THORLABS MX10A User manual
MX10A or MX40A
12.5 Gb/s Modulator Driver
40 Gb/s Modulator Driver
User Guide
MX10A, MX40A Modulator Driver
Rev B, October 5, 2017
Table of Contents
Chapter 1Warning Symbol Definitions..............................................................................................1
Chapter 2Safety....................................................................................................................................2
Chapter 3Introduction..........................................................................................................................4
3.1.Description.......................................................................................................................4
3.2.Intensity or Phase Modulators .......................................................................................4
3.3.Parts List ..........................................................................................................................4
3.4.Block Diagram .................................................................................................................5
3.5.Front and Rear Panel Overview .....................................................................................6
Chapter 4Quick Start Guide................................................................................................................7
4.1.Hardware Set-up..............................................................................................................7
4.2.Controls on the Home Page ...........................................................................................8
4.3.Controls in the Settings Pages ......................................................................................9
Chapter 5Operating Instructions.......................................................................................................10
5.1.The Modulator Transmission Function (Intensity Modulators Only)........................10
5.2.Control Loop Diagram ..................................................................................................10
5.3.Bias Settings Page (Intensity Modulators Only) ........................................................11
5.4.Amplifier Settings Page ................................................................................................17
5.5.Variable Optical Attenuator Settings Page .................................................................19
5.6.Load Page ......................................................................................................................20
5.7.Menu Page .....................................................................................................................21
Chapter 6Specifications.....................................................................................................................24
6.1.General System Specifications....................................................................................24
6.2.Power & Environmental Specifications.......................................................................24
6.3.Internal Control Specifications ....................................................................................24
6.4.Internal Amplifier Specifications .................................................................................25
Chapter 7General Purpose I/O, RS-232, and USB Connections...................................................26
Chapter 8Mechanical Drawings.........................................................................................................27
Chapter 9Maintenance, Repair & Fuses...........................................................................................28
9.1.Maintenance & Repair...................................................................................................28
9.2.Replacement Parts ........................................................................................................28
9.3.Replacing the Main Fuse ..............................................................................................29
Chapter 10Troubleshooting.................................................................................................................30
MX10A, MX40A Modulator Driver
TTN035544-D02
Chapter 11Regulatory...........................................................................................................................31
Chapter 12Declaration of Conformity.................................................................................................32
Chapter 13Thorlabs Worldwide Contacts..........................................................................................34
MX10A, MX40A Modulator Driver Chapter 1: Warning Symbol Definitions
Rev B, October 5, 2017 Page 1
Chapter 1 Warning Symbol Definitions
Below is a list of warning symbols you may encounter in this manual or on your device.
Symbol Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or Chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
Caution: Risk of Electric Shock
Caution: Hot Surface
Caution: Risk of Danger
Warning: Laser Radiation
Caution: Spinning Blades May Cause Harm
Caution: ESD Sensitive Component
MX10A, MX40A Modulator Driver
Page 2 TTN035544-D02
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.
SHOCK WARNING
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.
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 on instrument
maintenance).
Only use mains cable with sufficient current and voltage ratings for this instrument.
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.
EXPLOSION WARNING
The instrument must not be operated in explosion endangered environments.
LASER WARNING
Avoid Exposure – Radiation Emitted from apertures. Do not look into the laser aperture while the laser
is on. Injury to the eye may result.
Caution – Use of controls or adjustments or performance of procedures other than those specified
herein may result in hazardous radiation exposure.
MX10A, MX40A Modulator Driver Chapter 2: Safety
Rev B, October 5, 2017 Page 3
CAUTION
This product is not suitable for household room illumination.
Inputs and outputs must only be connected with shielded connection cables.
Only with written consent from Thorlabs may changes to single components be carried out or
components not supplied by Thorlabs be used.
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.
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).
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 and meets all requirements of the Canadian Interference
Causing Equipment Standard ICES-003 for digital apparatus. 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.
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.
ESD CAUTION
Caution – 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.
CAUTION
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.
MX10A, MX40A Modulator Driver
Page 4 TTN035544-D02
Chapter 3 Introduction
3.1. Description
Thorlabs' High-Speed LiNbO3 Modulator Drivers provide control for fiber-coupled, lithium-niobate, electro-optic
modulators. Depending on the model, each driver is compatible with modulators that can operate at up to speeds
of 12.5 Gb/s or 40 Gb/s. The drivers’ internal circuitry enables bias control with peak, null, and quadrature set
points. The drivers also include a series of power monitors at the laser input, modulator output, and final optical
output, as well as a variable optical attenuator, for fully automatic monitoring and control of optical power along
the entire optical path. The operational wavelength range extends from 1250 nm to 1610 nm (O- through L-band),
and the user may select from power calibration points at 1310 nm, 1550 nm, and 1590 nm using the touchscreen
interface.
