Published 15/05/2024

 A low phase-noise and ultra-low timing-jitter laser source is uniquely suited to address interesting applications such as photonic analog-to-digital conversion (ADC), generation of radio-frequency (RF) signal, optical frequency comb and timing synchronization. The wider impact of these applications includes techniques for detection of greenhouse gases, water vapour measurements, highly-secured data transmission and communication, as well as deep space tracking missions.

RF sources are widely used in our modern world, for example in radar systems, GPS and wireless communication methods such as 4G, 5G and 6G into the future. RF sources in the range of megahertz to gigahertz frequencies have widespread uses. Although the usage of quartz oscillators remains widespread, there exists a growing demand for higher purity RF signal —that is, extremely low jitter and a high phase stability especially with the increasing trend of photonics replacing electronics in more and more functions.

Figure 1 — Schematic of the photonic low-noise RF generator (blue box) using the MENHIR-1550 laser as photonic source. The output RF frequencies are defined by two factors: the oscillator (laser) fundamental frequency and the optical to RF converter bandwidth. The optical output can serve to disseminate the RF signal to a distant location from the local oscillator. The transmission of a RF signal via optical fiber provides significantly higher performance than traditional bulky and stiff RF waveguides.

With the use of the laser source described above in conjunction with a high-quality photodiode, the excellent phase-noise performance is transferred to the RF output, outperforming any quartz-based RF generator(Figures 1 –3).This method is described as the photonic solution. As an added advantage, the photonic solution enables the optical signal to be distributed over hundreds of meters with no loss using optical fiber as compared with inefficient and expensive RF waveguides, even in harsh environments, thus allowing the RF signal to be generated where it is needed. Some scenarios where it is advantageous to transfer the signal over long distance while ensuring low-loss and low-jitter include network synchronization for telecommunications, precision radar for both civil and defence, as well as for scientific experiments which requires timing distribution systems to deliver the RF signal to particle accelerators for generation of high brightness ultrafast X-ray sources driven by free electron lasers (FEL).

Figure 2—Phase noise (top) and timing-jitter (bottom) of the MENHIR-1550 laser-based RF generator, measured on the 10th harmonic signal (10 GHz). The black dashed line represents the detection limit of the characterization setup and does not represent the intrinsic limit of the laser.

There is one such company able to deliver the laser requirements above –Menhir Photonics, a laser company based in Switzerland. The low-noiseMENHIR-1550 ultrafast laser with 1 to 2.5GHzpulse repetition rate by Menhir Photonics is culmination of decades of expertise from the ultrafast laser field. Contrary to past large systems using Ti:Sa crystals, Menhir Photonics pushed the technology to its limits to offer an oscillator in a shoebox-sized case(Figure 4),thus making this technology more accessible to a wider range of customers.

Figure 3 — Typical RF output from a photonic solution.

Figure 4 —The MENHIR-1550 is a proven, turnkey industrial grade laser, all in a compact footprint of 260mmx 250mmx 60 mm, compactible with 1U rack mounting. OEM version hold all inputs/outputs on the back.

For future outlook, there is a validated path to deliver higher repetition rates of up to 10GHz in a butterfly package, thus further shrinking the size of comb lasers. As the trend of photonics replacing electronics in more functions gains traction, the demand for a rugged, industry-grade ultrafast and ultra-low noise laser with turn key operation from Menhir Photonics is only projected to increase over time. Please take the time to browse more information about Menhir Photonics at this webpage https://menhir-photonics.com/, or get in touch with our sales team at sales@optosigma-sea.com for further assistance.