LDX
3620B
Ultra Low Noise
Laser Diode
Current Source

Specifications
GENERAL

DRIVE CURRENT OUTPUT1
Output Current Range:
0 to 200 mA
Compliance Voltage:
5V
Temperature Coefficient:< 20 ppm / oC
2
Short Term Stability:
5 minutes:< 4 ppm
30 mintues:< 10 ppm
1 hour:< 10 ppm
2< 50 ppm
Long Term Stability (12 hours):
Noise and Ripple (rms):3
Charge Mode Operation
Low Bandwidth Mode (100 Hz): < 2.5 A
Low Bandwidth Mode (100 KHz): < 4.5 AHigh Bandwidth Mode (100 KHz): < 6 A
High Bandwidth Mode (1 MHz): < 7 A
Battery Operation
Low Bandwidth Mode (100 Hz): < 70 nA
Low Bandwidth Mode (100 KHz): < 200 nA
High Bandwidth Mode (100 KHz): < 500 nA
High Bandwidth Mode (1 MHz): < 750 nA
Transients: 4
Operational (output on/off):< 10 A
Operational (power on/off):< 1mA

0 to 500 mA
5V< 20 ppm / oC
< 4 ppm< 10 ppm< 10 ppm< 50 ppm< 2.5 A
< 4.5 A
< 7 A< 8 A< 120 nA
< 400 nA
< 900 nA
< 2 A< 10 A< 1 mA

DRIVE CURRENT LIMIT SETTINGS
Range:
Accuracy (% of FS):

10 to 500 mA+5 mA

DC Input Power Requirements:
Maximum Current Draw
100VAC to 120VAC:
220VAC to 240VAC:
Batteries
Battery Operation Time:7
Battery Charge Time:+12V Supply
Type:
Capacity:
Charge Operating Temperature:
Discharge Operating Temperature:
Weight:-12V Supply
Type:
Capacity:
Weight:Size (HxWxD):
Weight:Operating Temperature:
Storage Temperature:
Humidity:
Regulatory Compliance:

PHOTODIODE FEEDBACKType:PD Current Input Range:

Differential
20 to 2000.0 µA

Differential
20 to 2000.0 µA

EXTERNAL ANALOG MODULATION
Input 1:
Transfer Function:
Bandwidth (3dB; DC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Bandwidth (3dB; AC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Input Impedance:
Input 2:
Transfer Function:
Bandwidth (3dB; DC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Bandwidth (3dB; AC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Input Impedance:

10V
20 mA/V

10V
50 mA/V

DC to 1 MHz
10 kHzDC to 1 MHz
10 kHz100 Hz to 1 MHz
100 Hz to 10 kHz
1 K
10V
2 mA/V

100 Hz to 1 MHz
100 Hz to 10 kHz
1 K
10V
5 mA/VDC to 1 MHz
10 kHzDC to 1 MHz
10 kHz100 Hz to 1 MHz
100 Hz to 10 kHz
1 K

100 Hz to 1 MHz
100 Hz to 10 kHz
1 K

0 to 199.99 mA
0.01 mA
0.1% FS
0 to 1999.9 µA
0.1 µA+2 µA

0 to 500.0 mA
0.1 mA
0.2% FS
0 to 1999.9 µA
0.1 µA+2 µA

MEASUREMENT
Output Current Range:
Output Current Resolution:
Output Current Accuracy:
Photodiode Current Range:
Photodiode Current Resolution:
Photodiode Current Accuracy:

INPUT/OUTPUT CONNECTORS
Photodiode:
Modulation (Input 1):
Modulation (Input 2):
Laser Current Source:
DC Power Supply:

100VAC - 120VAC +10%, 47 to 63 Hz
220VAC - 230VAC +10%, 47 to 63 Hz

Product Features

1.6A
1.6A
16 hours
15 hours

Battery operated dual range
200mA/500 mA current source

Lead acid12 amp-hour
0 - 40oC-20oC - 50oC
3.94 kg (8.68 lbs)

