Does a multimode laser emit one wavelength, or multiple wavelengths?

Multimode lasers emit only one wavelength, and the wavelength cannot be changed.

Laser mode, one of the most important indicators to measure the quality of laser, can be divided into basic mode and multi-mode. The fundamental mode is the TEM00 mode, which has an index of 0 in both the X and Y axes, which is an ideal dot, and the smallest beam diameter can be obtained with the laser of the TEM00 mode. Multimode, on the other hand, is non-0 exponential in both the x and y directions, and its beam quality is poor, so it is generally only used for heat treatment and welding.

The wavelength emitted by the laser is determined by the substance inside the laser that produces the laser, for example, the wavelength of the CO2 laser is determined by the CO2 energy level transition radiation, and its wavelength is 1064um. Moreover, the wavelength of the laser is not adjustable outside the laser.

The difference between a multi-mode laser and a single-mode laser is like the difference between a shotgun and a pistol. The wavelength is determined by the laser diode itself, and the deeper point is determined by the crystal of the semiconductor PN junction. The original wavelength of the laser diode can be changed by adding crystals to the front.

Any single-mode (single-wavelength) laser diode refers to a very narrow band spectrum, and the performance of the laser diode is to see whether this band spectrum can be made very narrow.

Single-mode vs. multimode is a concept of the mode of transmission of electromagnetic fields, independent of wavelength.

Is a laser monochromatic light with only one wavelength? Or is the wavelength in a very narrow range?

A multi-mode fiber laser means that the output fiber is multi-mode fiber; A multi-wavelength fiber laser is one in which the output wavelength is multiple wavelengths and is output from a single fiber.

Adjust the frequency.

Strictly speaking, lasers cannot have the same frequency for every photon, so the wavelength is not a fixed value.

Types of lasers.

Wavelength (nm).

Argon fluoride laser (ultraviolet light).

193 Krypton fluorine laser (ultraviolet light).

248 xenon chloride laser (ultraviolet light).

308 nitrogen laser (ultraviolet light).

337 argon laser (blue light).

488 argon laser (green light).

514 HeNe laser (green light).

543 HeNe laser (red light).

633 rhodamine 6 g dye (dimmable).

Ruby (cralo3) (red light).

694 neodymium-yttrium aluminum garnet (near-infrared).

Carbon dioxide (far-infrared light).

Beijing Huayuan Tuoda Laser Technology (hereinafter referred to as "HYTD"). HYTD manufactures pigtail diode lasers with single-mode, polarization-maintaining, and multimode fiber outputs, and small diode lasers in standard TO packages (TO56, TO38, TO9). The laser wavelength range is from 375nm-1650nm, such as:

Blue-violet lasers: 375nm 405nm blue lasers: 450nm 457nm 473nm green lasers:

532nm；Yellow laser: 589nm; Red laser: 635nm, 660nm, 660nm, 670nm, 671nm; Infrared lasers: 808nm, 914nm, 946nm, 980nm, 1047nm, 1053nm, 1064nm, 1320nm, 1342nm, 1550nm, 1650nm.

The wavelength and output power can be selected according to the customer's needs.

The 1064nm laser is an ND:YAG laser, which is a solid-state laser, and the infrared fiber laser usually refers to the doped fiber laser, which is a pump light that adds 980nm to 1480nm.

If nd:yag is used as the working material of the fiber laser, it will emit light at 1064nm, which is the nd:yag fiber laser.

The wavelength of the laser is determined by the energy level distribution of the laser gain material, so look for this book on the principles of lasers.

Single-mode ones are generally 1310nm, 1490nm, 1550nm, etc.

1) Large communication capacity and long transmission distance; The potential bandwidth of one fiber can reach 20thz. With such a bandwidth, it only takes about a second to transmit all the written data of human beings, ancient and modern, Chinese and foreign. At present, the 400Gbit S system has been put into commercial use.

The loss of optical fibers is extremely low, and at the vicinity of the wavelength of light, the loss of quartz fiber can be lower, which is lower than the loss of any current transmission medium. As a result, the transmission distance without a relay can be several times.

10. Even hundreds of kilometers. (2) Small signal interference and good confidentiality performance; (3) Anti-electromagnetic interference, good transmission quality, electrical communication can not solve all kinds of electromagnetic interference problems, only optical fiber communication is not subject to all kinds of electromagnetic interference. (4) The optical fiber is small in size and light in weight, which is easy to lay and transport; (5) The material is abundant, the environmental protection is good, and it is conducive to saving non-ferrous metal copper.

6) No radiation, difficult to eavesdrop, because the light waves transmitted by the optical fiber cannot escape outside the optical fiber. (7) The optical cable has strong adaptability and long life.

