Low noise butterfly laser diode controller
Koheron CTL101 is a low noise current driver with modulation combined with a temperature controller. It is designed to drive narrow-linewidth laser diodes in butterfly package. The CTL101 fits in a 75 mm x 75 mm square, uses a single 5 V supply, and can operate between 0 and 50°C. The CTL101 is conduction-cooled. It comes with an aluminum base plate and a zero insertion force socket for easy mounting.
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Specifications
CTL101 laser controller is available for type 1 lasers (CTL101-1-) and type 2 lasers (CTL101-2-).
| B-100 | B-200 | B-400 | B-800 | |
|---|---|---|---|---|
| Current driver | ||||
| Laser current | 0 mA to 110 mA | 0 mA to 220 mA | 0 mA to 440 mA | 0 mA to 880 mA |
| Compliance voltage(5 V power supply) | 2.2 V | 2.2 V | 2.2 V | 2.2 V |
| Compliance voltage(6 V power supply) | 3.2 V | 3.2 V | 3.2 V | 3.2 V |
| RMS noise(10 Hz to 1 MHz, L and M modulation gains) | 120 nArms | 200 nArms | 390 nArms | 810 nArms |
| RMS noise(10 Hz to 1 MHz, H modulation gain) | 150 nArms | 280 nArms | 560 nArms | 1160 nArms |
| Current noise density(1 kHz, M modulation gain) | 110 pA/√Hz | 220 pA/√Hz | 420 pA/√Hz | 820 pA/√Hz |
| Current limit(L setting) | 60 mA | 150 mA | 300 mA | 600 mA |
| Current limit(H setting) | 125 mA | 250 mA | 500 mA | 1000 mA |
| Temperature coefficient | 15 ppm/°C | 15 ppm/°C | 15 ppm/°C | 15 ppm/°C |
| Slow start(90 % setpoint) | 250 ms | 250 ms | 250 ms | 250 ms |
| AC modulation cutoff frequency | 1.5 MHz | 1.5 MHz | 1.5 MHz | 1.5 MHz |
| DC modulation | ||||
| Modulation gain(L setting) | 0.5 mA/V | 1 mA/V | 2 mA/V | 4 mA/V |
| Modulation gain(M setting) | 5 mA/V | 10 mA/V | 20 mA/V | 40 mA/V |
| Modulation gain(H setting) | 50 mA/V | 100 mA/V | 200 mA/V | 400 mA/V |
| 3 dB modulation bandwidth | 10 MHz | 10 MHz | 10 MHz | 10 MHz |
| Modulation input impedance | 50 Ω | 50 Ω | 50 Ω | 50 Ω |
| Modulation input range | ±1 V | ±1 V | ±1 V | ±1 V |
| TEC controller | ||||
| Maximum current | 0.8 A | 1.2 A | 1.2 A | 1.2 A |
| Temperature range(10 K thermistor) | 10 °C to 35 °C | 10 °C to 35 °C | 10 °C to 35 °C | 10 °C to 35 °C |
| Compliance voltage | -3 V to 3 V | -3 V to 3 V | -3 V to 3 V | -3 V to 3 V |
| Temperature stability | 0.0015 °C/°C | 0.0015 °C/°C | 0.0015 °C/°C | 0.0015 °C/°C |
| Laser power monitor | ||||
| Photodiode current | 0 mA to 1 mA | 0 mA to 1 mA | 0 mA to 1 mA | 0 mA to 1 mA |
| Gain | 3.9 V/mA | 3.9 V/mA | 3.9 V/mA | 3.9 V/mA |
| Bandwidth | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Other | ||||
| Outside dimensions | 75 mm x 85 mm x 27 mm | 75 mm x 85 mm x 27 mm | 75 mm x 85 mm x 27 mm | 75 mm x 85 mm x 27 mm |
| Weight | 103 g | 103 g | 103 g | 103 g |
| Supply voltage | 4.9 V to 6.5 V | 4.9 V to 6.5 V | 4.9 V to 6.5 V | 4.9 V to 6.5 V |
| Operating temperature | 0 °C to 60 °C | 0 °C to 60 °C | 0 °C to 60 °C | 0 °C to 50 °C |
| Compatible lasers | Floating diodes | Floating diodes | Floating diodes | Floating diodes |
More Laser drivers
Current driver
The figure below shows the relative current change of the CTL101 laser controller set at 800 mA current (CTL101-2-B-800) during its first 100 hours of operation:
The current stability of the controller after 100 hours is shown below:
After a subsequent power-on, the CTL101 controller takes only one minute to settle the laser current within 10 ppm of the setpoint value:
Current modulation
The CTL101 controller has two current modulation inputs available on SMA connectors. The DC modulation input allows to modulate the current setpoint between DC and 10 MHz. A jumper allows to choose between 3 modulation gains (2 mA/V, 20 mA/V and 200 mA/V for the 400 mA version).
The AC modulation input can be used to modulate the laser above 1 MHz with a modulation gain of 20 mA/V:
Current noise
The figure below shows the current noise of the CTL101 controller operating at rated current with the modulation gain set to M:
Temperature stability
The figure below shows the variation of the output current against the ambient temperature for controllers operating at rated current:
Temperature controller
The temperature controller consists of a precision Wheatstone bridge, an analog PID controller and a linear current driving stage. PID gains are fixed and have been adjusted for a typical butterfly laser diode. Temperature setpoint is adjusted with a precision trimming potentiometer.
