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.

Request a Quotation Application Note Phase and Frequency Locking of Diode Lasers

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 MHz
DC 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
Optimum input voltage range	10 mVpp .. 700 mVpp (-35 .. +1 dBm)
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.

Additional Information

Beat measurement of two ECDLs, locked to two high-finesse cavities. One of the locks was realized with a FALC 110. The beat width was less than 0.5 Hz over 8 s. The inset shows the phase stability of the beat note (J. Alnis, MPQ Garching).

Oscilloscope traces of the beat signal of two DL DFB lasers. Upper trace: free running lasers, lower trace: Phase lock with mFALC.

Beat signal of two DL DFB lasers at 855 nm. Grey: free running lasers; blue: phase lock with mixing FALC to an external 10 MHz 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.
Downloads
- Product Brochure Scientific Lasers (please see website for latest specs!)
Literature
- Application Note: 12 orders of coherence control
- Scientific Publication: Y.N. Zhao et al., Sub-Hertz frequency stabilization of a commercial diode laser, Optics Comm. 283 (2010)
- Scientific Publication: F. Friederich et al., Phase-locking of the beat signal of two distributed-feedback diode lasers to oscillators working in the MHz to THz range, Opt. Express 18:8 (2010)
- Scientific Publication: F. Friederich et al., Hybrid continuous-wave demodulating multipixel terahertz imaging systems, IEEE Transact. Microwave Theory and Techn. 58:7 (2010)
Related Products
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- DigiLock 110: Versatile digital module for computerized locking tasks
- FPI 100: Fabry-Perot interferometer and detector unit
- Wavelength meters