FALC 110 & mFALC 110
Fast laser locking module
• For linewidth reduction and phase locking (mFALC)
• PID regulator with less than 15 ns signal delay
• 90° phase delay at 45 MHz
• Addresses laser current (fast) and slow element (drift)
• Sub-Hz laser linewidths demonstrated
The Fast Analog Linewidth Control (FALC 110) is a module for advanced laser frequency stabilization tasks, such as linewidth reduction and high-bandwidth frequency locking. Due to an optimized circuit layout, the -3 dB bandwidth of the fastest signal path reaches 100 MHz.
The Mixing FALC (mFALC) additionally comprises an analog mixer for phase detection, and is designed for fast phase locking of two lasers to an external RF reference.
Applications
• High-bandwidth laser frequency stabilization • Linewidth reduction of ECDL and selected DFB lasers
• Phase locking of two lasers • Difference frequency stabilization
• Precision frequency control (BEC, quantum optics, metrology)
TOPTICA offers a wide portfolio of modules for laser linewidth manipulation: High-bandwidth regulators like FALC 110 and DigiLock 110 have been shown to achieve sub-Hertz linewidth values, whilst the LCC broadens the spectral profile to Gigahertz levels. The range of laser coherence control thus spans more than nine orders of magnitude (coherence length 130000 km .. 4 cm).
Specification
Concept Module of DC 110 series, for high-bandwidth frequency locking (FALC) or phase locking of two lasers to an external reference (mFALC) Input section
Inputs
Two high-speed differential inputs, adjustable input offset
Fast circuit branch
PID regulator
< 15 ns signal delay
Phase delay
< 45° @ 10 MHz
∼ 90° @ 45 MHzDC gain
15 dB to 80 dB
Output voltage range
Max. +/- 2 V @ 50 Ω
Slow integrator
Bandwidth
10 kHz (for grating piezo or laser temperature control)
DC gain
Typ. 110 dB
Output voltage range
Max. +/- 5 V, high-impedance load
RF input (beat signal of two lasers, mFALC only)
Frequency range
10 MHz .. 200 MHz
Max. input voltage, DC
5 V
Max. input voltage, AC
4.5 V pp
LO input (local oscillator, to be mixed with RF input, mFALC only)
Frequency range
10 MHz .. 200 MHz, sine wave preferred
Max. input voltage, DC
2 V
Max. input voltage, AC
2.8 V pp
For use with TOPTICA’s tunable diode lasers, an AC modulation input is required on the laser head (DL-MOD PCB).