The 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, for details.
The most recent firmware and remote control software tool can be downloaded by visiting
https://www.thorlabs.com/navigation.cfm?Guide_ID=2191 and entering the Item # into the search field.
Thorlabs’ technical support can provide up-to-date information on available firmware revisions and control
functions.
NOTE: This manual covers both the MX10A and MX40A models, as their architectures are very similar.
Differences are clearly noted in the following sections.
3.2. Intensity or Phase Modulators
These drivers can be used for either intensity or phase modulators. For intensity modulators, the unit provides a
full complement of biasing options, both manual and automatic.
However, in the case of phase modulators, the DC biasing circuitry is not needed as it performs no function. In
that case, the user is advised to simply leave the Bias Control functionality turned OFF. All other functions will
operate normally.
3.3. Parts List
Inspect the shipping container for damage. If the shipping container seems to be damaged, keep it until you have
inspected the contents and tested the unit mechanically and electrically. Verify that you have received the
following items within the package:
1. MX10A or MX40A Modulator Driver Main Unit
2. Power Cord According to Local Power Supply
3. 1.25 A, 250 VAC Fuse
4. USB Type A to Type B Cable, 6’ Long
MX10A, MX40A Modulator Driver Chapter 3: Introduction
Rev B, October 5, 2017 Page 5
3.4. Block Diagram
These instruments provide all the electronics and control circuitry to bias and drive high-speed, fiber-coupled,
intensity or phase modulators. The user supplies the laser source, the signal source, and the modulator of their
choice. The Laser In port uses PM fiber with light linearly polarized along the slow axis as shown on the front
panel. Maximum input power is 20 dBm (100 mW). 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 modulator Output, and Mon-3 is at the final Optical Output.
MX10A, MX40A Modulator Driver
Page 6 TTN035544-D02
3.5. Front and Rear Panel Overview
Feature Description MX10A MX40A
Front Panel
A Touchscreen Display - -
B Adjustment Knob - -
D Grounding Jack Banana Banana
E Laser Input PM FC/PC PM FC/PC
F Laser Output to Modulator PM FC/PC PM FC/PC
G Return from Modulator FC/PC FC/PC
H Optical Output FC/PC FC/PC
J Amplifier RF Output SMA 2.92 mm
K
Bias Output SMA SMA
L RF Input SMA 2.92 mm
M Standby Button - -
Back Panel
N I/O Port DB-15 DB-15
O Option Label - -
P RS-232 Port DB-9 DB-9
Q USB Port Type B Type B
S Power Connector - -
T Fuse Tray - -
U Power Switch - -
A B
D
M
E F G HJKL
N O P Q
S T U
MX10A, MX40A Modulator Driver Chapter 4: Quick Start Guide
Rev B, October 5, 2017 Page 7
Chapter 4 Quick Start Guide
ESD CAUTION
Caution – 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.
4.1. Hardware Set-up
For first use, plug the main power cable into the rear panel connector, and then plug the other end into an AC wall
receptacle. Flip the power switch on the rear panel to the ON (I) position. The unit will now be in the “Standby”
mode, and the front panel standby button should glow amber.
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 boot 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.
MX10A, MX40A Modulator Driver
Page 8 TTN035544-D02
4.2. Controls on the Home Page
The MX10A and MX40A can be fully controlled by using the resistive touchscreen display for all functions. You
can use a finger or a plastic stylus to make selections on the screen. 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.
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 power buttons turn green to indicate the function is ON, and turn red to indicate the function is disabled.
The central section is the main dashboard 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 can
be disabled when the laser power is low. In this case, buttons may be disabled and warnings indicators may
appear.
Power units (dBm or
mW) are set in the
VOA Settings page
Disabled
Functions
Low Power
Warnings
Green Dot
Stability Indicator
Blue button
Utility functions
Tap these buttons to turn
functions ON or OFF
Tap in these areas to
go to the related
Settings pages
MX10A, MX40A Modulator Driver Chapter 4: Quick Start Guide
Rev B, October 5, 2017 Page 9
4.3. Controls in the Settings Pages
The Settings pages all follow 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 to highlight it, and the controls for that parameter will be presented.
The lower section with amber letters displays selected values that are convenient to monitor on that 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 touch-screen controls.
Tap to select parameter
Yellow highlight will appear
Increase value
Decrease value
Change Step Size
Confirm new value
Cancel any changes
Monitor area
MIN / MAX warnings
indicate that the setting
limit for a particular
parameter has been
reached.
MX10A, MX40A Modulator Driver
Page 10 TTN035544-D02
Chapter 5 Operating Instructions
5.1. The Modulator Transmission Function (Intensity Modulators Only)
The intensity modulator (e.g. MZM) has a repetitive transmission function with applied voltage as can be seen in
the diagram below. In order for it 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.
