69 Vertical Cavity Surface Emitting Lasers

As described above, quantum well heterostructure lasers have so many advantages, such as increased gain coefficient, that this form of laser is now the industry standard. The same advances in epitaxial growth technology that allows the practical exploitation of quantum well heterostructure lasers, have lead to the development of an entirely new class of semiconductor diode lasers called vertical cavity surface emitting lasers (VCSELs). In all of the conventional edge-emitting diode lasers...

610 Laser Arrays

For most of the gain-guided and index-guided laser structures described above it is possible to form multiple element arrays with the same processing technology. Simple arrays, consisting of a large number of decoupled elements distributed along a bar as shown in Fig. 6.22, can be utilized to obtain higher total output power than is available from a single element. Electrically, the structure is simply a number of identical diodes in parallel and the optical field pattern is a distributed array...

82 Fel Theory

The FEL is conceptually quite simple, consisting only of an electron beam, a periodic pump field, and the radiation field. The most common pump field is a static periodic magnetic field called a wiggler, but any field capable of producing a transverse electron oscillation could in principle be used. A typical configuration of the FEL is illustrated in the simple schematic diagram of Fig. 8.2. The wiggler field is perpendicular to the FEL axis, so electrons injected into the wiggler along the...

43 Visible Lasers In Liquid Mediaorganic Dye Lasers

Lasers in liquid gain media were first demonstrated in liquid solutions of organic dye molecules approximately 6 years after the discovery of the first laser. Dye lasers were developed to take advantage of the broad emission spectrum (radiating over a large wavelength range) typically available from such organic dyes. Such broad emission spectra had the potential to produce gain over a wide range of wavelengths, and thus to make possible very broadly tunable lasers. These laser gain materials...

31 Lasers In The Electromagnetic Spectrum

The term laser is an acronym for a radiation source based on light amplification by stimulated emission of radiation. The foundation for lasers was established with the first formulation of a quantum theory of light by Planck and Einstein.1 Later, the technological development of lasers was stimulated by the invention of various microwave devices, which led in the 1950s to microwave amplifiers based on stimulated emission of radiation (masers). The quest for the development of devices based on...

91 Principles Of Ultrashort Pulse Generation

Since the invention of the laser four decades ago, generating ever shorter laser pulses has always been one of the most important and active areas of laser physics and engineering. Numerous methods have been developed to generate ultrashort laser pulses. Rapid advances have been made, especially in the last decade during which optical pulses from various lasers have been pushed down to the femtosecond region, and the pulse peak power has reached the multi-terawatt level. In general, there are...

421 Lasers in Atomic Gases

Laser action in a mixture of helium and neon gases led to the first gas laser however, the visible laser transitions in that gas mixture were not among those first discovered. The well-known red He-Ne transition at 632.8 nm was discovered in 1962,1 nearly two years after the first laser. This laser has probably been used more than any other laser over the years, primarily because of its relatively low cost and compactness, high beam quality, low operating power requirements,...

W2 rtot 2NgndCTabso Pth 41p4

Where the ground state absorption loss Ngndaabsl has been added to the sum of the output coupler transmission and passive loss, Ttot, and we take Ttot < < 1. The lower laser level absorption can arise from either the equilibrium thermal population, or to a bottleneck effect, in which the relaxation rate of step 4 is slow compared to the stimulated emission rate. For the case where the lower laser level is precisely the same as the ground state, the system is three-level in nature, and...

24 Measurements And Calibration

FIGURE 2.7 The spectral response of a bare silicon detector, and of a silicon detector modified by a radiometric filter. (Adapted from Ref 14 with permission.) vantages of these detectors are their fragility they are extremely sensitive to mechanical shock, interference from electromagnetic fields, moisture, and temperature. Some are recommended for use at temperatures down to 45 C below ambient ( -20 C). Thus, in addition to the high-voltage supply, the PMT may require an external cooling...

94 Methods Of Pulse Width Measurements

To measure ultrashort optical pulses, special techniques and devices with picosecond to femtosecond time resolution are needed. They can be classified into electronic and optical techniques. References331 and 332 provide detailed discussions of ultrashort pulse measurements. Sampling Oscilloscopes. For a pulse strain of high repetition rate, the intensity envelope of optical pulses can be converted to electrical pulses by a fast photo-detector and displayed on a sampling scope. The width of the...

53 Solidstate Laser Materials

Solid-state lasers are based on a wide variety of insulating materials. All of these materials are conceptually similar, however, in that a laser-active center is incorporated into the solid referred to as the host. The host is an ionic solid (e.g., MgO) and the extrinsic laser center generally carries a positive charge (e.g., Ni2+). As a simple illustration of this situation, a two-dimensional view of the MgO Ni2+ system is pictured in Fig. 5.15. The small fraction of Ni2+ ions present at the...

422 Metal Vapor Lasers

Approximately 75 to 80 visible laser transitions have been reported in vapors of over 30 elements. These range from the first ion laser discovered, which was in mercury vapor where oscillation occurs in the red portion of the spectrum at 615.0 nm, to the helium-cadmium laser which oscillates at 441.6 nm at the blue end of the visible spectrum. Other well-known metal vapor lasers include the pulsed copper laser at 510.5 and 578.2 nm and the gold vapor laser at 627.8 nm. Pulsed visible lasers in...

7274

a Emission lifetime b Laser wavelength c Full-width d Gain cross section e Saturation fluence f Lower laser level energy above ground state. a Emission lifetime b Laser wavelength c Full-width d Gain cross section e Saturation fluence f Lower laser level energy above ground state. traction of energy from Nd YAG amplifiers without approaching the damage threshold of the optical elements 2Fsat is required . The two other transitions at 0.946 and 1.31 m also lase with reasonable efficiency,...