Aiming Laser Technology Co., Ltd.
Principles and Characteristics of Laser Modulation

Principles and Characteristics of Laser Modulation

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    Laser modulation is the process of encoding information onto a laser beam by altering one or more of its fundamental properties—such as amplitude, frequency, phase, or intensity. Owing to the excellent temporal and spatial coherence of lasers, they are ideal for high-speed, long-distance, and secure data transmission. Much like radio waves, laser beams are easy to modulate; however, due to their significantly higher frequency, they offer a much larger information-carrying capacity. Furthermore, the narrow divergence angle and high energy concentration of a laser beam make it suitable for applications ranging from optical communication to precision industrial processing.


    To support such diverse applications, Aimlaser provides a full range of high-performance solutions, including laser diode modules, fiber coupled laser modules, DPSS laser modules, and laser beam expanders, which are widely used in both research and industrial modulation systems.


    Principles and Characteristics of Laser Modulation


    Laser modulation classification

    Firstly, according to the relative relationship between modulator and laser, laser modulation can be divided into internal modulation and external modulation. Internal modulation means that the loaded modulation signal is carried out in the process of laser oscillation, and the oscillation parameters are changed according to the law of the modulation signal, so as to change the laser output characteristics and achieve the purpose of modulation. External modulation refers to loading the modulation signal after the laser is formed, that is, the modulator is placed outside the laser cavity, and the modulation signal voltage is added to the modulator to make some physical characteristics of the modulator change phase. When the laser passes through it, it is modulated. Therefore, the external modulation is not to change the laser parameters, but to change the parameters (intensity, frequency, etc.) of the output laser. External modulation is one of the most important modulation methods. Secondly, according to the working mechanism, they mainly include electro-optic modulation, acousto-optic modulation, magneto-optic modulation and direct modulation (also known as power modulation). Thirdly, it can be divided into amplitude modulation, frequency modulation, phase modulation and intensity modulation.


    Laser modulation principles

    Using laser as a tool to transmit information, we must first solve how to load the information signal into the laser radiation, that is, laser modulation. For example, the voice information transmitted by the laser is loaded into the laser, the laser "carries" the information to the photoelectric receiver through a certain transmission channel (atmosphere, optical fiber, etc.), and the receiver extracts the loaded voice information to complete the purpose of the call. Among them, laser is called carrier wave, so the information transmitted is called modulation signal. The electric field intensity of the laser light wave is, where AC is the amplitude, is the longitudinal phase angle, WC is the angular frequency, is the phase angle. Because the laser has parameters such as amplitude, frequency, phase and intensity, if one of its parameters changes according to the law of the modulated signal, the laser will be modulated by the signal to achieve the purpose of "carrying" information.


    Laser modulation characteristics

    First, the monochromaticity is good. The wavelength distribution range of the light emitted by the laser is narrow, so the color is very pure. The monochromaticity of laser is much stronger than that of other monochromatic light sources. Good monochromaticity can facilitate filtering and improve signal-to-noise ratio. In material processing, the absorption spectra of different materials are different, and the monochromaticity of the laser can well control the absorption depth and distribution. Materials can be processed selectively and controlled. Monochromatic light is much more convenient in optical design. There is no dispersion difference, and the better the monochromaticity, the more stable the corresponding wavelength or frequency.


    Second, it has good temporal and spatial coherence. Laser is very different from ordinary light. Because its frequency is very simple, the light emitted from the laser can propagate in the same direction step by step. They can be converged to a point with a lens to highly concentrate the energy and send it to the optical fiber, which is called high coherence. The volume of semiconductor laser used in optical fiber communication is very small, which is similar to that of ordinary crystal triode. Its optical power is generally not too large, usually only a few milliwatts. If its energy is highly concentrated, it can be easily coupled into the optical fiber. This is of great significance to increase the relay distance of optical fiber communication and improve the communication quality. The directivity of laser is much better than that of all other light sources. It is almost a beam of parallel lines. Ordinary light sources always radiate in all directions, which is necessary as lighting. But to concentrate this light at one point, most of the energy will be wasted and the efficiency is very low. Most of the light emitted by the semiconductor laser is very concentrated, and it is easy to enter the end face of the fiber.


    Recommended Products for Laser Modulation Applications

    To meet various technical requirements in communication, processing, and experimental research, AIMING LASERS recommends the following laser products:

    • Laser Diode Modules for sale: Available in red, green, blue, and infrared wavelengths; suitable for direct modulation and internal modulation applications.

    • DPSS Laser Modules: Provide high coherence and low noise, making them excellent for high-precision external modulation.

    • Fiber Coupled Laser Diode Modules: Engineered for efficient fiber injection, these modules are key components in laser modulation and transmission systems.

    • Laser Beam Expanders: Enhance beam collimation and stability, supporting precise external modulation setups and beam delivery in lab and industrial environments.

    Laser modulation is a foundational technology in modern optoelectronics, enabling secure, fast, and efficient data transmission. Whether you're working on advanced optical communication systems, laser-based measurement, or industrial processing, AIMING LASERS provides a complete line of reliable, high-performance laser products.

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