THORLABS MX110G Series User manual

MX110G Series
110 GHz E-O Converters
User Guide

Table of Contents
Chapter 1 Introduction ................................................................................................................. 1
Chapter 2 Safety........................................................................................................................... 5
Chapter 3 Quick Start Guide ......................................................................................................... 7
Chapter 4 Operating Instructions................................................................................................ 12
4.4.1 Quadrature Mode ............................................................................................................................................. 17
4.4.2 Peak Mode ........................................................................................................................................................ 17
4.4.3 Null Mode.......................................................................................................................................................... 19
4.4.4 Manual Mode.................................................................................................................................................... 19
4.8.1 Display and Sound Settings Page....................................................................................................................... 26
4.8.2 System Information Page .................................................................................................................................. 27
4.8.3 Accent LED Settings Page .................................................................................................................................. 27
4.8.4 Thorlabs Help Page............................................................................................................................................ 28
Chapter 5 Specifications ............................................................................................................. 29
5.4.1 Tunable Lasers................................................................................................................................................... 31

MX110G Series of E-O Converters
5.4.2 Fixed-Wavelength Lasers................................................................................................................................... 31
Chapter 6 Control and PC Connections ....................................................................................... 32
Chapter 7 Mechanical Drawings ................................................................................................. 35
Chapter 8 Maintenance, Repair, and Fuses................................................................................. 36
Chapter 9 Troubleshooting ......................................................................................................... 38
Chapter 10 Certifications and Compliance .................................................................................... 39
Chapter 11 Warranty and RMA Information................................................................................. 40
Chapter 12 Thorlabs Worldwide Contacts..................................................................................... 41

MX110G Series of E-O Converters Chapter 1: Introduction
Rev. A, June 8, 2023 Page 1
Chapter 1 Introduction
General Information
Thorlabs' MX110G Series of Electrical to Optical (E-O) Converters offers a frequency response up to 110 GHz. Each
converter incorporates a telecommunication-grade lithium niobate (LiNbO3) modulator that is stabilized by a fully
automatic bias controller. Select an internal tunable laser source, fixed-wavelength laser source, or couple an
external laser, operating from 1525 nm to 1575 nm for the MX110G and 1260 nm to 1360 nm for the
MX110G-1310, to the PM FC/PC fiber optic connector on the input panel. The instrument is fully driven using the
intuitive graphical user interface (GUI) touchscreen, and the RS-232 connection on the back panel enables remote
control of many instrument functions. Please contact Thorlabs Technical Support for up-to-date information on
the firmware revisions and control functions available.
These converters are particularly well suited for use as accessories that provide optical test capability for an all-
electrical vector network analyzer (VNA). This pairing enables an optical to electrical (O-E) device under test (DUT)
to be accurately measured. To support this use, each E-O converter ships with an *.s2p file characterizing its
frequency response. This frequency response can be used to de-embed the response of the O-E DUT by separating
the E-O converter’s response from the overall measurement response. Please see Section 4.2 for more
information.
This instrument can be controlled in two ways. The simplest method is directly via the built-in graphical user
interface (GUI) and touchscreen. The instrument can also be operated remotely via the RS-232 or USB ports on
the back panel. Remote control is enabled using simple SCPI-type serial commands from a PC. See the remote-
control user guide (RCUG), which can be downloaded from https://www.thorlabs.com/manuals.cfm.
The most recent firmware and remote-control software tool can be downloaded by visiting
https://www.thorlabs.com/software_pages/viewsoftwarepage.cfm?code=MX. Thorlabs’ technical support can
provide up-to-date information on available firmware revisions and control functions.
Parts List
Inspect the shipping container for damage. If the shipping container seems to be damaged, retain it until all
contents have been inspected and the unit has been mechanically and electrically tested. Verify receipt of the
following items:
•E-O Converter Main Unit
•Power Cord According to Local Power Supply
•PM Loopback Fiber Optical Cable
•Interlock Keys
•2.5 mm Interlock Pin (in Back Panel)
•1.25 A 250 VAC Fuse
•USB Type A to Type B Cable, 6' Long
•USB Storage Device with *.s2p File Characterizing Instrument