The purpose of the Bias settings is to hold the modulator at one of these chosen points. 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.
5.2. Control Loop Diagram
The following diagram shows the control loops added to the block diagram. From this picture, 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.
MX10A, MX40A Modulator Driver Chapter 5: Operating Instructions
Rev B, October 5, 2017 Page 11
5.3. Bias Settings Page (Intensity Modulators Only)
To get to the Bias Settings page tap the Bias monitors pane on the Home page. The Bias page contains the
settings for controlling the modulator bias and operating modes. There are four modes for modulator bias control:
1) Quadrature, 2) Peak, 3) Null, and 4) Manual. The screen shot below is an example of how the bias settings
page opens up if the controller is in the Quadrature mode. The blue buttons enable switching between modes.
Active control of the modulator bias point is essential as the modulator is temperature sensitive and will drift over
time. The Quadrature, Peak, and Null modes use a dither tone as part of a lock-in control scheme to keep the
modulator 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 modulator bias.
The first time you turn on the modulator Bias control, the instrument will perform a calibration routine to determine
the approximate bias voltages required for the various modulator operating points. This allows the instrument to
quickly and effectively switch between Bias modes. 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.
.
Tap to turn Bias On/Off
Tap to Reset Modulator Bias
New set points will be stored
Tap to select Peak Mode
Tap to select Quadrature Mode
Tap to select Null Mode
Tap to select Manual Mode
MX10A, MX40A Modulator Driver
Page 12 TTN035544-D02
5.3.1. Quadrature Mode
Quadrature is the default mode and biases the modulator at the 50% point on the modulator transmission curve
(see figure). This is the recommended mode for digital signals such as On-Off-Keying (OOK) that require a high
extinction ratio. The screen-shot below shows the parameters that can be controlled in the Quadrature mode.
The bias control circuit uses an AC dither tone to stabilize the bias point of the modulator. The graphic below
shows how it works:
A small AC voltage is applied to the DC bias so that the optical output is also slightly modulated. Both the
amplitude and the frequency of AC dither tone can be selected by the user. The modulated optical output is
detected by a frequency and phase sensitive detector which can then interpret whether the DC bias is at the
correct level for the chosen set-point (Quad, Peak or Null). The DC bias voltage is then continuously adjusted to
maintain the correct set-point.
The frequency of the dither tone (under 10kHz) is usually well below the low frequency cut-off for the RF signal of
interest, so it does not interfere. The dither tone can also be turned if other methods of bias control are desired
(e.g. manual control, or input/output ratio control as described later).
Select your own Dither
Frequency here
Choose one of three preset
Dither Frequencies
MX10A, MX40A Modulator Driver Chapter 5: Operating Instructions
Rev B, October 5, 2017 Page 13
The dither tone frequency may be changed by tapping the Dither Frequency field. Standard frequencies are
available on the blue buttons, or a custom frequency may be chosen by pressing User Define. The dither tone
frequency usually has very little effect on the accuracy of the bias control, but in some cases a different frequency
may work better or be desirable depending on the RF signal applied, or the specific application. The User Define
button allows for the selection of an arbitrary frequency between 1 kHz and 10 kHz with 10 Hz resolution.
The dither tone amplitude can also be adjusted to any amplitude between 20 mV and 2 V with 1 mV resolution.
Higher amplitude will typically be more stable in the presence of modulator drift and broadband RF signals, but
larger dither tones also decrease SNR. If the amplitude is too low, the modulator bias may not stay locked.
Typically, a value between 300 mV and 500 mV is a good starting point.
In applications where the highest SNR is desired, there is also the option to disable the dither tone. This allows
the user to quickly turn the dither off, perform a measurement requiring low noise, and then turn the dither back
on. When the dither is turned off, the bias is simply held at the previous bias voltage. For longer term
measurements without dither, you can switch to Manual Mode and use a constant ratio method for stabilizing the
bias point. (See the Manual Mode section)
The Quadrature mode also allows the user to select between two operating points by selecting the Slope field.
Positive slope is the non-inverting operating point where increasing voltage on the modulator results in increasing
optical output power. Negative slope is the inverting operating point where increasing voltage on the modulator
results in decreasing optical output power. This effectively changes the phase of the response function.
Tap here to turn Dither On/Off
A
djust the Dither Amplitude
from this screen
Select Positive Slope
Select Negative Slope
Tap here to change Slope
MX10A, MX40A Modulator Driver
Page 14 TTN035544-D02
5.3.2. Peak Mode
The Peak Mode adjusts the DC bias voltage so the transmission is centered at a nearby transmission maximum.
In this mode only dither frequency and amplitude settings are available. These controls & settings are the same
as previously described for the Quadrature mode.
Peak and Null modes are often used to obtain phase modulation and non-linear frequency doubling. The optical
phase is 180° shifted on opposite sides of the Null point.