<100 nA rms noise in battery mode

Lead acid
2.2 amp-hour
0.94 kg (2.07 lbs)
5” x 13.4” x 16.3”
127mm x 340mm x 414mm
25.4 lbs.; 11.11 kg
0oC to 40oC
-40oC to 60oC
Up to 80%, non-condensing
CE Certified; EMC Directive 2004/108/
EC per standard EN61326-1:2006;
Low Voltage Directive 2006/96/EC per
standard EN61010-1:2001

Better than 10ppm stability over
one hourConstant current and constant power
operating modes
Laser diode protection and error
detection circuits protect lasers in all
operating modes

NOTES

1. Unless otherwise noted, all specifications measured at 23oC + 3oC after a
one hour warm up period.
2. Over the specified period, half-scale output into a temperature controlled
resistive load.
3. Measured electrically, with a 24 load evaluating AC coupled rms value
over the specified bandwidth.
4. Maximum output current transient resulting from normal operationalsituations (e.g. power on-off, current on-off) as well as accidental situations(e.g. power line plug removal).
5. Reserved.
6. Sine wave with 5V peak to peak modulation at half scale output.
7. Battery operating time is the same for both 200 mA and 500 mA ranges;
instrument circuitry draws 500 mA in either current range.

ORDERING INFORMATION
LDX-3620B
LDX-362038
CC-305S
CC-306S
LDM-4412
LDM-4405
LDM-4407
LDM-4982
LDM-4984

Ultra Low Noise Current Source
Extra Battery Option
Current Source/LD Mount Interconnect Cable
Current Source Unterminated Interconnect Cable
Temperature Controlled TO-can Laser Diode Mountwith Collimating Lens
Low Cost TO-Can Laser Diode Mount
Temperature Controlled TO-can Laser Diode Mount
DIL Laser Diode Mount
Butterfly Laser Diode Mount

Two modulation inputs with up to 1MHz
bandwidth for precise laser tuning
Battery charge mode with front panel
charge level indication

The LDX-3620B is a battery powered, ultra low noise current
source, optimized for narrow linewidth or stable wavelength
laser diode applications. The all new instrument provides aprecision current output with <100 nA rms noise and <10ppm
stability. The current source can be operated in one of two output
ranges in constant current or constant power operating modes.
Additionally, two AC or DC coupled modulation inputs, fine andcoarse, can control the current source for precise laser diodewavelength or linewidth tuning with a bandwidth up to a 1 MHz.
All of ILX Lightwave’s proven laser diode protection features
are designed into each model, which include adjustable current
limits, a floating output, shoring relays, slow turn-on circuits, andtransient protection during power up and laser operation. Error
indicators help resolve set up problems quickly such as open
circuit and power limits.
Additional features include long battery life between charges,
a battery charge mode and front panel charge indicator making
the LDX-3620B a reliable test instrument for low noise, precisionlaser wavelength control applications. The LDX-3620B is
compatible with a large selection of ILX Lightwave laser
diode TO-can, butterfly, and DIL laser mounting fixtures withinterconnect cables for fast, easy system set up.

Other laser diode mounts are available; contact sales@ilxlightwave.com
for more information.
In keeping with our commitment to continuing improvement, ILX Lightwave reserves the right to change
specifications without notice or liability for such changes.

9-pin d-sub rear panel; BNC, rear panel
BNC, front panel
BNC, front panel
9-pin d-sub rear panelStandard Type RIB: DIN 5-pin

Battery Powered Ultra Low Noise
Laser Diode Current Source
For information call
P.O. Box 6310, Bozeman, MT 59771 • FAX: 406-586-9405

www.ilxlightwave.com

1-800-459-9459
International Inquiries: 406-556-2481
email: sales@ilxlightwave.com

Rev02.102010

LDX
3620B
Ultra Low Noise
Laser Diode
Current SourceUltra Low Noise
Laser Diode
Current Source

LDX
3620B

ULTRA LOW NOISE AND HIGHSTABILITY
A lead acid battery and careful design and attention todetail in component selection, instrument and circuitboard design allow the LDX-3620B to achieve an orderof magnitude lower noise levels than AC powered
current sources.
With proper cabling and laser diode mounting,current noise levels of <100 nA can be achieved;
critical performance for spectroscopic, coherent
communications, and other applications requiring
narrow linewidths.
The same attention to detail also allows the LDX-3620B
to achieve current source stability on the order of 10ppm
over any one hour period in any instrument mode ofoperation.