MX110G Series of E-O Converters Chapter 1: Introduction
Page 2 TTN311832-D02
Block Diagram
Each E-O converter is fully integrated and contains the laser source, lithium niobate (LiNbO3) Mach-Zehnder
intensity modulator (MZM), and automatic bias controller; the only required external input is the signal source to
the Modulator RF In port.
The MX110G converters include a C-band tunable laser and the MX110G-1310 converters include a 1310 nm fixed-
wavelength laser. The C-band laser sources are tunable on the ITU 50 GHz grid and include a dither feature for
wavelength stabilization.
Optical power is monitored in three places (Mon-1,-2,-3) for the purpose of enabling bias and power control.
These power values are also available at the I/O port. Mon-1 is at the Laser Input, Mon-2 is at the MZM Output,
and Mon-3 is at the final Optical Output.
An external laser source, operating from 1525 nm to 1575 nm for the MX110G or 1260 nm to 1360 nm for the
MX110G-1310, can also be used to provide the optical input. Either the internal laser or an external laser source
may be coupled to the Laser In port, which uses PM fiber with light linearly polarized along the slow axis, as shown
on the front panel. The maximum input power to the Laser In port is 17 dBm (50 mW).
Figure 1 Key Components of MX110G Series E-O Converters

MX110G Series of E-O Converters Chapter 1: Introduction
Rev. A, June 8, 2023 Page 3
Front and Back Panel Overview
Figure 2 Front Panel
Callout
Description
F1
Touchscreen Display
F2
Adjustment Knob
F3
Key Switch and Indicator
Lasing Disabled; Lasing Enabled
F4
Grounding Jack (Banana Connector)
Earth Ground
F5
Laser Output (PM FC/PC Connector)
F6
Laser Input (PM FC/PC Connector)
F7
Optical Output (FC/PC Connector)
F8
Modulator RF Input (1.0 mm Connector)
F9
Standby Button
F3
F4
F9
F7
F8
F1
F2
F5
F6

MX110G Series of E-O Converters Chapter 1: Introduction
Page 4 TTN311832-D02
Figure 3 Back Panel
Callout
Description
B1
I/O Port (DB15 Connector)
B2
Laser Interlock (2.5 mm Connector)
B3
Option Label
B4
RS232 Port (DB9 Connector)
B5
USB Port (USB Type B Connector)
B6
Power Connector
B7
Fuse Tray
B8
Power Switch
Supply On; Supply Off
B5
B3
B7
B4
B1
B2
B6
B8

MX110G Series of E-O Converters Chapter 2: Safety
Rev. A, June 8, 2023 Page 5
Chapter 2 Safety
All statements regarding safety of operation and technical data in this instruction manual will only apply when the
unit is operated correctly. If equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired. Only with written consent from Thorlabs may changes to single
components be carried out or components not supplied by Thorlabs be used.
Warning: Risk of Electrical Shock
Before applying power to the instrument, make sure that the protective conductor of the 3
conductor mains power cord is correctly connected to the protective earth contact of the socket
outlet. Improper grounding can cause electric shock with damage to your health or even death.
Only use mains cable with sufficient current and voltage ratings for this instrument. The local
supply voltage must be in the range specified on the rear panel, and the correct fuse must be
installed in the fuse holder. If not, please replace the main fuse (see Section 8.3). Do not position
equipment in a way that makes it difficult for the user to operate the disconnecting device. Do
not remove covers. Refer servicing to qualified personnel.
Warning: Risk of Explosion
The instrument must not be operated in explosion endangered environments.
Warning: Laser Radiation
Avoid Exposure –Radiation emitted from apertures. Do not
look into the laser aperture while the laser is on. Injury to the
eye may result. Laser should not be turned on unless there is an
optical fiber connected to the laser output port.
Caution –Use of controls or adjustments or performance of
procedures other than those specified herein may result in
hazardous radiation exposure.
Caution: ESD Sensitive Component
The components inside this instrument are ESD sensitive. Take all appropriate precautions to
discharge personnel and equipment before making any connections to the unit. A front panel
grounding jack is provided for connection to a wrist strap.

MX110G Series of E-O Converters Chapter 2: Safety
Page 6 TTN311832-D02
Caution: Components not Water Resistant
This instrument should be kept clear of environments where liquid spills or condensing
moisture are likely. It is not water resistant. To avoid damage to the instrument, do not expose
it to spray, liquids, or solvents.
Caution: Follow Intended Usage Guidelines
This product is not suitable for household room illumination.
Inputs and outputs must only be connected with shielded connection cables.
Do not obstruct the air ventilation slots in housing.
Mobile telephones, cellular phones or other radio transmitters are not to be used within the
range of three meters of this unit since the electromagnetic field intensity may then exceed
the maximum allowed disturbance values according to IEC 61326-1.
Precautions
The following statement applies to the products covered in this manual, unless otherwise specified herein. The
statement for other products will appear in the accompanying documentation.
Note: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to
part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference
in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instructions, may cause harmful interference to radio communications.
However, there is no guarantee that interference will not occur in a particular installation.
This product has been tested and found to comply with the limits according to IEC 61326-1 for using connection
cables shorter than 3 meters (9.8 feet).
Thorlabs is not responsible for any radio television interference caused by modifications of this equipment or the
substitution or attachment of connecting cables and equipment other than those specified by Thorlabs. The
correction of interference caused by such unauthorized modification, substitution or attachment will be the
responsibility of the user. The use of shielded I/O cables is required when connecting this equipment to any and
all optional peripheral or host devices. Failure to do so may violate FCC and ICES rules.
This precision device should only be shipped if packed into the complete original packaging including the custom
cut foam padding. If necessary, ask for replacement packing material.