5.3.3. Null Mode
The Null Mode adjusts the DC bias voltage so the transmission is centered at a nearby transmission minimum. In
the Null mode only dither frequency and amplitude settings are available. These settings are the same as
previously described for the Quadrature mode.
Bias control in Peak mode;
Tap to change
Tap here to reset the Bias
calibration and return to
Peak mode.
Bias control in Null mode;
Tap to change
Tap here to reset the Bias
calibration and return to
Null mode.
MX10A, MX40A Modulator Driver Chapter 5: Operating Instructions
Rev B, October 5, 2017 Page 15
5.3.4. Manual Mode
The Manual mode allows the user to bias the modulator at any point of the transmission function desired. Manual
mode offers two modes of operation: 1) Constant Bias, and 2) Constant Ratio. In both of these modes, the dither
function is not active, and the controller uses different techniques to hold the bias steady.
Constant Bias is the most basic mode of operation and will apply a user selected DC voltage to the modulator.
This can be useful for performing brief measurements that only take a few minutes. During longer duration
experiments, the modulator is more likely to drift.
The Constant Ratio mode employs active control of the modulator bias, but without using a dither tone. As a
result, it can achieve superior SNR compared to the Quadrature mode. This mode is recommended for analog
signals or higher level Pulse-Amplitude Modulation (PAM) formats.
Constant Ratio works by holding the modulator ratio of input light (at Mon-1) to output light (at Mon-2) at a
constant value (typically at or close to Quadrature). Note that it does NOT take into account the insertion loss of
the modulator. Therefore, the user must have some knowledge of the IL between the Monitors. For example. If
the modulator has an IL of 3 dB, then the I/O ratio at maximum transmission is already 2:1. To bias the modulator
at the 50% point, the ratio must be doubled to 4:1. The modulator insertion loss is listed in the specifications.
Bias control in Manual mode;
Tap here to change mode.
Tap here to adjust Bias voltage.
Tap here to select Hold mode:
Constant Bias or Constant Ratio
Tap here to manually adjust the
modulator transmission ratio in
Constant Ratio mode.
This is the ratio of modulator input
power to output power.
MX10A, MX40A Modulator Driver
Page 16 TTN035544-D02
In the Constant Ratio mode there is an option to select between the two available operating regions by selecting
the Slope field. Positive slope is the non-inverting operating point where increasing voltage on the modulator
results in increasing optical output power. Negative slope is the inverting operating point where increasing voltage
on the modulator results in decreasing optical output power.
When switching to one of the Manual modes from a different bias mode, the Manual mode set point is
automatically calculated to keep the modulator at the same location on the transmission function. For example, in
order to switch to Constant Ratio mode at the Quadrature location, follow these steps:
Turn the bias on, and choose Quadrature mode.
Wait for the green indicator dot to stop blinking (indicating the bias is locked at quadrature)
Optional: For greater accuracy at this point, slowly reduce the dither tone amplitude to ~100 mV in order
to remove errors that can occur due to second order effects with a large dither tone. Make sure the green
dot is not blinking
Now change the bias mode to Manual and select Constant Ratio.
The instrument will calculate the ratio to keep the modulator biased at the Quadrature location.
From here, the ratio set point can be adjusted to further tune performance.
Select Positive Slope
Select Negative Slope
Tap here to Change Slope
MX10A, MX40A Modulator Driver Chapter 5: Operating Instructions
Rev B, October 5, 2017 Page 17
5.4. Amplifier Settings Page
To get to the Amplifier Settings page, tap on the Amplifier monitor pane on the Home page. The amplifier has a
fixed gain that it applies to a user input signal. The signal is then routed to the RF input port of the modulator via
the front panel loop-back cable.
There are two Modes for the amplifier: 1) Digital and 2) Analog, but both work with the same fixed gain. Analog
mode simply sets the output swing of the amplifier to maximum.
The default amplifier mode is Digital, in which case the output swing and crossing point can both be adjusted
while the gain is held constant. This digital mode is recommended for OOK (On-Off Keying) digital signals. The V
π
Swing button is provided to conveniently set the Max Output Swing to the optimum value to achieve high
extinction modulation with the internal modulator.
The Max Output Swing field allows the user to set the peak-to-peak output voltage of the amplifier, assuming the
amplifier input signal is large enough to cause the amplifier to start clipping. The Max Output Swing essentially
controls the output amplitude at which the amplifier starts clipping. When operating in the digital mode, it is
expected the user will supply a signal with sufficient input amplitude to cause the amplifier to clip.
Tap here to change modes.
Select Analog mode to
provide maximum output
swing
Select Digital mode to
enable adjustable
output swing
Tap here to adjust crossing set
point from -100 to +100
Tap here to adjust maximum
output swing in Digital mode
This manual suits for next models
1
Table of contents
Other THORLABS Modulator manuals
