LIV 110 Laser Diode Characterization System Artifex Engineering e.K. Dortmunder Str. 16-18 26723 Emden, Germany General Manager: Dr. Steven Wright Registry number: HRA 200036 Tel: +49-(0)4921-58908-0 eMail: [email protected] Web: http://www.afx-eng.com/

3.3 Optical Power Measurement

1. General Information The LIV110 is a powerful test instrument for use in the lab and in production environments. This instrument is ideal for laser diode characterization, quality control of incoming goods and for OEM applications. This compact unit comprises the current source as well as the data acquisition and communication hardware. The LIV110 supplies a laser diode with well defined currents in the form of a staircase. During the current sweep, the instrument measures the optical power of the laser diode (L), the drive current (I) and the voltage drop across the laser diode (V). In addition,...

INPUT Maximum OD1, OD2 measureable power and OD3 refer to use with the respective attenuating filter Minimum measureable power Monitor Current OUTPUT Laser Diode Current Gain 0 Gain 1 Gain 2 Current Resolution Compliance Accuracy Offset Risetime / Falltime Number of Measurements per Channel Number of Measurement Channels GENERAL Power Supply Communication Dimensions

3. Connections 3.1 Power Supply The power supply is 6V via a barrel socket. Please use only the power supply supplied with the unit. 3.2 Communication The communication with the LIV110 is via USB 2.0 with a baud rate of 115200 kB/s. A Hardware – Handshake using RTS/CTS is employed to ensure secure communication. 3.3 Optical Power Measurement The connector denoted „Detector“ is compatible with the calibrated detector heads of the OPM150 series from Artifex Engineering. The calibration data are read out of the memory chip in the detector plug in order to calculate the optical power input. Please...

4. Measurement Cycle Before beginning the first measurement, the calibration factor for the wavelength of the laser to be measured should be called up (see “Miscellaneous”, page 10). A measurement begins by uploading the measurement parameters. These parameters are stored in the instrument but they are volatile – that is, the parameters are not stored after powering down the LIV110. Command: U The definition and syntax of the bytes is defined in section 5.2 on page 8. The measurement process is initiated by the command $G. The end of the measurement is signalized when the LIV110 sends either...

4.1 CW Mode The CW mode uses the current driver of the LIV110 without making any measurements. The upload parameters set the duration and current value. The duration is set in steps of 1ms from 1 to 60,000 – that is, durations of 1ms to 60s. The current which is generated is set via the parameter “upper current limit”. The maximum current in this mode has been internally limited to 50mA in order to not overheat the end stage. The instrument sends a “%” character when the “on” cycle has finished. No further data (eg data header) are communicated. The current can be interrupted by sending byte...

5.2 Command List Receipt of all commands will be recognized by an echo from the microcontroller. This echo should be read and checked. The flow control ensures error free communication. If a command or upload is not recognized properly by the microcontroller, a time-out after 1.5 s will reset the internal parameter. The upload parameter storage is non-volatile – the values remain valid following a restart of the unit. For safety reasons, the driver starts in a current off state. The following commands are available: Upload Parameter upload: Command: U Echo: <13> (= Carriage Return) The numbers...

Measurement Start measurement: Command: $G Response if the measurement is erroneous: „!“ followed by the error code: E1 : no detector connected E5 : power on the monitor diode is too low Response following a successful measurement: „%“ (indicating end of measurement). followed by header data: 1): gain factor for the optical channel 2): gain factor for the laser diode monitor input channel 3): low byte of the number of data sets 4): high byte of the number of data sets 5): number of channels and subsequently followed by the measurement data (the number of measurement cycles is given in the header...

Miscellaneous Information about the instrument: Command: $I This command calls up information about the instrument and the detector attached to the „Detector” input. Each line is terminated with Byte 13 (= Carriage Return). Line 1: Model (LIV110) Line 2: Serial number Line 3: Date of manufacture Line 4: Serial number of the detector Line 5: Lower calibration wavelength of the detector Line 6: Upper calibration wavelength of the detector If no detector is connected, line 4 will contain the error code “E4” and the data tranfer is terminated with the carriage return. Calibration factor: Command:...