as a differential input allowing the control voltage andthe instrument’s laser output to use different grounds.
The constant power mode maintains constant opticaloperation of the laser diode by measuring thephotocurrent from the diode’s rear-facet photodiode,or from an external photodiode in a feedback control
loop to the current source. Coarse and fine gain
adjustments on the front panel are provided to scale
the display to the full scale laser operating point andpermit the feedback circuit to operate over a wide rangeof photodiode current.

The LDX-3620B is compatible with a large selection of laser diode mounts.
Shown is the LDX-3620B with an LDM-4412 TO-Can laser diode mount.

8

LASER DIODE PROTECTION
Laser diodes are extremely sensitive to electro-static
discharge, excessive current levels, current spikes
or transients from power surges or other laboratory
equipment. The LDX-3620B protects laser diodes fromthese potentially damaging events through instrument
features such as adjustable current limit and circuitdesign. Slow start circuits minimize power up transientsand a shorting relay across the output maintains thelaser leads at the same potential until the output isenabled.
Instrument current source response is tested to IEC
surge and electrically fast transients (EFT) standards.
The current source output is floating relative to chassis
ground to prevent any potentially damaging common
ground coupling between instruments or machineryand the laser diode.

A CHOICE OF LASER CONTROL MODES
The LDX-3620B can be operated at full-scale current
in constant current low bandwidth, constant current
high bandwidth or constant optical power mode. The
constant current low bandwidth mode provides stable
DC current to the laser diode while offering lowest
current noise. In constant current high bandwidthmode, an external control voltage is summed into the
output current stage allowing DC or modulated voltage
control of the output up to a 1 MHz bandwidth. For
laser protection, the modulation port is implemented

Ultra Low Noise
Laser Diode
Current Source

LDX-3620B Output Current Drift106Output Change (ppm)

LDX
3620B

4
2
0
-2
-4
-6
-8
-10
0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Elapsed Time (Hrs)

The LDX-3620B delivers <10ppm output current drift
over a one hour operating time.

EXTERNAL CURRENT CONTROLThe current output of the LDX-3620B can be controlled
by an external voltage source; either a DC signal oran alternating waveform for applications requiring DC
biasing and/or linewidth broadening, wavelength control
or amplitude modulation. One or two external voltage
wave forms can be used to modulate the output current
through the front panel modulation input ports. Bothinputs can be AC or DC coupled to the current source
drive circuits. The transconductance of each input differs
by a factor of 10 for modulated and error signal summing
to the drive circuits. In all modes of operation, thevoltage inputs are summed with the front panel current
controls for current control to the laser.

LONG LIFE BATTERIESPUT OUR EXPERTISE TO WORKThe LDX-3620B can be operated up to 16 hours on a fullcharge making it ideal for overnight testing. A second, user
installable battery operation is available which doubles the
instrument operating time under battery power.

ILX Lightwave is a recognized world leader in Laser
Diode Instrumentation and Test Systems. Our products
are not only renowned for their reliability, quality, andvalue, they’re backed by industry leading after-sales
support.

Monitoring the battery charge level any time during
instrument operation is easy with a front panel battery
charge indicator. Pushing the switch on the left of thedisplay indicates a charge level up to 100% in 25%
intervals.
The internal batteries provide the benefits of lower noise
without the drawbacks of battery powered instruments.
Lead acid batteries with good charge retention and charge
recoverability were chosen. A DC input to the instrumentwith a battery charge mode is provided for charging thebatteries even during instrument operation.
Low battery circuits were designed into the instrument tosafely shut down the instrument if the battery charge gets
below required instrument operating levels.

For more information about the LDX-3620B, call us today
or visit us at www.ilxlightwave.com.