MX110G Series of E-O Converters Chapter 3: Quick Start Guide
Rev. A, June 8, 2023 Page 7
Chapter 3 Quick Start Guide
Hardware Set Up
1. For first use, plug the main power cable into the back panel connector, and then plug the other end into
an AC wall receptacle.
2. Flip the power switch on the back panel to the ON (I) position. The unit will now be in the “Standby” mode,
and the front panel standby button should glow amber.
Figure 4 Power Cable Port, Fuse, and Power
Switch
Figure 5 Indicator Glows Amber When Instrument
Is in Standby
3. Attach the PM loop-back fiber optic cable between the LASER OUT and LASER IN FC connectors on the
front panel. Be sure to clean both ends of the fiber as described in the Maintenance Section of this manual.
Figure 6 PM Loopback Fiber Cable Installed
4. Insert the key into the interlock switch and turn it towards the unlock symbol ( ). This allows the laser to
be turned on, but the LASER ON indicator will not glow green until the laser is actually turned on by the
touchscreen button.
5. Turn on the unit by pressing the amber standby button on the front panel which will then turn green to
indicate the unit is fully on. The touchscreen display will come up with a splash screen for about 5 seconds
and then go to the home page. The unit will initialize in the factory default state with all functions OFF.
Figure 7 Interlock Key Switch
Figure 8 Indicator Glows Green When Instrument
is Fully Enabled

MX110G Series of E-O Converters Chapter 3: Quick Start Guide
Page 8 TTN311832-D02
Controls on the Home Page
Full access to all of the converter's controls and functions is available using the resistive touchscreen display, which
is sensitive to finger pressure or the tap of a plastic stylus. In addition, the knob on the front panel can be used in
place of the on-screen arrow buttons for quickly changing set-point values. Pressing (clicking) the knob will confirm
a new set-point value.
Figure 9 Home Screen Features
The Home screen (or dashboard) is organized into three main sections.
The left side contains the ON/OFF buttons for each of the main instrument functions. Tapping any of these buttons
will toggle the function on and off. The same ON/OFF functionality is also available on the individual Settings
pages. The function button turns green to indicate the function is ON and turns red to indicate the function is
disabled.
The center section on the main dashboard is for reporting operational values of each section. Tapping the screen
in this middle area will take the user to the corresponding Settings page for each section. Note that the green dot
in each of these sections indicates the function is stable. A blinking green dot indicates the function is still
stabilizing.
The right side of the screen provides access to the main utility functions of the box.
The screen shot below shows some of the common warning indicators on the HOME page. Some functions may
be disabled when the laser input power is low. In this case, function buttons will be disabled and warnings
indicators will appear.
Figure 10 Home Screen Warnings and Indicators
Blue Buttons:
Utility Functions
Tap in these areas
to go the related
Settings pages.
Green Dot Stability
Indicator Flashes or
is Solid
Power units (dBm or
mW) are set in the
VOA Settings page.
Tap these buttons
to turn function
ON or OFF.
Disabled
Functions
Low Power
Warnings
Interlock
Warning

MX110G Series of E-O Converters Chapter 3: Quick Start Guide
Rev. A, June 8, 2023 Page 9
Controls on the Settings Pages
The Settings pages all possess the same general design and functionality as shown in the example screen shot
below. The upper section with white letters displays the parameters that can be changed. Simply tap on the
parameter of interest. A yellow border highlights the choice and controls for that parameter are presented.
The lower section with amber letters displays selected related values convenient to monitor from the page.
The right-hand column provides the controls for changing the values for the selected parameters. The main control
knob on the front panel can also be used to adjust and confirm selected values. The screen shots below show
examples of the touchscreen controls.
Figure 11 Setting Parameter Values: Design and Functionality of the Settings Pages
Fields that have adjustable values will show a flag if the minimum or maximum values have been reached. These
are set by firmware at the factory.
Figure 12 MAX and MIN Warnings Indicate Parameter’s Upper or Lower Setting Limit Reached
Tap parameter to select it. Yellow
border highlights choice.
Increase value by tapping.
Decrease value by tapping.
Change step size by tapping.
Confirm new value by tapping.
Cancel any changes by tapping.
Monitor Area
MIN/MAX warnings
indicate that the setting
limit for a particular
parameter has been
reached.

