCL shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
viii QCL user’s manual v3.1.8

6. Technical specifications 83
7. Maintenance 91
7.1. Laser installation in LLH housing . . . . . . . . . . . . . . . . . . . . . 92
7.1.1. Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
7.1.2. Contact set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7.1.3. Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7.1.4. UP and DN contact exchange . . . . . . . . . . . . . . . . . . 97
7.2. Calibration procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.2.1. TCU interlock level setting procedure . . . . . . . . . . . . . . 99
7.2.2. TCU calibration . . . . . . . . . . . . . . . . . . . . . . . . . . 100
7.2.3. TPG calibration . . . . . . . . . . . . . . . . . . . . . . . . . . 109
A. QCL theory and application notes 113
A.1. QCL wavelength range . . . . . . . . . . . . . . . . . . . . . . . . . . 113
A.2. QCL electrical response . . . . . . . . . . . . . . . . . . . . . . . . . 114
B. Operations for advanced users 115
B.1. Direct QCL voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
B.2. Soldering wire bonds from laser chip to submount . . . . . . . . . . . 116
B.3. Bias-T circuit for pulsed lasers . . . . . . . . . . . . . . . . . . . . . . 117
B.3.1. Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
B.3.2. Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
B.3.3. Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
B.3.4. Gas concentration measurement . . . . . . . . . . . . . . . . . 118
B.4. CW modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
B.4.1. External power supply protection . . . . . . . . . . . . . . . . . 120
C. Cryogenic operation of QCLs 123
C.1. LN2 Dewar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
C.1.1. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
C.1.2. Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
C.2. Others . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
c
2016 SA ix

This page intentionally left blank.

1. Overview
The following chapter gives a general overview ALPES LASERS lasers and equipment
is given, as well as a brief introduction to the detection principle and fields of applica-
tion of quantum cascade lasers (QCLs).
Contents
1.1. ALPES LASERS products . . . . . . . . . . . . . . . . . . . . 2
1.1.1. QCL parameters and performance . . . . . . . . . . . . . . . 2
1.1.2. QCL geometry . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.3. QCL mounting . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. QCL housings and packages . . . . . . . . . . . . . . . . . . 4
1.2.1. Laboratory Laser Housing (LLH) . . . . . . . . . . . . . . . . 5
1.2.2. High Heat Load (HHL) Housing . . . . . . . . . . . . . . . . . 6
1.2.3. TO3 Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3. Starter kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.1. Temperature Controller (TCU) . . . . . . . . . . . . . . . . . 10
1.3.2. Temperature Controller (TC-3) . . . . . . . . . . . . . . . . . 11
1.3.3. Laser Diode Driver (LDD) . . . . . . . . . . . . . . . . . . . . 12
1.3.4. TTL Pulse Generator (TPG) . . . . . . . . . . . . . . . . . . 14
1.3.5. S-2 QCL Pulser . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4. Peripherals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.5. Fields of applications . . . . . . . . . . . . . . . . . . . . . . 16
1.5.1. IR................................. 16
1.5.2. THz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1

Chapter 1: Overview
1.1. ALPES LASERS products
ALPES LASERS manufactures two types of Quantum Cascade Lasers (QCLs): sin-
glemode Distributed-Feedback (DFB) or multimode Fabry-Perot (FP), which can be
operated in two modes: continuous wave (CW) or pulsed. ALPES LASERS lasers are
available in different types of packaging, presented in section 1.2. ALPES LASERS
developed dedicated electronics to control the temperature and current drive of its
QCLs; see section 1.3 for details.
ALPES LASERS is constantly developing new QCLs and electronics to satisfy inquiries
from its customers. Contact ALPES LASERS to find the best solution for your application.
1.1.1. QCL parameters and performance
All ALPES LASERS lasers are thoroughly tested and characterized. The results are
reported in datasheets, which are readily available on ALPES LASERS website. Each
QCL is delivered with its datasheet, containing data on singlemode and multimode
emission, IV curves, emitted power, maximum operating current and operation tem-
perature. See section 4.2 for details.
1.1.2. QCL geometry
Figure 1.1 shows an ALPES LASERS QCL growth and a laser chip mounted on an NS
submount (see section 1.1.3). By convention, the vertical axis of the laser is parallel
to the growth direction, as well as the beam polarization (i.e. electric field) and the
NS submount screw holes axis. The emission axis is perpendicular to the growth
direction and to the edges of the NS submount.
Figure 1.1.: ALPES LASERS QCL growth (left) and laser chip mounted on a submount
(right).
The laser chip is soldered to a copper base and is bonded with gold bonds to two
AlN ceramic pads, which are also mounted on the same copper base, as shown in
2 QCL user’s manual v3.1.8

