LCC – Laser Coherence Control
- Modulation source for ECDLs and DFB lasers
- Controlled linewidth broadening / coherence reduction
- Coherence variation over more than three decades
- Adjustable linewidths up to GHz values
- For spectroscopy of Doppler-broadened lines
TOPTICA's laser coherence control module LCC is a stand-alone module designed to broaden the spectral profile of external-cavity or distributed feedback (DFB) diode lasers. Via a dedicated current modulation scheme, the linewidth of an ECDL or DFB laser is augmented, while its tuning properties are preserved. This allows the researcher to tailor the coherence length of a his laser to any value between 100 m and a few cm.
|Concept||Stand-alone modulation source with separate power supply|
|Maximum power||0.6 W (= 28 dBm) at 50 Ω|
|Attenuation||Adjustable via dip switch board, 0 .. -61 dB|
|Output bandwidth||10 .. 200 MHz|
|Allowed voltage standing wave ratio (VSWR) at output||1 .. ∞|
|Max. attainable linewidth|
Approx. 100 MHz for ECDLs
Typ. ~ 2 GHz for DFB lasers
|Applications||Spectroscopy of Doppler-broadened lines, amplifier seeding (avoiding non-linear effects)|
For use with TOPTICA’s tunable diode lasers, an AC modulation input is required on the laser head (DL-MOD PCB).
Mode spectrum of a DL DFB laser. Blue: 1 MHz linewidth without modulation, red: linewidth broadening to 900 MHz using the LCC.
Options & Related Products
Applications of the LCC include
- Spectroscopy of molecular absorption lines,
- Spectroscopy of Doppler-broadened atomic absorption lines,
- Optical pumping of metastable Helium-3 atoms (1083 nm),
- Seeding of high-power fiber amplifiers, avoiding nonlinear effects.
The LCC complements TOPTICA’s 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).