A Quantum well laser is a type of semiconductor laser where the thickness of the active region is very narrow. The thickness of the active region determines the wavelength of the light emitted by the laser. These lasers have active regions of a thickness of about 100 Å. The emission wavelength is typically between 700 nm and 1600 nm for these lasers. The pulse duration of a light pulse ...read more

The goal of laser structures is to maintain a low threshold with high efficiency and a focused output beam. Gain guiding and Index guiding are two fundamental laser design strategies. A gain-guided laser is a type of laser in which the laser light is confined within the active medium rather than by external mirrors. Gain-guided lasers have a broad stripe geometry, where the active region span...read more

A Distributed Bragg Reflector (DBR) Laser is a semiconductor laser with a p-n junction as an active medium and contains one or two Bragg reflectors on each side of the active region. Bragg reflectors are gratings that act as mirrors or end reflectors with reflectivity optimized at a particular wavelength and it narrows the laser linewidth. In DBR, the grating is outside the active region where no ...read more

Pockels laser is a hybrid integrated laser made by integrating the pockels effect into a semiconductor laser. This laser has high-frequency modulation speed and fast switching by the integration of the electro-optic (EO) effect. It is the first multi-color laser in which the lasing occurs at infrared and visible frequencies by frequency doubling. It has narrow linewidth and wide tunability. T...read more

Spatial hole burning is a phenomenon that occurs in laser systems when several light beams pass through a laser medium with inhomogeneous absorption. It refers to the process wherein some areas of the medium experience a loss in gain, resulting in holes in the output beam. The performance of laser systems may be constrained by this phenomenon, especially when high optical power is desired. This ph...read more

Mode Locking is a technique to generate ultra-short pulses in the order of picoseconds (10-12) or femtoseconds (10-15). Lasers that generate a train of periodic ultra-short pulses are called mode-locked lasers. Laser light does not have a single, unmixed frequency or wavelength. All lasers emit light over a natural frequency spectrum or bandwidth.Figure 1: Mode-locked pulses by superposition of si...read more

Spectral hole burning is the frequency selective bleaching of the absorption spectrum of an optically active material. It is a phenomenon that occurs in certain types of optical materials such as glasses, crystals, and polymers, where the absorption spectrum of the material at a particular frequency is reduced or depleted as a result of exposing the material to intense light at that frequency. Thi...read more

The Ti:Sapphire laser (Ti:Al2O3 laser) is an efficient tunable solid-state laser that emits light in the visible and near-infrared region ranging from 650 to 1180 nm. This laser was first demonstrated by Peter Moulton in 1982 at MIT Lincoln Laboratory. A Sapphire crystal doped with Ti3+ ions act as the active medium for these lasers. The quantity of titanium ions within the host material is 0.1% a...read more

Gain switching is a method to generate short optical pulses in the order of picoseconds (10-12) in a laser by modulating the pump power or laser gain. An electrical or optical pumping can be provided for gain-switching. In this method, the optical cavity gain changes rapidly from a low value to a high value. When a high pump power is given, it takes time for the laser emission to happen since...read more

X-ray lasers are lasers that generate bright laser beams at discrete wavelengths ranging from 3.56 nm to 46.9 nm. A traditional gain medium cannot be used in x-ray lasers. They use a highly ionized plasma region created in a capillary discharge as the active medium and the plasma is created with a laser beam or with an electrical discharge. Mirrors that can reflect x-rays with normal incidence are...read more

Laser cavity modes are particular sets of standing wave patterns in a laser cavity. Specific resonant modes, often referred to as cavity modes, are supported by the laser cavity and are distinguished by their particular characteristics. These characteristics affect the laser's behaviour and are crucial for understanding and controlling the output of the laser. The properties of laser cavity mo...read more

A Free electron laser (FEL) is a light source that emits coherent electromagnetic laser pulses with short pulse lengths in the wavelength range from millimeters to x-rays depending on the electron energy. FEL was invented by John Madey in 1971 at Stanford University, and since then many FEL facilities have been constructed for various applications, including biomedical applications. The lasing med...read more

Laser cavity modes are particular sets of standing wave patterns in a laser cavity. Standing waves, also known as stationary waves, are created when two waves of the same frequency and amplitude but opposite phases interfere with each other. The output of a laser may consist of one mode or a superposition of several modes. These modes that are sustained depend on the boundary conditions, which are...read more

The Alexandrite laser is a tunable solid-state laser that uses a gemstone called alexandrite. Alexandrite is a common name for chrysoberyl (BeAl2O4) doped chromium (Cr3+) ions and is used as the active medium in this laser. The fundamental emission wavelength of this laser is 752 nm. The laser output can be tuned from 710 nm to 820 nm under optimum operating conditions. The output power of the las...read more