MX110G Series of E-O Converters Chapter 3: Quick Start Guide
Page 10 TTN311832-D02
Quick Start
The following steps summarize the setup procedure required to operate the converter in the standard mode.
Please refer to previous sections in this chapter and the expanded operating instructions in Chapter 4 for
additional information.
1. Turn on power to the converter via the power switch on the back panel (Figure 4).
1. Press and hold the standby button on the front panel until the indicator light changes from amber to green
(Figure 5 and Figure 8).
2. Turn the key switch to unlock (Figure 7).
3. Turn the laser on by tapping the lower-left touchscreen button on the Home page (Figure 9).
a. Lower-left touchscreen button changing from grey to green indicates Laser On command has been
received.
b. Front panel LASER ON indicator illuminates green to indicate the laser has power and is on.
c. Flashing green dot above laser wavelength in Laser section on the Home page indicates the laser
is stabilizing (i.e. not yet settled at optical power/frequency setpoint). Solid green dot indicates
that the laser is stable.
4. Enable the bias controller by tapping the top-left touchscreen button on the Home page (Figure 9). Wait
for completion of the calibration process. The instrument will enable the default Quadrature mode with
positive slope bias point (Section 4.4).
5. Take note of the output power, which is shown in the center right section of the Home page (Figure 9).
6. Turn on the VOA controller to adjust output power, if desired, by tapping the center-left touchscreen
button on the Home page (Figure 9 and Section 4.5).
7. Apply the input RF signal to the female 1.0 mm connector on the front panel (Figure 2) noting the specified
limits for a linear response (Chapter 5).
a. Note this is a very sensitive input directly to the 110 GHz modulator. Be very careful with this
connector.
i. Be sure the input cable is discharged before attaching it to the connector.
ii. Do not overtighten the connection. Tighten using a standard W-connector 4 lb-in torque
wrench.
iii. Make sure the cable is properly supported to avoid any stress on the connector.
iv. Observe the maximum input voltage listed in (Chapter 5).

MX110G Series of E-O Converters Chapter 3: Quick Start Guide
Rev. A, June 8, 2023 Page 11
Figure 13 The MX110G E-O Converter
Safe Shutdown
The following steps summarize the shutdown procedure required to provide a controlled, internal power-down
sequence for the electronics, particularly when shutting down from a state when modulator bias is enabled.
1. If modulator bias is off, skip to step 4.
2. Turn modulator bias off by pressing the button on the touchscreen display.
3. A status message and status bar will appear on the screen indicating that the modulator bias voltage is
ramping down (Figure 14). DO NOT proceed until this message leaves the screen.
4. Press the standby button on the front panel until the indicator light changes from green to amber and the
screen turns off.
5. Switch off the main power on the back panel.
Figure 14 Bias Voltage Ramping Down Status Message

MX110G Series of E-O Converters Chapter 4: Operating Instructions
Page 12 TTN311832-D02
Chapter 4 Operating Instructions
The Modulator Transmission Function
The Mach-Zehnder modulator (MZM) has a repetitive transmission function with applied voltage as can be seen
in the diagram below. For the MZM to work correctly, a DC bias voltage must be applied and maintained at the
desired set point. The high-frequency AC signal can then be applied to the modulator to enable the correct optical
modulation of the laser beam. The most common operating points are the peak, null, and quadrature points as
shown below.
Figure 15 Bias Points on the Modulator Transmission Function
Note that a real transmission function does not go perfectly from 0% to 100%. This is characterized by the
Extinction Ratio of the modulator (Peak power / Null power). The efficiency of the modulator is also characterized
by Vπ, which is defined as the voltage necessary to change the transmission from Null to Peak. The most linear
response of the modulator is achieved by biasing it at one of the Quadrature points where the transmission is
closest to 50%. Some non-linear, frequency doubling, and phase modulation applications require biasing at the
Null or Peak.
0.5
0
1
V
Null
Peak
Quad-
Quad+
Quad-
Null
Modulator Transmission Function
Transmission
Applied Voltage
Peak

MX110G Series of E-O Converters Chapter 4: Operating Instructions
Rev. A, June 8, 2023 Page 13
The purpose of the Bias settings (Section 4.4) is to hold the modulator at the chosen operation point. Active control
of the MZM bias point is essential, as the modulator is temperature sensitive and will drift over time. Without
active control, the optimal bias point for a linear response can drift, causing non-linear artifacts and frequency
doubling to appear in the optical output.
Figure 16 (Left) The linear response observed when MZM is biased at the optimal positive quadrature
point. (Right) Without active control, the thermal shift in the MZM transmission function results in a
non-linear response.
The Peak and Null modes use a dither tone as part of a lock-in control scheme to keep the MZM bias stable. The
dither tone allows the control algorithm to track the drifting, but at the cost of decreased signal-to-noise ratio
(SNR) due to the injection of a single frequency tone into the MZM bias.

