iXBlue EOM User manual

Electro-Optical Modulators

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 2
Table of Contents
TABLE OF CONTENTS ......................................................................................................... 2
1HANDLING INSTRUCTIONS ............................................................................................ 3
1.1 UNPACKING STEPS .....................................................................................................................3
1.2 WARNINGS TO AVOID DAMAGE ...................................................................................................9
2INSTRUCTIONS BEFORE USE........................................................................................ 10
2.1 CLEANING ................................................................................................................................10
2.1 OPTICAL INTERFACES ...............................................................................................................10
2.1 ELECTRICAL INTERFACES ..........................................................................................................12
2.2 MAXIMUM RATINGS ..................................................................................................................14
3MEASUREMENT PARAMETERS .................................................................................... 15
3.1 INSERTION LOSS (IL)................................................................................................................15
3.2 STATIC EXTINCTION RATIO (SER) ............................................................................................18
3.3 HALF-WAVE VOLTAGE (V)AT LOW FREQUENCIES (KHZ)..........................................................20
3.4 RESIDUAL AMPLITUDE MODULATION (RAM) ...........................................................................22
3.5 POLARIZATION EXTINCTION RATIO (PER)................................................................................23
3.6 POLARIZATION DEPENDENT LOSS (PDL)..................................................................................25
3.7 ELECTRICAL RETURN LOSS S11 &ELECTRO-OPTICAL BANDWIDTH S21..........................................26

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 3
Handling instructions
1.1 Unpacking steps
1) Put the blister pack on a flat surface to open it:
Fig. 1
2) To open the blister pack either peel off or cut the orange label located on the front:
Fig. 2

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 4
Fig. 3
3) To open the blister pack, you can use the notches on the front:
Fig. 4

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 5
Fig. 5
4) Delicately remove the “do not pull here” labels and place them on another part of the blister
pack:
Fig. 6

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 6
Fig. 7
5) Remove the optical connectors and take the fibers out of their tray. Lift and hold the modulator
by its housing. Delicately pull it out, paying attention to the optical fibers: electrical pins and
RF connector.
Fig. 8

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 7
Fig. 9
Fig. 10

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 8
Fig. 11
Fig. 12

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 9
6) Remove the spring located on the DC pin:
Fig. 13
Fig. 13
7) Once the modulator is unpacked, you can use it.
•Remember to keep the blister pack if you need to store the modulator or send it back to us.
•To pack the modulator, repeat the previous unpacking steps from the end to the beginning. Do
not forget to put the short circuit on DC pins (spring).
1.2 Warnings to avoid damage
Never hold modulator:
a. by optical pigtails
b. by pins or RF connector
Fig. 14

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 10
Instructions before use
2.1 Cleaning
•We recommend manipulating the modulator with rubber gloves (or equivalent) and clean it
with alcohol-soaked optical paper (or equivalent).
•Check optical connectors cleanliness: any dust could damage the connectors or degrade the
optical parameters. Use specific wipes for cleaning optical connector, we recommend using
Whatman ® lens cleaning tissue, Grade 105, wetted with IPA.
•Clean RF connector with dry air before mating and use a torque wrench for tightening.
2.1 Optical interfaces
•Never pinch the fiber pigtail or apply instantaneous traction on it which could generate micro-
cracks in the fibre silica.
•Never bend or coil the fibre jacket under a radius of 30 mm.
Fig. 15
•Pay attention to fiber bends, particularly with the 2000 nm series where any small radius bend
could induce output optical power degradations.

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 11
•Check connectors compatibility:
Fig. 16
•Avoid any shock on the housing, the fiber jacket or the optical connectors.
•Because Lithium Niobate crystal is naturally birefringent, LiNbO3modulators are polarization
sensitive devices. The input light must be injected in the waveguide along a specific
orientation, as accurately as possible. Therefore a Single Mode –SM - and Polarization
Maintaining –PM - fiber is recommended at the input. If a SM fiber non PM is used, one must
use a polarization controller to obtain the desired light orientation at the input of the
modulator chip.
•Output Fiber: This will depend on your setup and the other components along the optical path.
There is generally no drawback in using a PM output fiber, even when reconnecting to a SM
fiber.
•Please also note that iXblue modulators:
-are birefringent when operating in the O Band, C Band and 2 µm (TE and TM modes
propagates with different properties).
-Are polarizing for all Near Infra-Red operation or when the option “-Pol” (embedded and in-
line polarizer) is selected for the O Band, C Band.

