Tapered photonic crystal quantum cascade laser and manufacture method thereof

Abstract

The invention discloses a tapered photonic crystal quantum cascade laser for outputting near-diffraction-limited beams and the manufacture method thereof. The laser comprises a substrate, as well as a lower waveguide layer, an active area, an upper waveguide layer, an upper cover layer, an upper contact layer, an ohmic contact layer, an electrical insulation layer, a front side electrode and a rear side electrode on the substrate. The laser has the ridge-shaped mesa double-grooved waveguide structure, wherein the ridge-shaped mesa structure includes a main control oscillation area with a uniform ridge width and a gain amplification area with a tapered structure. The photonic crystal structure is used for providing a distributed feedback waveguide manufactured between the upper contact layer and the ohmic contact layer. The tapered photonic crystal quantum cascade laser can acquire singe-mode near-diffraction-limited beam output. The waveguide structure with the combination of the ridge-shaped mesa and the tapered gain amplification area can greatly reduce the far-field divergence angle, thereby improving the output power while obviating the heat dissipation problem that is difficult to avoid for the similar wide-ridge large-power devices.

Description

technical field [0001] The invention relates to the technical field of semiconductor optoelectronics, in particular to a high-power, near-diffraction-limited light output photonic crystal quantum cascade laser and a manufacturing method thereof. Background technique [0002] In 1994, Bell Labs first invented the quantum cascade laser working in the far infrared band. It is different from the traditional semiconductor laser. The quantum cascade laser is a unipolar device that only relies on the energy levels between subbands to participate in electronic transitions. People can pass Ingenious energy band structure design, without changing the material system, can adjust the lasing wavelength arbitrarily within a certain band range, breaking through the limitation that the lasing wavelength of traditional semiconductor lasers must depend on the band gap width of the material, and greatly expanding human The spectral range that can be used, therefore, the quantum cascade laser i...

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Problems solved by technology

[0003] In order to meet the applications in the above various fields, quantum cascade lasers are required to work in room temperature continuous wave single-mode, but so far, only a few quantum cascade lasers with individual wavelengths have achieved room temperature continuous wave single-mode operation. Quantum cascade lasers all use technologies such as electron beam exposure, buried grating, and secondary MOCVD epitaxy, which are not only expensive but also technically complex, which makes the development process of quantum cascade lasers extremely difficult, which is not conducive to improving device reliability and realizing mass production

The method of using the top grating (evenly distributing the grating on the top of the laser) is relatively simple and does not require secondary epitaxy. However, due to the large waveguide loss, the output power is generally not high, and it is difficult to meet practical requirements.

[0004] In the actual communication process, in order to better realize the coupling between the laser and the optical fiber, it is generally required that the far-field divergence angle of the laser output beam be small, but because the active region of the quantum cascade laser is very thin, only 2 to 3 μm, And the lasing wavelength is in the mid-infrared band, so the far-field divergence angle is larger than that of ordinary semiconductor lasers, about 50°, which greatly affects the application of quantum cascade lasers in communications

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