Ultra Low Noise
Laser Diode
Current Source

LDX
3620B

ULTRA LOW NOISE AND HIGHSTABILITY
A lead acid battery and careful design and attention todetail in component selection, instrument and circuitboard design allow the LDX-3620B to achieve an orderof magnitude lower noise levels than AC powered
current sources.
With proper cabling and laser diode mounting,current noise levels of <100 nA can be achieved;
critical performance for spectroscopic, coherent
communications, and other applications requiring
narrow linewidths.
The same attention to detail also allows the LDX-3620B
to achieve current source stability on the order of 10ppm
over any one hour period in any instrument mode ofoperation.

as a differential input allowing the control voltage andthe instrument’s laser output to use different grounds.
The constant power mode maintains constant opticaloperation of the laser diode by measuring thephotocurrent from the diode’s rear-facet photodiode,or from an external photodiode in a feedback control
loop to the current source. Coarse and fine gain
adjustments on the front panel are provided to scale
the display to the full scale laser operating point andpermit the feedback circuit to operate over a wide rangeof photodiode current.

The LDX-3620B is compatible with a large selection of laser diode mounts.
Shown is the LDX-3620B with an LDM-4412 TO-Can laser diode mount.

8

LASER DIODE PROTECTION
Laser diodes are extremely sensitive to electro-static
discharge, excessive current levels, current spikes
or transients from power surges or other laboratory
equipment. The LDX-3620B protects laser diodes fromthese potentially damaging events through instrument
features such as adjustable current limit and circuitdesign. Slow start circuits minimize power up transientsand a shorting relay across the output maintains thelaser leads at the same potential until the output isenabled.
Instrument current source response is tested to IEC
surge and electrically fast transients (EFT) standards.
The current source output is floating relative to chassis
ground to prevent any potentially damaging common
ground coupling between instruments or machineryand the laser diode.

A CHOICE OF LASER CONTROL MODES
The LDX-3620B can be operated at full-scale current
in constant current low bandwidth, constant current
high bandwidth or constant optical power mode. The
constant current low bandwidth mode provides stable
DC current to the laser diode while offering lowest
current noise. In constant current high bandwidthmode, an external control voltage is summed into the
output current stage allowing DC or modulated voltage
control of the output up to a 1 MHz bandwidth. For
laser protection, the modulation port is implemented

Ultra Low Noise
Laser Diode
Current Source

LDX-3620B Output Current Drift106Output Change (ppm)

LDX
3620B

4
2
0
-2
-4
-6
-8
-10
0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Elapsed Time (Hrs)

The LDX-3620B delivers <10ppm output current drift
over a one hour operating time.

EXTERNAL CURRENT CONTROLThe current output of the LDX-3620B can be controlled
by an external voltage source; either a DC signal oran alternating waveform for applications requiring DC
biasing and/or linewidth broadening, wavelength control
or amplitude modulation. One or two external voltage
wave forms can be used to modulate the output current
through the front panel modulation input ports. Bothinputs can be AC or DC coupled to the current source
drive circuits. The transconductance of each input differs
by a factor of 10 for modulated and error signal summing
to the drive circuits. In all modes of operation, thevoltage inputs are summed with the front panel current
controls for current control to the laser.

LONG LIFE BATTERIESPUT OUR EXPERTISE TO WORKThe LDX-3620B can be operated up to 16 hours on a fullcharge making it ideal for overnight testing.

ILX Lightwave is a recognized world leader in Laser
Diode Instrumentation and Test Systems. Our products
are not only renowned for their reliability, quality, andvalue, they’re backed by industry leading after-sales
support.

Monitoring the battery charge level any time during
instrument operation is easy with a front panel battery
charge indicator. Pushing the switch on the left of thedisplay indicates a charge level up to 100% in 25%
intervals.
The internal batteries provide the benefits of lower noise
without the drawbacks of battery powered instruments.
Lead acid batteries with good charge retention and charge
recoverability were chosen. A DC input to the instrumentwith a battery charge mode is provided for charging thebatteries even during instrument operation.
Low battery circuits were designed into the instrument tosafely shut down the instrument if the battery charge gets
below required instrument operating levels.

For more information about the LDX-3620B, call us today
or visit us at www.ilxlightwave.com.

