Laser diode arrays

Figure 7.3. Schematic of Nd YAG laser, pumped by an arc lamp or diode laser array. Doubling crystal converts 1064 nm light to 532 nm.

Besides their applications as tunable light sources, diode lasers are more and more used as pump lasers for tunable solid-state lasers and optical parametric amplifiers. Monolithic diode laser arrays can now deliver up to lOOWcw pump powers [5.124]. 

The future importance of these lasers is derived from the fact that many of them may be pumped by diode laser arrays. This has already been demonstrated for Nd YAG and alexandrite lasers, where very high total energy conversion efficiencies were achieved. For the diode laser-pumped Nd YAG laser, values of rj = 0.3 for the ratio of laser output power to electrical input power have been reported (30% plug-in efficiency) [5.132]. 

N.W. Carlson Monolythic Diode Laser Arrays (Springer, Berlin, Heidelberg, New York 1994)... 

The future prospects for selective chemistry research as an aspect of laser development are not as bright as several years ago. With the exception of the quest for a visible chemical laser, most new laser research is oriented towards systems that are patently nonmolecular. The leading candidate for very high power applications is the free electron laser (PEL). In this device, the interaction of a relativistic electron beam with a periodic magnetic structure produces coherent radiation. Such devices on paper can have substantially higher power and efficiency than electric molecular lasers. For moderate power applications, advances in solid state lasers, nonlinear optical conversion processes, and tunable solid state media offer the prospect of broadly tunable compact sources. At low powers, diode lasers and diode laser arrays are gaining increasing application and hold out the promise, when used with solid state media, of versatile tunable sources. 

Photodiode detectors have already been cited in this chapter in relation to near-IR fluorescence measurements on singlet oxygen,(8 16 18) in decay-time temperature sensing,(50) in liquid chromatography,(62) the study of proteins labelled with Nile Red,(64) and diode laser spectrometry,(67) Photodiodes are also conveniently packaged for many applications in an array form enabling rapid data acquisition e.g., in spectrophotometry, (35)... 

As early as 1982, a diode laser-pumped miniature NdtYAG laser with a linewidlh of less lhan 10 kHz. was demonstrated. The research in this area continued apace at Stanford University and by a numher of commercial electronics limis. w ith emphasis placed on ihe development of three-level lasers. Q-switched and mode-locked operation, single-frequency operation (monolithic nonplanar ring oscillator), visible radiation by harmonic generation, and array-pumped solid-slate lasers. See Fig. ft. 

Fig h. Diugr.i ii dI high-average power slab laser oscillator pumped by an array of diode lasers. Such an arrangement offers lower com, ease of power scaling, and long-ierm reliability. i Alter H er I... 

Arrayed microlenses are widely used in a variety of applications that involve miniaturized optical components.172 For example, they can be found at the heart of optical communication systems, facsimile machines, laser printers, and many other kinds of digital information storage or processing devices. In all these applications, the arrayed microlenses simply serve as diode laser correctors, fiber-optic couplers or connectors, and optical scanners. In a set of recent publications, Whitesides and coworkers have also demonstrated that arrayed microlenses could be used as a new platform for photolithography, through which submicrometer-sized structures could be conveniently fabricated as patterned arrays by reducing mm to cm scale features on a photomask.157... 

An alternative to the arc-lamp-pumped Nd YAG, which is attractive to analytical applications, is the diode-pumped NdrYAG laser, introduced in the early 1990s. An array of diode lasers operating in the range of 800 to 900 nm is directed at the Nd YAG rod, and pumps the Nd to its excited state. Diode lasers are more efficient and compact than arc lamps, and a much larger... 

Optical patternation is a nonintrusive technique based on extinction tomography utilizing diode lasers to form laser sheets and linear photo diode arrays as... 

Here, we show how an array of diode lasers are arranged in a stack so that they can be used to generate very high optical power. What we have not shown is the details of the active layer comprising the individual diode lasers. This is shown in the following diagram ... 

The Construction of a Single Diode Laser in a Laser Array... 

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