From Understanding Lasers

The simplest type of diode laser resonator is the Fabry Perot cavity introduced in Chapter 3, a linear cavity with flat mirrors on the two ends. In a semiconductor laser, the linear cavity is the active stripe in the junction layer, and the flat mirrors are the facets on the edges of the chip. Typical diode laser resonators are only 300 to 500 micrometers long, but diode lasers have high gain, so milliwatt powers are easy and much higher powers are possible.

The cavity mirrors are formed by the boundary between the semiconductor crystal and the air. The refractive index of GaAs is 3.34 at 780 nm so according to Equation 5-4 roughly 30% of the light hitting the boundary is reflected back into the semiconductor, providing adequate feedback for laser oscillation.

A diode laser with such a simple cavity emits light from both facets. In practice, one facet is coated to reflect all or most of the incident light, and the beam emerges from the other facet. Light emerging from the rear facet can be monitored to control laser operation in devices such as fiber-optic transmitters.

Narrow-stripe lasers typically emit from an area less than a micrometer high and...


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Products & Services
Lasers
Lasers are devices that produce intense beams of monochromatic, coherent radiation. The word "laser" is an acronym for Light Amplification by Stimulated Emission of Radiation.
Etalons
Etalons are two flat glass plates separated by a parallel spacer, with the inner surfaces of the plates coated with a partially reflecting layer.
Diode Lasers
Diode lasers use light-emitting diodes to produce stimulated emissions in the form of coherent light output. They are also known as laser diodes.
Fiber Optic Amplifiers
Fiber optic amplifiers re-amplify an attenuated signal without converting the signal into electrical form.
Fiber Lasers
Fiber lasers use optical fibers doped with low levels of rare-earth halides as the lasing medium to amplify light.

Topics of Interest

9.6.2 Distributed Feedback Lasers Applications such as high-speed data transmission in fiber optics require limiting laser emission to a narrower range of wavelengths than possible with a Fabry Perot...

9.14 WHAT HAVE WE LEARNED? Semiconductor lasers are often called diode lasers or laser diodes. Diodes are two-terminal electronic devices that conduct current in one direction. Electrons in the...

9.10.2 Bandwidth and Modes Earlier sections have mentioned the oscillating modes of various types of diode lasers, but it is worth looking at them again and how they affect the spectral bandwidth of...

9.5.1 Gain- and Index-Guided Lasers Stripe width can be limited in two ways: by restricting the flow of current to a narrow stripe, or by fabricating stripes of material with different refractive...

2.5 New Research Directions and Outlook 2.5.1 Single-mode devices The lasers described in the previous sections employed a multimode Fabry-Perot cavity; therefore, single-mode operation is observed...