LDX
3620B
Ultra Low Noise
Laser Diode
Current Source

Specifications
GENERAL

DRIVE CURRENT OUTPUT1
Output Current Range:
0 to 200 mA
Compliance Voltage:< 5V
Temperature Coefficient:< 20 ppm / oC
2
Short Term Stability:
5 minutes:< 4 ppm
30 mintues:< 10 ppm
1 hour:< 10 ppm
2< 50 ppm
Long Term Stability (12 hours):
Noise and Ripple (rms):3
Charge Mode Operation
Low Bandwidth Mode (100 Hz): < 1.0 A
Low Bandwidth Mode (100 KHz): < 2.0 AHigh Bandwidth Mode (100 KHz): < 3.0 AHigh Bandwidth Mode (1 MHz): < 5.0 A
Battery Operation
Low Bandwidth Mode (100 Hz): < 70 nA
Low Bandwidth Mode (100 KHz): < 250 nA
High Bandwidth Mode (100 KHz): < 600 nA
High Bandwidth Mode (1 MHz): < 750 nA
Transients: 4
Operational (output on/off):< 10 A
Operational (power on/off):< 1mA

0 to 500 mA< 5V< 20 ppm / oC
< 4 ppm< 10 ppm< 10 ppm< 50 ppm< 1.0 A
< 2.0 A
< 3.0 A
< 7.0 A
< 120 nA
< 400 nA
< 900 nA
< 2.0 A
< 10 A< 1 mA

DRIVE CURRENT LIMIT SETTINGS
Range:
Accuracy (% of FS):

10 to 500 mA+5 mA

DC Input Power Requirements:
Maximum Current Draw
100VAC to 120VAC:
220VAC to 240VAC:
Batteries
Battery Operation Time:7
Battery Charge Time:+12V Supply
Type:
Capacity:
Charge Operating Temperature:
Discharge Operating Temperature:
Weight:-12V Supply
Type:
Capacity:
Weight:Size (HxWxD):
Weight:Operating Temperature:
Storage Temperature:
Humidity:
Regulatory Compliance:

PHOTODIODE FEEDBACKType:PD Current Input Range:

Differential
20 to 2000.0 µA

Differential
20 to 2000.0 µA

EXTERNAL ANALOG MODULATION
Input 1:
Transfer Function:
Bandwidth (3dB; DC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Bandwidth (3dB; AC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Input Impedance:
Input 2:
Transfer Function:
Bandwidth (3dB; DC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Bandwidth (3dB; AC coupled)6High Bandwidth Mode:
Low Bandwidth Mode:
Input Impedance:

10V
2 mA/V

10V
5 mA/VDC to 1 MHz
10 kHzDC to 1 MHz
10 kHz100 Hz to 1 MHz
100 Hz to 10 kHz
1 K
10V
20 mA/V

100 Hz to 1 MHz
100 Hz to 10 kHz
1 K
10V
50 mA/V

DC to 1 MHz
10 kHzDC to 1 MHz
10 kHz100 Hz to 1 MHz
100 Hz to 10 kHz
1 K

100 Hz to 1 MHz
100 Hz to 10 kHz
1 K

0 to 199.99 mA
0.01 mA
0.1% FS
0 to 1999.9 µA
0.1 µA+4 µA

0 to 500.0 mA
0.1 mA
0.2% FS
0 to 1999.9 µA
0.1 µA+4 µA

MEASUREMENT
Output Current Range:
Output Current Resolution:
Output Current Accuracy:
Photodiode Current Range:
Photodiode Current Resolution:
Photodiode Current Accuracy:

INPUT/OUTPUT CONNECTORS
Photodiode:
Modulation (Input 1):
Modulation (Input 2):
Laser Current Source:
DC Power Supply:

100VAC - 120VAC +10%, 47 to 63 Hz
220VAC - 230VAC +10%, 47 to 63 Hz

Product Features

1.6A
1.6A
16 hours
15 hours

Battery operated dual range
200mA/500 mA current source

Lead acid12 amp-hour
0 - 40oC-20oC - 50oC
3.94 kg (8.68 lbs)

