Solid state diode lasers

Rahavendran SV, Karnes HT. Solid-state diode laser-induced fluorescence detection in high-performance liquid-chromatography. Pharmaceutical Research 10, 328-334, 1993. 

The communications revolution also relies on a diverse set of CVD technologies. Some components are similar to those used in silicon microelectronics, but many are unique, involving complex epitaxial heterostructures of SiGe or compound semiconductor (e.g., AlGaAs) alloys that are required to yield high frequency (1-100 GHz) device operation. The communication revolution also relies on optoelectronic components, such as solid state diode lasers (another complex heterostructure device), and these devices are often grown by CVD. - Even the fiberoptic cables that transmit the optical component of the communications network are manufactured using a CVD technique to achieve the desired refractive index profile. ... 

A variety of laser sources have been applied to photodynamic therapy trials. These have included dye lasers (Coherent Lambda Plus, Santa Clara, CA or Laserscope Model 630, San Jose, CA) which use one source of laser energy (argon or KTP-YAG) to drive a dye (kiton red) to produce a red light. These laser systems usually require special power outlets and water cooling to function properly. Recently, a solid state diode laser has been produced (Diomed 630 PDT, Cambridge, UK) which can be operated from standard power outlets and can be air-cooled. This diode laser can supply up to 2 W of power at 630 nm, which is sufficient to activate porphyrin compounds. 

Tunable gas phase lasers are expensive. Less expensive solid-state diode lasers with wavelengths in the NIR are available. Commercial instmments using multiple diode lasers are available for NIR analyses of food and fuels. Because of the narrow emission lines from a laser system, laser sources are often used in dedicated applications for specific analytes. They can be ideal for process analysis and product quality control, for example, but are not as flexible in their applications as a continuous source or a tunable laser. 

A titanium-sapphire laser (CW Ti Sa, model 3900, Spectra Physics, Mountain View, CA) pumped by a solid-state diode laser, 532 nm (model Millenia Vs, Spectra Physics) was used to generate A.cx of 750 or 785 nm as described previously(/0, 77). For the detection of spores, all the measurements were performed in ambient conditions. For the detection of glucose, a small-volume flow cell was used to control the external environment of the AgFON surfaces. 

Sum-frequency mixing of two solid-state YAG lasers in a nonlinear crystal (see Ch. 20) to generate 589 nm in CW, CW mode-locked and macromicro pulse formats. The Nd YAG lasers can be pumped by flashlamps, but higher efficiency is obtained using diode lasers. 

Heterocyclic fluorophores based on the benzoxadiazole nucleous, namely 4-nitrobenz-2-oxa-l,3-diazole (NBD) 14 derivatives/analogs, have been widely used as derivatization reagents for analysis purposes. Examples include the amino- or thiol reactive 4-fluoro-7-nitrobenz-2-oxa-l,3-diazole (NBD-F) 15 and 4-chloro-7-nitrobenz-2-oxa-1,3-diazole (NBD-C1) 16 [45-50] and the thiol-reactive /V-((2-(iodoacetoxy)ethyl)-/V-methyl)amino-7-nitrobenz-2-oxa-1,3-dia-zole (IANBD ester) 17 [51] and 7-chlorobenz-2-oxa-l,3-diazole-4-sulfonate (SBD-C1) 18 [52], NBD-F and NBD-C1 derivatives can be excited at about 470 nm by using the relatively inexpensive and reliable argon ion lasers or newer diode pumped solid state (DPSS) lasers. NBD-F has been used as a labeling tag in various capillary electrophoresis (CE) experiments for amino acids [53-57] including the monitorization of in vivo dynamics of amino acids neurotransmitters [58]. 

N. Holonyak, Jr. and M. H. Lee, Photopumped III-V Semiconductor Lasers H. Kressel and J. K Butler, Heterojunction Laser Diodes A Van der Ziel, Space-Charge-Limited Solid-State Diodes P. J. Price, Monte Carlo Calculation of Electron Transport in Solids... 

Lasers and LEDs. Dye lasers pumped by Ar ion, Cu ion and frequency doubled Nd YAG solid state lasers. LEDs operating at 635-652, diode lasers at 635 (AlGalnP), 652 (InGaAlP) and 730 mn (AlGaAs). Solid state pulsed lasers, (e.g. Nd YAG, Nd YLF) operating at second, third and fourth harmonic generation. 

Chaos was also investigated in solid-state lasers, and the important role of a pump nonuniformity leading to a chaotic lasing was pointed out [42]. A modulation of pump of a solid-state NdPsOn laser leads to period doubling route to chaos [43]. The same phenomenon was observed in the case of laser diodes with modulated currents [44,45]. Also a chaotic dynamics of outputs in Nd YAG lasers was also discovered [46 18]. In semiconductor lasers a period doubling route to chaos was found experimentally and theoretically in 1993 [49]. 

Fig. 5. Schematics of an SPR/SPFS set-up. Typically, an He Ne laser with l — 632.8 nm is used. For the experiment in Section 4.7, an Nd YAG diode pumped solid-state (DPSS) laser with X — 473 nm is used.

Sources. The ultimate source for spectroscopic studies is one that is intense and monochromatic but tunable, so that no dispersion device is needed. Microwave sonrces such as klystrons and Gnnn diodes meet these requirements for rotational spectroscopy, and lasers can be similarly nsed for selected regions in the infrared and for much of the visible-ultraviolet regions. In the 500 to 4000 cm infrared region, solid-state diode and F-center lasers allow scans over 50 to 300 cm regions at very high resolution (<0.001 cm ), but these sources are still quite expensive and nontrival to operate. This is less trne... 

Raman Spectra. A Raman spectrum of the x XePtFg prepared in aHF, was recorded with a Halo Probe VPT System spectrometer (Kaiser Optical System, Inc., Ann Arbor, MI) using the 532 nm radiation of a Diode-Pumped, Solid-State (DPSS) Laser as exciting wavelength. It consisted of three lines at 657 cm (vs), 591 cm (s) and 480 cm (w). 

Although the first laser demonstrated was a solid state ruby laser, for many years the most common commercial systems were gas lasers such as helium neon lasers and argon ion lasers, or lasers based on organic dyes. Helium neon lasers were frequently limited in output power, argon ion lasers required expensive, sophisticated power supplies and cooling sources, and the dyes used in dye lasers were messy and often toxic. In the past decade, solid state lasers and diode lasers have become the dominant players in the commercial marketplace. 

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