It is also possible to directly generate high powers (> 10 W) with a broad-area laser diode having a surface Bragg grating within its resonator. Output powers well above 100 mW can be achieved with such devices. The actual DBR laser is then the seed laser. There are MOPA structures where an additional amplifier section (a semiconductor optical amplifier) is placed on the same semiconductor chip. Due to the relatively short laser resonator, it is larger than that e.g. The linewidth of a DBR diode is typically a few megahertz. There are more sophisticated device designs, exploiting a kind of Vernier effect with sampled gratings ( SG-DBR laser), that offer a tuning range as wide as e.g.
#LASER GRATING FREE#
Mode-hop free tuning over a larger wavelength region is possible by coordinated tuning of the Bragg grating and the gain structure. Electro-optic tuning can also be accomplished. If the temperature of the whole device is varied, the wavelength response is significantly smaller than for an ordinary single-mode laser diode, since the reflection band of the grating is shifted less than the gain maximum.
be electrically heated, or simply by varying the temperature of the gain region via the drive current. Tuning within the free spectral range of the laser resonator may be accomplished with a separate phase section, which can e.g. Another section of the laser waveguide acts as the amplifying medium (active region), and the other end of the resonator may have another DBR.ĭBR laser diodes are usually single-frequency lasers with diffraction-limited output, and often they are wavelength-tunable (→ tunable lasers). DBR Laser DiodesĪ DBR laser diode contains some corrugated waveguide structure (a grating section) providing wavelength-dependent feedback to define the emission wavelength.
Most solid-state bulk lasers actually also use laser mirrors which are Bragg mirrors nevertheless such lasers are not called DBR lasers.Ī DBR laser is different from a distributed feedback laser, where the whole active medium is embedded in a single distributed reflector structure. Lasers of DBR type are usually laser diodes, but the term is also sometimes used for fiber lasers containing fiber Bragg gratings. In most cases, the Bragg mirror is more specifically a quarter-wave mirror, providing the maximum amount of reflection for the given number of layers. A DBR is a Bragg mirror, i.e., a light-reflecting device (a mirror) based on Bragg reflection at a periodic structure.
#LASER GRATING HOW TO#
How to cite the article suggest additional literatureĪ distributed Bragg reflector laser is a laser, where the laser resonator is made with at least one distributed Bragg reflector (DBR) outside the gain medium (the active region). Definition: lasers containing distributed Bragg reflectors as end mirrorsĬategories: fiber optics and waveguides, optoelectronics, laser devices and laser physics
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