<100 nA rms noise in battery mode

Lead acid
2.2 amp-hour
0.94 kg (2.07 lbs)
5” x 13.4” x 16.3”
127mm x 340mm x 414mm
25.4 lbs.; 11.11 kg
0oC to 40oC
-40oC to 60oC
Up to 80%, non-condensing
CE Certified; EMC Directive 2004/108/
EC per standard EN61326-1:2006;
Low Voltage Directive 2006/96/EC per
standard EN61010-1:2001

Better than 10ppm stability over
one hourConstant current and constant power
operating modes
Laser diode protection and error
detection circuits protect lasers in all
operating modes

NOTES

1. Unless otherwise noted, all specifications measured at 23°C ±3°C after one-hour warm-up
period.
2. Over the specified period, half-scale output into a temperature controlled resistive load.
3. Measured electrically, with a 24 load evaluating AC coupled rms value over the specified
bandwidth.
4. Maximum output current transient resulting from normal operational situations (e.g., power
on-off, current on-off), as well as accidental situations (e.g., power line plug removal).
5. Internal specification only, not to be published.
6. Sine wave with 5V peak to peak modulation at half scale output
7. Battery operating time is the same for both 200 mA and 500 mA ranges, instrument circuitry
draws 500 mA in either current range.
8. Measurement accuracy specification becomes non-linear after 180mA in 200mA range andat 1800uA for photodiode current measurement. Total non-linearity error not to exceed +0.2%
of current measurement full scale or +4uA of photodiode measurement current.

ORDERING INFORMATION
LDX-3620B
CC-305S
CC-306S
LDM-4412
LDM-4405
LDM-4407
LDM-4982
LDM-4984

Ultra Low Noise Current Source
Current Source/LD Mount Interconnect Cable
Current Source Unterminated Interconnect Cable
Temperature Controlled TO-can Laser Diode Mountwith Collimating Lens
Low Cost TO-Can Laser Diode Mount
Temperature Controlled TO-can Laser Diode Mount
DIL Laser Diode Mount
Butterfly Laser Diode Mount

Two modulation inputs with up to 1MHz
bandwidth for precise laser tuning
Battery charge mode with front panel
charge level indication

The LDX-3620B is a battery powered, ultra low noise current
source, optimized for narrow linewidth or stable wavelength
laser diode applications. The all new instrument provides aprecision current output with <100 nA rms noise and <10ppm
stability. The current source can be operated in one of two output
ranges in constant current or constant power operating modes.
Additionally, two AC or DC coupled modulation inputs, fine andcoarse, can control the current source for precise laser diodewavelength or linewidth tuning with a bandwidth up to a 1 MHz.
All of ILX Lightwave’s proven laser diode protection features
are designed into each model, which include adjustable current
limits, a floating output, shoring relays, slow turn-on circuits, andtransient protection during power up and laser operation. Error
indicators help resolve set up problems quickly such as open
circuit and power limits.
Additional features include long battery life between charges,
a battery charge mode and front panel charge indicator making
the LDX-3620B a reliable test instrument for low noise, precisionlaser wavelength control applications. The LDX-3620B is
compatible with a large selection of ILX Lightwave laser
diode TO-can, butterfly, and DIL laser mounting fixtures withinterconnect cables for fast, easy system set up.

Other laser diode mounts are available; contact sales@ilxlightwave.com
for more information.
In keeping with our commitment to continuing improvement, ILX Lightwave reserves the right to change
specifications without notice or liability for such changes.

9-pin d-sub rear panel; BNC, rear panel
BNC, front panel
BNC, front panel
9-pin d-sub rear panelStandard Type R1B: DIN 5-pin

Battery Powered Ultra Low Noise
Laser Diode Current Source
For information call
P.O. Box 6310, Bozeman, MT 59771 • FAX: 406-586-9405

www.ilxlightwave.com

1-800-459-9459
International Inquiries: 406-556-2481
email: sales@ilxlightwave.com

Rev02.102010

LDX
3620B
Ultra Low Noise
Laser Diode
Current Source