1.1 ALPES LASERS products
figure 1.2. The surface of the ceramic pads is covered with a gold layer and their sides
have a whitish ceramic color. The golden surface must be positioned upwards. When
looking into the LLH from the top, the pad left of the direction of emission is labeled
DN for down, and the right pad UP for up. Only one pad is characterized, as specified
in the datasheet. If only one pad is present, it is in the DN position by default.
Polarity
By default, the laser has negative polarity: the cathode is connected to the ceramic
pads and the anode is connected to the submount copper plate (see figure 1.2). The
laser may be mounted junction down; this is clearly indicated on the laser box. In
this case, the laser has positive polarity: the cathode is connected to the submount
copper plate and the anode to the ceramic pads.
1.1.3. QCL mounting
ALPES LASERS QCLs can be mounted on two types of submounts:
•ST: clamped mounting
•NS: screwed mounting
The QCL submount can be integrated in a LLH, HHL or in any package designed
by the customer. The QCL submount is mounted on a copper plate, which lies on a
Peltier junction for heat dissipation, as shown in figure 1.2.
3HOWLHUMXQFWLRQ
EDVHFRSSHUSODWH
VXEPRXQWFRSSHUSODWH
SDG
ODVHUFKLS
JROGZLUHERQGV
Figure 1.2.: ALPES LASERS QCL NS submount mounted in a HHL or LLH housing.
c
2016 SA 3

Chapter 1: Overview
1.2. QCL housings and packages
ALPES LASERS QCLs can be delivered in 5 kinds of packages:
Chip-on-Carrier (CoC) A laser chip available on stock is mounted on either a NS or
ST submount (see section 1.1.3) . These submounts can be integrated into a
LLH or HHL housing, or can be sold separately, to be integrated in a piece of
equipment manufactured by the customer.
Laboratory Laser Housing (LLH) The LLH is designed for research applications,
and can be cooled down to -30◦C with water cooling. This is the most ver-
satile housing unit available because LLH has an easy laser exchange and is
compatible with the Starter Kit. All ALPES LASERS available in stock can be
used in a LLH housing. See section 1.2.1 for details.
High Heat Load (HHL) The HHL housing is a sealed collimated housing with TEC
for CW or pulsed lasers. The optional collimating lens is protected by a plane
window, making it ideal for operating in aggressive environments. See section
1.2.2 for details.
TO3 Pulsed lasers are available in TO3 cans, which are smaller and less power-
intensive than the HHL packages. TO3 housings are sealed, include a TEC and
are available with AR coated lenses for beam collimation or flat windows. Their
small size and low dissipation (less than 4W in pulsed mode) make them ideal
for integrating the QCL into a piece of equipment manufactured by the customer.
Note: most lasers listed on ALPES LASERS website cannot be mounted in a
TO3 housing; address your inquiry directly to ALPES LASERS.
Bare Chips : untested laser chips
4 QCL user’s manual v3.1.8

1.2 QCL housings and packages
1.2.1. Laboratory Laser Housing (LLH)
The LLH consists of a housing unit that includes a TEC and encapsulates the QCL
chip; it is designed to ease its installation and replacement. Its internal temperature
is controlled by a Peltier junction and a PT-100 temperature sensor, and can reach
tempuratures of less than -30◦C. Heat should be dissipated using one of the setups
described in section 3.1.2. The LLH temperature is controlled by the TC-3 (see section
5.1).
Figure 1.3.: LLH housing.
Figure 1.4.: LLH housing connection panel and window.
c
2016 SA 5

