Lightwave Communications LDX-3232 manual Modulating the Laser Current Source

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C H A P T E R 5

FUNCTIONS AND FEATURES

Using the LDX-3232 Current Sources’s BNC Interlock Connection

Using the LDX-3232 Current Sources’s BNC Interlock Connection

The LDX-3232 BNC interlock connection is designed to allow an external emergency input signal to turn the current output off. The BNC interlock is TTL compatible and configured to be normally closed (as opposed to the DB-9 interlock connection, that is normally open). The BNC interlock connection, when left unconnected, is pulled to a logic high with a 100 kΩ resistor. High values

(+5 V) will keep the interlock closed (current source in the operational state), while low values (0 V) will open the BNC interlock (forces the output off). Once the BNC interlock is opened, the output will stay off until the interlock is closed again, and you re-enable the output.

BNC Interlock Usage Example

When using the LDX-3232 Current Source to drive a temperature controlled laser diode, the BNC interlock can be used to accept an error signal from the laser diode temperature controller unit. Linking the LDX-3232 Current Source to a temperature controller* with the ability to signal when its temperature control has gone outside of some tolerance window will allow the LDX-3232 to safely shutoff its output before thermal damage occurs to the laser diode.

*The ILX Lightwave LDT-5900 series of temperature controllers include an output BNC connector that is compatible with the BNC interlock feature of the LDX-3232. The output BNC connector of the LDT-5900 has a TTL compatible output signal that will signal when the temperature control has gone outside of a programmable temperature window. For more information about the LDT-5900 series of temperature controllers, please call 1-800-459-9459 (USA or Canada only), 1-406-556-2481 (International), or go to www.ilxlightwave.com.

Modulating the Laser Current Source

The LDX-3232 Current Source allows a modulated signal to be superimposed on the source output current. For example, assume you are using an LED for your experiment where you need to operate the LED in constant current at POP =

100 mW, with a modulated signal from 3 to 30 kHz. The experiment requires the LDX-3232's laser Current Source to be configured for the 2000 mA range, high bandwidth mode with a limit of 1750 mA. The allowable bandwidth of the modulated analog signal, defined as the 3 dB roll off point, is dependent on the output current range and the mode (constant current low/high bandwidth). See the section, LASER CURRENT SOURCE SPECIFICATIONS, in Chapter 1 for external analog modulation bandwidth specifications.

