PRECISION MICROWAVE GENERATION
In the last years the demand for ultra-low noise microwave (MW) and radio-frequency (RF) signal sources increased drastically. Standard industrial applications and high-end academic experiments require ever higher precision:
- Radar systems
- Defence communications
- Photonic ADC
- Ultra-stable clocking
- Test and measurement
- Satellite communications
- Particle accelerators, FELs
- Coherent communications
Ultra-low phase noise generation from modelocked lasers offers a simple solution to achieve RF or MW signals with sub-femtosecond RMS timing jitter. Ultra-low noise quartz oscillators show phase noise higher by orders of magnitude. Cryogenically cooled sapphire oscillators on the other hand require an extensive cooling system, which limits their range of application due to their complexity. Although, the more recently developed ultra-low noise microwave signal generation from optical frequency comb based system can achieve extremely high phase stability and low phase noise, the installation and maintenance of these systems are technically difficult and cost intensive .
For many high performance applications in signal processing and communications (sampling clocks, ADC, master oscillators for signal source analyzers) high frequency phase noise and accumulated timing jitter impact the system performance most critically. For these applications, one may generate microwave directly from a free-running modelocked laser by simply using a photodiode signal and optional electronic amplification. To suppress the phase noise at lower noise frequencies, one may lock or synchronize the modelocked laser to a low-noise and electronic oscillator  for long-term stability. For applications, that require a high frequency microwave reference oscillator (e.g. 10 GHz) it may also be a solution to synchronize a low-noise voltage controlled oscillator to a modelocked laser .
Menhir Photonics added values
Menhir Photonics offers modelocked lasers with the lowest phase-noise available on the market today combined with extreme reliability. Fig. 1 shows a typical phase noise measurement for a free-running laser of the MENHIR-1550 series, measured on the 10 GHz carrier i.e. the 40th harmonics (250 MHz pulse repetition rate). Note that the noise floor of the measurement limits the integrated timing jitter to approximately 500 as (attoseconds).
Fig 1.: 1) Phase noise power spectrum of a free-running MENHIR-1550 250MHz laser measured at the 10 GHz harmonics. 2) Integrated timing jitter starting at 10 MHz for the same free-running laser.
All lasers of the MENHIR-1550 SERIES have an optional fast repetition rate tuning with a modulation bandwidth of >50 kHz for repetition rate locking or synchronization. In addition, there is also the option for fast modulation of the pump current.
The MENHIR-1550 SERIES reaches unmatched levels of industrial quality and environmental stability. It has been excessively tested for vibrations, shocks and other external disturbances (space and aerospace related standard tests). For integration into space-critical applications, customized small-sized versions are available.
 Portuondo-Campa, G. Buchs, S. Kundermann, L. Balet, S. Lecomte, "Ultra-low phase-noise microwave generation using a diode-pumped solid-state laser based frequency comb and a polarization-maintaining pulse interleaver", Opt. Expr. 23(25), 32441-32451 (2015)
 Schlatter, B. Rudin, S. C. Zeller, R. Paschotta, G. J. Spühler, L. Krainer, N. Haverkamp, H. R. Telle, and U. Keller, ”Nearly quantum-noise-limited timing jitter from miniature Er:Yb:glass lasers”, Opt. Lett. 30, 1536 (2005)