Precise control of diode lasers and the acquisition of measured values
The DL100 / 110 series offers modules for the precise control of diode lasers and for acquisition of measurement data.
The different modules of the series are plugged-in into the DC100 / 110 rack, which is available in several versions with different widths and heights.
For standard applications normally the modules DC (power supply and monitoring module), DCC (diode current control) and DTC (temperature control) are sufficient.
This modular system has been developed for TOPTICA Photonics AG and can be bought there.In particular, the diode laser DL100 that is controlled by the DL100/110 system ca be bought at TOPTICA Photonics AG.
The DCB module is an interface module providing direct access to the internal analog control signals of the DC100/110 rack.
Most of the rack-internal parameters can be read out as set values and as actual values
Allows an external control of the DL system via a PC with DA-/AD-interface card
Specifications
Allows data transfer to and from a PC by means of a standard Sub-D25 cable
Parameters can be read out as well as the system can be controlled by a computer
Mostly all internal parameters can be read out as set values (Xset) and as actual values (Xact)
All control wires are decoupled via resistors or buffers in order to avoid disturbances in the system
Four control channels can be controlled from extern (configurable via jumpers)
One selectable parameter can be supervised or fed in via a BNC-connector
Technical data
Standard input impedance for reading out of parameters: 10 kΩ
Input sensitivities for the electrical parameters:
Current of the DCC100/500 mA: 0 V = 0 mA 1 V = 10 mA
Current of the DCC100/ 3 A: 0 V = 0 mA 1 V = 100 mA
Temperature: 0 V = 0 °C 1 V = 10 °C 1 V = 10 °C
Diode Temperature Control Module – DTC
The DTC module is a highly stable temperature control unit for laser diodes, like used in spectroscopic applications for example.
Available in three versions:
a) For driving of a cooler / heater by means of a thermo-electric element (Peltier element)
b) As SVL version (set-point velocity limitation) with highly-precise defined velocity limitation, like mostly required for frequency doubling crystals (predefined maximum temperature change per time)
c) For the temperature control of a small mass e.g. a DFB-laser diode
Maximum output power 30 W
Specifications
Different temperature sensors are supported (thermistor 10 kΩ/neg, AD 590, etc.)
Temperature (Tset) adjustable via range switch (coarse) and 10-turn potentiometer (fine)
Minimum and maximum temperatures (Tmin, Tmax) adjustable via precision trimming potentiometers
Control of the thermo-electric element via SubD9-Verbinder
Maximum current for the thermo-electric element (ITECmax) adjustable via precision trimming potentiometer
Polarity switch for adaptation to different thermo-electric elements
SVL version (set-point velocity limitation) with very precisely defined velocity limitatio
Technical Data
Maximum output current for the thermo-electric element (ITECmax): 0 to 5 A
Maximum output power: 30 W
Maximum temperature (Tmax): 0 to + 50 °C (special version – 50 to + 150 °C)
Minimum temperature (Tmin): 0 to + 50 °C (special version – 50 to + 150 °C), with Tmin < Tmax
Extremely low drift (with DL100 laser head < 2 mK)
Lock-In Regulator Module – LIR
The LIR module allows the active locking of the laser frequency of a diode laser to a desired wavelength.
This module contains mainly three functions:
Internal modulation source
Lock-in amplifier
PID-regulator
Typically, these functions are used to stabilize the laser towards an atomic absorption line or a cavity-resonance (top-of-fringe-stabilization).
Spezifikationen
Modulation signal selection between internal modulation source and external signal possible
Signal form of the internal modulation source selectable between sine and triangular
Frequency of the internal modulation source adjustable via switch (coarse) and potentiometer (fine)
Amplitude of the internal modulation source adjustable
Phase of the modulation signal adjustable via switch (coarse) and potentiometer (fine)
Decoupling and amplification of the lock-in input signal adjustable
(DC-decoupling or two different low pass filters)
Lock-in amplifier (phase detector) with integrated, adjustable low pass filter
Offset of the lock-in signal adjustable
Switchable PID-regulator with relock mechanism and adjustable P-, I- and D-terms
Output voltage of the PID regulator adjustable•Internal and external offset can be added to the output signal of the module per switch
Internal offset for the output signal is adjustable
External supervision possible by selection of the internal signals as monitor signal
Technical Data
Modulation frequency: 0.6 Hz to 14 kHz
Modulation amplitude: 0 V to 10 VSS
Cut-off frequencies of the high pass filters for decoupling of the lock-in input signal: 16 Hz, 160 Hz
Cut-off frequency of the low pass filter in the lock-in amplifier: 16 mHz to 16 kHz
Amplification of the external lock-in input signals: 1 to 3000
Lock-in bandwidth: 16 mHz up to 16 kHz
Amplitude range of relock mechanism: – 5 V to + 5 V
The PID module is a universal proportional-integral-differential regulator.