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 12
2.1 Electrical interfaces
The iXblue Photonics modulator comes with three kinds of electrical ports:
1) RF port: where the modulating signal is applied. Depending on the frequency range of
application, three kinds of RF/microwave connectors are used:
•2.92 mm / K type, female, compatible to mate with SMA/ 3.5 mm connectors.
•2.4 mm, female, compatible to mate with V / 1.85 mm connectors.
•1.85 mm / V type, female RF/microwave coaxial connector.
2) DC port: where a DC bias is applied to set the operating point of the intensity modulator.
The DC connectors are gold plated pins (0.76 mm).
3) Internal photodiode (PD) port: only used with intensity or IQ modulators. The connectors
are gold plated pins (0.76 mm).
Fig. 17
2.1.1 RF CONNECTOR
•RF inputs must be connected with SMA rigid coax. @ 0.8 Nm ≤ Torque ≤1.2 Nm
Fig. 18
RF
DC
PD

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 13
2.1.2 DC /INTERNAL PHOTODIODE PINS
Although the DC port has been tested using the J-ATD 002D standard - test G, care must be taken
when soldering the DC pins.
•For soldering gold-plated DC pins the use of a heat gun is not recommended as the excess heat
may cause some internal damage. If soldering is necessary, we recommend the use of a 0.5 to
0.8 mm diameter copper wire previously stripped and wrapped around the pin. Then solder the
wire to the pin with a 330°C to 350°C soldering iron equipped with a small clean soldering tip
and a 0.23 mm diameter tin wire.
•Alternatively, we can recommend a pin receptacle that is sized perfectly for a nice snug fit onto
those pins: PIN RECEPTACLE 0326 SERIES (Mill-Max Manufacturing Corp.). Accepted Diam. 0,56
mm –0,81 mm.
Fig. 19
2.1.3 INTERNAL PHOTODIODE PINS
•Take care to correctly connect the Anode / Cathode pins.

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 14
2.1.4 ELECTROSTATIC DISCHARGE (ESD)
Although the RF port has been tested Class 2 and the DC port Class 0 (MIL-STD-750E Method
1020.2), care must be taken to prevent ESD and other electrical stresses. Otherwise, delicate
electrical structures inside the package could be damaged.
•We recommend unpacking or packing EOM in an Electrostatic Protected Area (EPA).
•Applying a transient overvoltage or any voltage above the specified maximum may cause a
permanent damage to the modulator.
2.2Maximum ratings
•Check optical, electrical, environmental maximum ratings available on our website.
•We strongly recommend splicing the fibers and avoid optical connectors when operating at
high optical power levels (>100mW) and short wavelengths (1060 nm, 800 nm).

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 15
Measurement Parameters
This chapter describes the different set up used to measure each electrical or optical parameter of
the modulator.
3.1 Insertion Loss (IL)
The insertion loss is defined by the difference between the modulator’s input and output optical
power (dBm):
The following sections describe the measurement set up when the modulator comes with (W/) or
without (W/O) optical connectors.
3.1.1 W/ OPTICAL CONNECTORS
3.1.1.1 Reference measurement (Pref):
Fig. 20
3.1.1.2 Intensity EOM max transmission measurement (Pout):
Fig. 21
󰇛󰇜  󰇛󰇜 󰇛󰇜

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 16
3.1.1.3 Phase EOM transmission measurement (Pout):
Fig. 22
Note: This measurement includes an uncertainty attributed to the optical connector’s
misalignment and mating sleeve.
Depending on the quality/ compatibility of each optical element (connectors, mating sleeve), we
estimate that the excess optical losses are as following:
FC/APC @1550 nm: IL ≤0.25 dB per connector
FC/APC @1060 nm: IL ≤0.4 dB per connector
FC/APC @850 nm: IL ≤0.5 dB per connector.
3.1.2 W/O OPTICAL CONNECTORS (CUT-BACK METHOD)
The cut-back method is a well-known set up to avoid the uncertainty induced by optical
connectors. However, this method needs the use of a fiber fusion splicer equipment.
3.1.2.1 Reference measurement (Pref):
Fig. 23

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 17
3.1.2.2 Intensity EOM max transmission measurement (Pout):
Fig. 24
3.1.2.3 Phase EOM transmission measurement (Pout):
Fig. 25
Cut-back advantage: avoid uncertainty induced by optical connectors & mating sleeves (but still
includes splices losses, ≈ 0.01 dB per splice).

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 18
3.2 Static Extinction Ratio (SER)
The static extinction ratio is defined as the maximum dynamic between the optical ON-state and
OFF-state at the output of the intensity modulator:
Intensity Modulator Transfer Function
Fig. 26
3.2.1 EOM MAXIMUM TRANSMISSION MEASUREMENT (PMAX):
Pmax is set as reference on the powermeter
Fig. 27
󰇛󰇜  󰇛󰇜 󰇛󰇜

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 19
3.2.2 EOM MINIMUM TRANSMISSION MEASUREMENT (PMIN):
Fig. 28
Note: The DC voltage applied to adjust Pmin can be positive or negative. We recommend selecting
the voltage corresponding to Pmin that is closest to zero in order to minimize DC-drift.
Intensity Modulator Transfer Function
Fig. 29

EOMs Operating Manual
Ref. Ed. 0 –08/02/2021 20
3.3 Half-wave voltage (V) at low frequencies (kHz)
The half-wave voltage (V), is the voltage needed to induce a phase shift on the optical wave. With
the intensity modulator, which is a two-wave interferometer, it corresponds to the driving voltage
necessary to vary the optical output from the maximum of power to the minimum of power (see
the Modulator Transfer Function, MTF):
Intensity Modulator Transfer Function
Fig. 30
3.3.1 VDC MEASUREMENT SET UP (DC ELECTRICAL PORT)
Fig. 31