Femtolock 2

High Precision repetition rate stabilization

  • Ultra-low timing jitter
  • Hands-free operation
  • Maximum flexibility
  • Long term stability

Femtolock™ 2 is a sub-100 fs jitter synchronization unit for Element™ 2and Synergy™ ultrafast Ti:Sapphire oscillators. It allows locking of the round-trip frequency of oscillator pulses to a given reference RF-source. The use of multiple harmonics of the resonator round-trip frequency in combination with a simple and passively stable femtosecond laser resonator (based on Dispersive Mirror technology) enables the lowest jitter levels ever demonstrated in a commercial system.*

Maximum Flexibility

Access to the loop filter settings allows the user to optimize the timing jitter and to adapt to different applications. Femtolock 2 enables synchronization of the laser’s repetition rate by locking on the fundamental input RF-frequency, on one of its higher harmonics or to easily switch between the two. Optionally, a dual piezo configuration provides precise synchronization by simultaneously locking on both fundamental and harmonic of the input RF-frequency.

The Femtolock 2 can be custom designed to meet your specific requirements in terms of frequency and configuration.


The system is based on a combination of fast piezo translator(s) (PZT) and a wide range translation stage. This arrangement allows the Femtolock 2 to compensate for fast fluctuations (kHz), as well as for slow or medium long term drifts (e.g. temperature drifts).

The unique configuration ensures resonance-free synchronization up to high frequencies and guarantees a long term drift-free operation.

* Adapted from G.M.H. Knippels et al. “Two color facility based on a broadly tunable free-electron laser and a sub-picosecond-synchronized 10-fs Ti:Sapphire laser” Optics Letters, Vol. 23, No. 22, Nov. 15, 1998.


Synchronization to clock signals
Integrated Timing Jitter (1 Hz–1 MHz) <100 fs2  
RF Reference Input Requirements  
Frequency Range (nth harmonic of the repetition rate) 350 MHz–1.5 GHz3  
Input Level @ 50 Ohm 7 dBm  
User Interface (W x D x H) 16.65 x 15.48 x 3.5 in (423 x 400 x 89 mm) (19" 2U standard)  
Actuator(L x W x H) 1.97 x 0.98 x 1.97 in (50 x 25 x 50 mm)  
Detector Head(L x W x H) 1.97 x 0.79 x 1.18 in (50 x 20 x 30 mm)  

1. Due to our continuous improvement, all specifications are subject to change without notice.
2. The jitter cannot be smaller than reference source. Specification applies to Rainbow 2, Rainbow, Element and Synergy oscillators.
3. For synchronization to RF frequencies >1.5 GHz, please contact Spectra-Physics.

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Supporting Products

Product Description
Element 2
Ultrashort pulsed femtosecond oscillators
Ultra-broadband sub-10 fs Ti:Sapphire oscillator