Adjustable P-, I- and D-terms
High-voltage output with 0 to 150 V (optionally as well with low-voltage output ± 10 V)
Application areas are e.g. the stabilization of a diode laser towards a flank of an atomic resonance or an Airy peak of a Fabry-Perot-interferometer, the stabilization of a laser resonator by driving a piezo actuator, or the compensation of disturbances like acoustic noise, vibrations and temperature changes.
Specifications
Reset voltage (set point) and search speed of the PID-regulator adjustable
P-, I- and D-term each adjustable via potentiometers•Switchable relock function•Indication of the lock status via LEDs (search, unlock, relock)
External modulation or internal modulation possible (via SC module)
Output voltage adjustable via precision potentiometer•Inverted output voltage per switch selectable
External supervision possible by selection of an internal signal as monitor signal
Optionally as well with low-voltage output (± 10 V, 20 mA)
Technical Data
Output voltage: 0 V to 150 V, maximum 30 mA and maximum 8 W
Optionally with low-voltage output: – 10 V to + 10 V, maximum 20 mA
Monitor signal: – 10 Volts to + 10 Volts
Pound-Drever-Hall Detector Module PDD
The PDD module contains all functions for laser stabilization with the HF side band modulation technique (Pound-Drever stabilization).
Output voltage with defined frequency for HF modulation (typically 20 MHz)
bandwidth also suitable for resonators with high finesse
Available with one or two phase detector and error signal channels
Specification
Detection of the phase delay (dispersion) by phase comparison of a base band with a side band and generation of a Pound-Drever-signal
Internal oscillator with a defined oscillation frequency as generator for the base band signal
Output voltage of the internal oscillator externally available
Output voltage of the internal oscillator adjustable via potentiometer
Amplification of the photo diode input signal adjustable via potentiometer
Additional relative phase adjustable via potentiometer
Pound-Drever error signal externally available
Optionally as well with two phase detector and error signal channels
Technical Data
Output frequency of the internal oscillator: 20 MHz (standard, other frequencies from 5 to 40 MHz on request)
Output amplitude of the internal oscillator: adjustable to up to – 4 dBm
Output impedance of the internal oscillator: 50 Ω (standard, adaptation possible via internal resistor)
Amplitude of the second harmonic: typically < – 30 dBc at an output amplitude of – 4 dBm
Maximum input amplitude of the photo detector signal: – 7 dBm
Maximum output voltage of the error signal: – 0.8 V to + 0.8 V
Output voltage of the error signal with a regulator bandwidth of up to 1 MHz
Scan Controller Module – SC
The SC module serves for scanning the laser frequency of an external-cavity diode laser head DL100.
The DL100 is tuned by moving a grating via a piezo element.
High-voltage output
Triggering by external signal possible
Thus, a fine tuning of the wavelength of an external-cavity diode laser within the single-mode scan range is possible.
Specification
Signal form symmetry of the output signal can be adjusted (triangular or sawtooth shape)
Wavelength fine tuning of a diode laser within the single-mode scan range
Scan frequency adjustable via range switch (coarse) and potentiometer (fine)
Output amplitude adjustable via logarithmic potentiometer
Offset can be added and adjusted via a 10-turn potentiometer
Output for monitoring the internal trigger signal
Input for external trigger signal
Delay of the trigger signal adjustable via potentiometer
Internal feed forward signal for the laser diode current adjustable via trimming potentiometer (scan ratio between the output voltage of the SC, i.e. the piezo voltage, and the laser diode current)