MX110G Series of E-O Converters Chapter 4: Operating Instructions
Page 14 TTN311832-D02
De-Embedding Procedures
One of the primary applications of a calibrated electrical to optical (E-O) converter is enabling electrical to
electrical (E-E) test equipment, like a VNA, to characterize optical to electrical (O-E) devices. As illustrated in Figure
20, the device converts the electrical signal from Port 1 of the E-E VNA to an optical signal that is input into the O-
E DUT, and the electrical signal resulting from the O-E DUT is then provided to Port 2 of the E-E test equipment.
The response of the entire E-E system, which consists of the converter and the O-E DUT together, is measured.
Accurately recovering the response of the O-E DUT requires removing the response of the converter from the
measured E-E system response. This is referred to as de-embedding.
Figure 17 An E-O Converter Provides Optical Test Capability for an All-Electrical VNA
Thorlabs provides a file (.s2p format) with each E-O converter that contains the S21 magnitude and phase
response of the modulator across its frequency range of operation. These data are used to perform the de-
embedding process. Note that most modern E-E VNA systems provide a built-in function for doing this type of
de-embedding based on the user-supplied .s2p file. This is the easiest method. However, the de-embedding
process can also be performed manually. These methods are described in detail in the "De-Embed Application
Note" PDF document, which is accessible by visiting www.thorlabs.com/manuals and entering the item # of
your E-O Converter.
A typical frequency response for each converter is plotted below in Figure 18. The phase response is not shown.
Figure 18 MX110G Series Typical Frequency Response

MX110G Series of E-O Converters Chapter 4: Operating Instructions
Rev. A, June 8, 2023 Page 15
Control Loop Diagram
The following diagram shows the control loops added to the block diagram. From this diagram, the user can see
how the power monitors and VOA are used to provide stability and control to the whole system. It will be helpful
to refer to this diagram to gain a better understanding of the functionality of the unit as described in the upcoming
sections of the manual.
Figure 19 Block Diagram of the MX110G Converter Showing Control Loops

MX110G Series of E-O Converters Chapter 4: Operating Instructions
Page 16 TTN311832-D02
Bias Settings Page
The Bias Settings page is accessed by tapping the center bias monitors pane on the Home page. When the MZM
Bias control is first turned on, the MX110G converter performs a calibration routine to determine the approximate
bias voltages required for the various MZM operating points. This allows the instrument to switch between bias
modes quickly and effectively. The user may perform this calibration anytime by pressing the Reset Auto Bias
button on the right side of the Bias Settings page. This button is not available if the Bias is off or in Manual mode.
Note that during calibration routines, changing bias modes, and briefly after enabling/disabling bias (i.e. any time
the bias voltage setpoint is under automatic control), the VOA in the instrument is configured for maximum
attenuation to protect a downstream optical component from inadvertent optical overload during the bias
transition sweep. ‘Attenuation protection measures’ are not active when bias is disabled or in Manual Bias mode.
Figure 20 Bias Settings Home Screen
The Bias Settings page contains the settings for controlling the modulator bias and operating modes. There are
four modes for MZM bias control: 1) Quadrature, 2) Peak, 3) Null, and 4) Manual. The screen shot in Figure 21 is
an example of the information presented and the controls available when the Mode field is selected while the
controller is operating in Quadrature mode. The blue buttons enable switching between modes.
Figure 21 Bias Settings Screen to Select Operating Mode
Note that on MX110G series converters, two bias voltages are displayed on the Bias Settings pages: Bias Voltage
V1 and Bias Voltage V2. The modulators internal to MX110G instruments have two DC bias ports for controlling a
thermo-optic phase shifter in each arm of the MZM. Bias Voltage V1 and Bias Voltage V2 are controlled
synchronously to maintain the desired operating point.
Tap to Turn Bias On/Off
Tap to reset modulator bias and to
store new set points in memory.
Tap to select Peak Mode.
Tap to select Quadrature Mode.
Tap to select Null Mode.
Tap to select Manual Mode.