In the theory of optical fiber communication, optical fiber is divided into single-mode and multi-mode, and the difference is as follows:

1.Single-mode fiber has a small core diameter (about 10mm), only allows one mode transmission, has small dispersion, works at long wavelengths (1310nm and 1550nm), and is relatively difficult to couple with optical devices.

2.Multimode fiber has a large core diameter (m or 50mm), allows hundreds of modes to transmit, has large dispersion, and works at 850nm or 1310nm. Coupling with optical devices is relatively easy.

For optical end modules, strictly speaking, there is no distinction between single-mode and multi-mode. The so-called single-mode and multi-mode modules refer to the optical components used in the optical terminal module and what kind of optical fiber can be used to obtain the best transmission characteristics.

In general, there are the following differences:

1.Single-mode modules generally use LD or LEDs with narrow spectral lines as the light source, and the size of the coupling parts is well matched with the single-mode fiber, and it can transmit long distances when using single-mode fiber transmission.

2.Multi-mode modules generally use ** low LED as the light source, and the size of the coupling parts is well matched with the multi-mode fiber.

Single-mode fiber outputs a pattern of optical signals, which usually means one wavelength of optical signals, and multimode is multiple wavelengths of optical signals. Single-mode and multi-mode use different low-loss communication windows, multimode is generally 850nm, single-mode is 1310nm or 1550nm, especially 1550nm, only one wavelength is allowed to pass through, this book.

Upstairs is not right, the concept of fiber is different from that of other lasers. There are many modes in the optical fiber, transverse mode Te, transverse magnetic mode TM, in addition to mixed mode EH mode, mixed mode HE mode, etc. The single-mode in the optical fiber is similar to the concept of the single-cross-mode of ordinary lasers, with concentrated cross-sectional spots and the largest power density, while multimode means that the spots are relatively scattered.

Optical fiber is a passive transmission medium, divided into single-mode and multi-mode optical fiber.

First of all, it is necessary to understand that the laser mode is divided into horizontal mode and longitudinal mode, why should it be distinguished? Because the two are fundamentally different!

1. Longitudinal mode: Longitudinal mode refers to the stable standing wave form formed in the laser resonator! There will be many standing wave forms in the same resonator, because there are many phase matching conditions in the cavity, as long as this condition is met, a stable standing wave can be formed (the amplitude condition is ignored here, we assume that the gain spectrum in the active region of the laser is very wide), and a standing wave form corresponds to a longitudinal mode!

To understand the longitudinal mode, the subject can relate it to the laser wavelength, which you can simply understand as a wavelength corresponding to a laser longitudinal mode mode.

2. Transverse mode: Transverse mode refers to the distribution of the laser field (including electric field and magnetic field) on the cross-section perpendicular to the direction of laser propagationFor example, the distribution of the basic mode in the cross-section is a spot in the cross-section, and the higher-order mode has multiple spots in the cross-section!

Note that when you see a spot on the cross-section, the fundamental mode, it doesn't have to be a single longitudinal mode!

3. Single-mode and multi-mode: I default to the subject here talking about the longitudinal mode, because what we usually call single-mode and multi-mode refers to the longitudinal mode, and the horizontal mode says the basic mode and the higher-order mode!If you relate the laser wavelength to the longitudinal mode as I said earlier, the difference between single-mode and multi-mode is obvious!

Single-mode means that the laser outputs only one wavelength of light, and in multi-mode, the output light of the laser contains multiple wavelengths!

The output wavelength of a fiber laser is determined by the gain medium, that is, what kind of doped fiber is used, and the two most common wavelengths are 1064nm and 1550nm, respectively.

Typical ER3+-doped fiber lasers are tuned at 1 536 nm and 1 550 nm

Taking an ND3+-doped quartz fiber laser as an example, an Algaas (aluminum-gallium arsenic) semiconductor laser with a wavelength of 808nm is used as the pump source, and the laser emission wavelength of the fiber laser is 1064nm.

Fiber laser refers to the laser with rare earth element glass fiber as the gain medium, fiber laser can be developed on the basis of fiber amplifier: under the action of pump light, it is easy to form a high power density in the optical fiber, resulting in the laser energy level of the laser working substance "particle number reversal", when the positive feedback loop (forming a resonator) can be formed laser oscillation output.

It depends on what kind of laser you are, if it is a MOPA structure, it is a seed source plus amplifier, the output wavelength is determined by the seed source, what wavelength is the seed source, and what wavelength is the output of the fiber laser. If you build your own fiber laser, it is determined by your resonator, if you use a grating as a resonator, the output wavelength is related to the grating.

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The color of light is determined by the wavelength of the light, and the light output by the laser has a narrow wavelength range and is extremely pure.