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 a precision 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 and coarse, can control the current source for precise laser diode wavelength 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 fl oating output, shoring relays, slow turn-on circuits, and
transient 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, precision laser 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 with interconnect cables for fast, easy system set up.
Ultra Low Noise and High Stability
A lead acid battery and careful design and attention to detail in component selection, instrument and circuit board design allow the LDX-3620B to achieve an order of 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 of operation.
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 from these potentially damaging events through instrument features such as adjustable current limit and circuit design. Slow start circuits minimize power up transients and a shorting relay across the output maintains the laser leads at the same potential until the output is enabled.
Instrument current source response is tested to IEC surge and electrically fast transients (EFT) standards. The current source output is fl oating relative to chassis ground to prevent any potentially damaging common ground coupling between instruments or machinery and the laser diode.
A Choice of Laser Diode 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 bandwidth mode, 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 as a differential input allowing the control voltage and the instrument’s laser output to use different grounds.
The constant power mode maintains constant optical operation of the laser diode by measuring the photocurrent 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 and permit the feedback circuit to operate over a wide range of photodiode current.
External Current Control
The current output of the LDX-3620B can be controlled by an external voltage source; either a DC signal or an 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. Both
inputs 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, the voltage inputs are summed with the front panel current controls for current control to the laser.
Long Life Batteries
The LDX-3620B can be operated up to 16 hours on a full charge making it ideal for overnight testing.
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 the display indicates a charge level up to 100% in 25% intervals.
The internal batteries provide the benefi ts 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 instrument with a battery charge mode is provided for charging the batteries even during instrument operation.
Low battery circuits were designed into the instrument to safely shut down the instrument if the battery charge gets below required instrument operating levels.
Put Our Expertise to Work
ILX Lightwave is a recognized world leader in laser diode instrumentation and test systems. Our products are not only renowned for their reliability, quality, and value, they’re backed up by industry leading after sales support.
Laser Diode Driver Specifications
Full specifications can be found in the LDX-3620B Brochure .
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|
LDX-3620B
|
| Driver Output Current |
| Output Current Range (mA) |
0-200 mA |
0-500 mA |
| Laser Output Compliance Voltage (V) |
0-5.0 V |
0-5.0 V |
| Temperature Coefficient (ppm/°C) |
<20 ppm |
<20 ppm |
| Current Output Short-Term Stability (1 h) (ppm FS) |
<10 ppm |
<10 ppm |
| Current Output Long-Term Stability (24 h) (ppm FS) |
<50 ppm |
<50 ppm |
| Noise and Ripple (rms) |
| Laser Output Noise/Ripple (rms) Hi BW(100 kHz) |
<600 nA |
<120 nA |
| Laser Output Noise/Ripple (rms) Lo BW(100 kHz) |
<70 nA |
<900 nA |
| Transients |
| Output On/Off (µA) |
<10 |
| Power On/Off (mA) |
<1 |
| Photodiode Feedback |
| Type |
Differential |
| Monitor Current Range (µA) |
20-2000 µA |
| External Analog Modulation |
| Input Range (1k Ohm) |
0-10 V |
| Transfer Function (mA/V) |
20 mA/V |
50 mA/V |
| Bandwidth (3dB) |
| External Modulation Bandwidth Hi BW |
DC to 1 MHz |
| External Modulation Bandwidth Lo BW CW Mode (kHz) |
DC to 10 |
For additional questions contact ILX Lightwave directly at 800-459-9459 or sales@ilxlightwave.com.
LDX-3620B Models
Accessories
Suggested Mounts
