English

Shanghai Optics and Machinery Institute has made progress in femtosecond fiber lasers based on twisted Sagnac interferometer mode locking

1229
2024-04-22 16:17:22
See translation

Recently, the research team of the Aerospace Laser Technology and System Department of the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, proposed a torsional Sagnac interferometer and applied it to the fiber laser system, realizing mode locking self starting and pulse shaping. The relevant research achievements were published in the Journal of Lightwave Technology under the title of "Femtosecond fiber laser mode locked by a twisted Sagnac interferometer".

Fiber optic Sagnac interferometers have been widely used in fields such as navigation, sensing, and lasers. The common path structure of Sagnac interferometer has both advantages and disadvantages. One is that precise length control is not required between optical paths, which is crucial for robust interferometric measurements. The second issue is that the transmittance of the Sagnac fiber loop is fixed and cannot be freely tuned. 
Therefore, traditional nine cavity mode-locked fiber lasers based on Sagnac fiber interference loops face the problem of inflexible mode locking.

In this study, researchers proposed a twisted Sagnac interferometer with continuously adjustable phase bias. By introducing 90 ° fusion in the Sagnac loop and utilizing the birefringence of polarization maintaining fibers, linear phase shift differences in clockwise and counterclockwise directions can be introduced and adjusted. When applied in a nine cavity fiber laser system, setting an appropriate transmittance can achieve mode locking self start. The experimental results show that by stretching the fiber to change the linear phase shift difference, the laser can achieve switching between different operating modes. By optimizing the phase shift difference, laser pulses with a spectral bandwidth of 31nm and a pulse duration of 160 fs can be generated at a repetition frequency of 24.5 MHz.

This study achieved real-time continuous adjustment of the transmittance of Sagnac fiber optic interference ring, providing greater flexibility and control for the nine cavity mode-locked laser, and improving its application prospects in optical metrology and sensing fields.
This work was supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences, the National Natural Science Foundation of China, and the Shanghai Natural Science Foundation.

Figure 1 Schematic diagram of a twisted fiber Sagnac interferometer.

Figure 2: Experimental setup diagram of femtosecond fiber laser based on twisted fiber Sagnac interferometer mode locking.

Figure 3 Spectral tuning and time-domain characteristics under different clockwise and counterclockwise linear phase shift differences and nonlinear phase shift differences.

Source: Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences

Related Recommendations
  • NASA plans to use lasers to measure the impact of exhaust gases on the lunar surface during landing, in order to plan lunar landings more effectively

    Recently, NASA's official website showed that a research team at the University of Central Florida has tested an instrument called Ejecta STORM, which aims to measure the size and velocity of surface particles generated by exhaust gases from rocket powered landers on the moon or Mars.According to NASA, when a spacecraft lands on the moon or Mars, rocket exhaust plumes can produce efflorescent ejec...

    2023-10-31
    See translation
  • Deere Laser's self-developed laser induced sintering technology, with LIF equipment orders exceeding 100GW in production capacity

    Recently, Deere Laser received mass production orders and bid confirmations for laser induced sintering (LIF) equipment from multiple top customers, with a cumulative production capacity exceeding 100GW.As an innovative technology iteratively developed by the company based on its own LIR technology and LIA technology, LIF technology has won industry recognition for its excellent efficiency improve...

    2023-09-18
    See translation
  • The official launch of FV4000 and FV4000MPE microscopes aims to redefine scientific imaging

    Introduction to FLUOVIEW ™ The FV4000 confocal laser scanning microscope and FV4000MPE multiphoton laser scanning microscope have made breakthroughs in imaging technology, enabling researchers to make new scientific discoveries. The FV4000 and FV4000MPE microscopes aim to redefine scientific imaging, providing higher accuracy, lower noise, and higher sensitivity, setting new standards for im...

    2023-11-03
    See translation
  • Phil Energy from South Korea wins mysterious order from European battery manufacturer

    Recently, Phil Energy, a South Korean secondary battery equipment manufacturer, successfully won an order from a European battery manufacturer to manufacture the next generation 46 series cylindrical battery manufacturing equipment. At present, both parties have signed a supply agreement for this cooperation, but have not disclosed the customer name and order size to the public. It is understood...

    2024-07-25
    See translation
  • Atomstack Maker A5 V2: A laser engraving machine suitable for beginners

    In the recent DIY field, innovative and increasingly affordable laser engraving machines have emerged, mainly designed for first-time users in this field. A particularly noteworthy example in this regard is the Atomstack Maker A5 V2 model. This device is known for its versatility and ease of use, making it an ideal choice for beginners in the world of laser engraving.The Atomstack Maker A5 V2 is a...

    2024-01-03
    See translation