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Contents User’s Guide Page Table of Contents Remote Operation Command Reference Iv LDX-3232 List of Figures Vi LDX-3232 List of Tables Viii LDX-3232 Safety Information and the Manual General Safety ConsiderationsSafety Symbols Safety Marking SymbolsWarranty Claims for Shipping Damage Comments, Suggestions, and Problems Description of the problemModel Number Serial Number End-User Name Company Phone Fax Xiv LDX-3232 Introduction and Specifications Product OverviewInitial Inspection Installing Your LDX-3232 High Compliance Current SourceAC Line Power Requirements Grounding RequirementsGpib Address Gpib ConnectorTilt-Foot Adjustment Operating the LDX-3232 Precision Current SourceLDX-3232 Front View Maintenance Specifications Type Pulse Width Delay TTL13 µs 12 ms Available Options and Accessories Description Model NumberApplying Power to Your LDX-3232 Power On SequenceConnecting to the Laser Power On StateCommon Laser Cathode Photodiode Anode Back Panel LD Connector Interlock ConnectionsSetting the PD Bias Photodiode ConnectionsGrounding Considerations Operating a Laser in Constant Current I Mode Front Panel OperationDisplay Setting Up the Precision Current Source E R a T I O N Operating a Laser in Constant Power P Mode Entering Photodiode Responsivity ValuesMethod to calculate the responsivity is suggested below Error Indicators LDX-3232 Error IndicatorsError Indicators LDX-3232 Reading the Gpib Address Changing the Gpib AddressLDX-3232 Current Source Command Set Command SyntaxChanging Operation from Local to Remote OFF OLD NEW True False SET Reset LASLDI? Command Paths LDX-3232 Command Path StructureIEEE488.2 Command Commands LDX-3232 Frequently Used Commands NoneLIM Status Reporting Event and Condition RegistersOperation Complete Definition LDX-3232 Status Reporting Schematic Diagram Disabled 10 N/A Enabled 11 N/A 12 N/A 13 N/A 14 N/A 15 N/A Output Off RegisterLASerENABleOUTOFF nrf LASerENABleOUTOFF? Command Timing and Completion Error MessagesError Code Classifications Response MessageMode Used to enter the laser current calibration mode Used to create a delay in the execution of furtherCommands Used to enter the laser voltage calibration modeSets the enable register for Laser conditions Returns status of photodiode monitor power displayEnables Laser display to show parameter values Returns the value of the LAS conditions enable registerUsed to enable/disable the front panel modulation input Used to return the optical power from monitorUsed to set the constant optical power setpoint, if Or P optical powerReturns the elapsed time since the timer was last reset Returns the status of the Term commandPowered up Used to return the Laser setpoint tolerance valueLDX-3232 Device-Dependent Commands Command Description FormatLDX-3232 Device-Dependent Command Reference DelayERRors? LASerCALMDCalmd LAS Calpd Responsivity CAL PD parameter setting Syntax Diagram LASerCALMD?Selected. This procedure is outlined in Chapter LASerCALLDICalibration for that bandwidth LDI LAS CAL LASerCALLDI?LASerCALLDV LAS CAL LDVTrue measured value. This procedure is outlined in Chapter LASerCALLDV?LASerCALMDI MDI LASerCALMDI?LASerCOND? LAS CAL IPDLASerDEC LAS DIS LASerDISplayLASerDISplay? LASDIS?Lasdisldi LASerDISplayLDILASerDISplayLDI? LDILASerDISplayLDV? Voltage measurement Syntax DiagramLASerDISplayLDV LASDISLDV?LAS DIS MDI LASerDISplayMDILASerDISplayMDI? LAS DIS IPDPPD LASerDISplayMDPLASerDISplayMDP? LAS DIS MDPLAS DIS Param LASerDISplayPARAMLASerDISplaySET LAS DIS SETLASerENABleCOND LASerDISplaySET?LASDISPLAYSET? LASerENABleCOND? BitLAS Enab Cond Action enables the Laser status event register so that LASerENABleEVEntAn nrf value whose sum represents the bits that are enabled LasenabeventLASerENABleEVEnt? LAS Enab EVELASerENABleOUTOFF LASerENABleOUTOFF? LAS Enab OutoffLASerEVEnt? LASerENABleEVEnt commandCommand while the condition status is constantly changing LAS EVELASerINC Function for the Laser outputLASerLDI? This measurement is updated approximately once every 600 msLASerLDI LAS LDIFor LDV calibration LASerLDVLASerLDV? LAS LDVLimit in use depends on the Laser output range selection LASerLIMitI2LASerLIMitI2? LAS LIMLASerLIMitI4? Displayed, and then releasing the SET switchLASerLIMitI4 LASLIMI4?LASerLIMitMDP LASerLIMitMDP?MDP LAS LIM LASerLIMitV LASerLIMitV?MDI LAS IPD LASerMDILASerMDI? MDP P PD setpoint would be usedLASerMDLN LASerMDLN?LAS Mdln LASerMDP LASerMDP?MDP LAS LASerMODE? LAS ModeLAS Mode Ihbw LASerMODEIHBWLASerMODEMDP LAS Mode MDPLASerMODEILBW LasmodeilbwLASerOUTput LASerOUTput?LAS OUT LAS RAN LASerRANgeLASerRANge? LASRAN?LASerSETLDI? Where the response is the constant I setpoint value, in mA30 µA, for use in constant P mode with Calpd = LASerSETMDI?LASerSTEP Where the response is the constand PPD setpoint, in mWLASerSETMDP? 100 µALASerTOLerance LASerTOLerance commandLASerSTEP? LAS TOLSecond is the time window, in seconds LASerTOLerance?MESsage MESMESsage? RADixRAD Term 0 command is sent or the LDX-3232 is powered offRADix? Means hexadecimal, and OCT means octalLDX-3232 was last powered up Time clock is independent of the Timer clockTime Last TIMER? query is returned Since the last TIMER? query was issuedTimer Seconds since the last TIMER? query was issuedFunctions and Features Saving and Recalling from the Front PanelUsing the Laser Compliance Voltage Adjustment Saving and Recalling Under Remote OperationUsing the LDX-3232 Current Source’s Trigger Function LDX-3232 Rear PanelModulating the Laser Current Source BNC Interlock Usage ExampleModulating the Laser Current Source Functions and Features Calibration and Troubleshooting Calibration OverviewDescription Manufacturer/Model Specification Recommended EquipmentDMM Range Local Calibration of the LDX-3232 Current SourceCurrent Source Calibration Current LimitIPD Current Calibration Set equal to zero Constant powerCAL PD IPD Setpoint2000 mA Laser ModeLaser Forward Voltage Measurement Calibration Set to FS full scale of rangeGpib Command Remote Calibration of the LDX-3232 Current SourceLimit Lasldi nrf value command IPD Setpoint Function State Gpib Command EEPROM, Lllll will be displayed on the display the laser Troubleshooting GuideGeneral Current source must be recalibratedFeature can be defeated via the Lasenableoutoff Command101 Response Message
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