Chapter 1: Overview
1.2.2. High Heat Load (HHL) Housing
The HHL housing is much smaller than the LLH and is completely sealed. The HHL
contains a Peltier junction and a PT-100 or NTC temperature sensor, which can be
controlled by the TC-3 (see section 5.1) or a local temperature control system. Heat
dissipation is performed by thermal contact with its copper base; the heat dissipation
capacity depends on the operation mode and environmental conditions. The IR beam
is collimated through a chalcogenide glass lens and goes through an AR-coated ZnSe
window.
Figure 1.5.: HHL housing.
6 QCL user’s manual v3.1.8

1.2 QCL housings and packages
1.2.3. TO3 Housing
The TO3 housing is a hermetically sealed small-footprint housing designed to be in-
tegrated into commercial devices. It is available in two versions: the TO3-W has a
divergent output through an AR coated window, and the TO3-L (shown in figure 1.6)
has a collimated output. The TO3 contains a TEC and a NTC temperature sensor.
The TEC power is limited compared to the TEC included in the HHL or LLH housing,
therefore only pulsed lasers can be encapsulated in TO3 housings.
Figure 1.6.: TO3-L housing.
Note: QCLs mounted on an NS submount and controllers of the Starter Kit (see
section 1.3) are not compatible with the TO3 housing, therefore encapsulation of a
QCL in a TO3 housing is performed upon specific request only.
c
2016 SA 7

Chapter 1: Overview
1.3. Starter kit
The purpose of the Starter Kit is to readily operate an ALPES LASERS QCL. The user
must provide an external power supply; see section 3.1 for prerequisites and section
1.4 for recommended peripherals. The kit includes all the necessary cables for the
LLH or HHL housing, electronic devices (TCU or TC-3, LDD and TPG for pulsed
operation), power cables and connections for optional water cooling. The installation
and connections of the Starter Kit components are described in chapter 3.
The photos in this chapter show the TCU temperature controller, but the Starter Kit
is delivered with the fully compatible TC-3 controller starting in 2013.
CW mode
The Starter Kit shown in figure 1.7 is meant to operate QCLs in CW mode. It consists
of the following elements, which are described in dedicated subsections:
•Temperature Controller Unit (TCU), section 1.3.1 or TC-3 Temperature Con-
troller, section 1.3.2.
•CIL and appropriate cable for laser driver and temperature controller, section
3.3
Figure 1.7.: Starter Kit for CW mode operation, shown with laser driver (not included
in the Starter Kit).
Note: a CW QCL is very sensitive to electrical surges and instabilities as with any
conventional bipolar laser diode (telecom NIR laser). It is necessary to use a good
quality power supply; see section 1.4 for recommended peripherals.
8 QCL user’s manual v3.1.8

1.3 Starter kit
Pulsed mode
The Starter Kit shown in figure 1.8 is meant to operate QCLs in pulsed mode. It
consists of the following elements, which are described in dedicated subsections:
•Temperature Controller Unit (TCU), section 1.3.1 or TC-3 Temperature Con-
troller, section 1.3.2.
•A S-2 pulser, section 1.3.5, or a kit consisting of a Laser Diode Driver (LDD),
section 1.3.3, a CPL cable and a TTL pulse generator (TPG), section 1.3.4
•All necessary cables for the approriate laser driver and temperature controller,
section 3.3
2
1
3
4
Figure 1.8.: Starter Kit TCU (2), LDD (3) and TPG (4) for operation in pulsed mode.
c
2016 SA 9

Chapter 1: Overview
1.3.1. Temperature Controller (TCU)
CAUTION:
The TCU unit was sold from 1998 until 2012. It was sold in two
different models, TCU151 and TCU200, with identical functionalities
and controls. It was superseded starting in 2013 with the TC-3 unit
described in § 1.3.2.
The purpose of the TCU is to control the laser temperature inside the LLH or HHL
housing. It powers the Peltier junction and reads the temperature from the PT100
sensor coupled to the laser chip (see section 1.2.1). The TCU internal parameters
are set in factory according to its use with a LLH or HHL housing. It maintains a
preset temperature using the front panel knobs (internal mode) or from a user supplied
voltage (external mode). It also provides an output for real temperature monitoring.
The TCU interlock system protects the laser from overheating; see section 5.2 for
TCU operation procedures.
Figure 1.9.: TCU front panel.
10 QCL user’s manual v3.1.8