686
23 Electricity-to-Light Conversion
Fig. 23.69 Simulation of the longitudinal distribution of the optical field in a VCSEL structure. The active medium are
five quantum wells in the center. Reproduced from [2024] by permission from the MRS Bulletin
(a)
(b)
Fig. 23.70 a Schematic cross section of VCSEL with oxide aperture, b TEM image of cross section. Reproduced from
[2024] by permission from the MRS Bulletin
and the upper mirror [2025]. Applying a voltage to the lever arm with the top mirror, the width of
the air gap can be varied. This variation leads to a shift of the cavity mode and therefore of the laser
emission wavelength (Fig. 23.71). A VCSEL with air gap and particularly a high contrast Bragg mirror
is achieved with InP/air as shown in Fig. 23.72.
23.4.15 Optically Pumped Semiconductor Lasers
An easy way to pump semiconductor lasers is optical pumping. This technique is similar to diodepumped solid-state lasers (DPSS). A (semiconductor) pump diode illuminates a suitable semiconductor
structure (Fig. 23.73). The resonator is built between the bottom Bragg mirror of the semiconductor
and the output coupler. The semiconductor structure contains suitable absorption layers (barriers)
that absorb the pump light and quantum wells that emit laser radiation. This radiation is intracavity
frequency doubled. In order to reach, e.g., a 488-nm output laser beam, a standard 808-nm pump
diode is employed. The InGaAs/GaAs quantum wells are designed to emit at 976 nm. Other design
wavelengths of the quantum wells allow for other output wavelengths. This technology allows compact
lasers with little heat dissipation [2028]. The optically pumped semiconductor laser (OPSL) is also
known as a semiconductor disc laser.
23 Electricity-to-Light Conversion
Fig. 23.69 Simulation of the longitudinal distribution of the optical field in a VCSEL structure. The active medium are
five quantum wells in the center. Reproduced from [2024] by permission from the MRS Bulletin
(a)
(b)
Fig. 23.70 a Schematic cross section of VCSEL with oxide aperture, b TEM image of cross section. Reproduced from
[2024] by permission from the MRS Bulletin
and the upper mirror [2025]. Applying a voltage to the lever arm with the top mirror, the width of
the air gap can be varied. This variation leads to a shift of the cavity mode and therefore of the laser
emission wavelength (Fig. 23.71). A VCSEL with air gap and particularly a high contrast Bragg mirror
is achieved with InP/air as shown in Fig. 23.72.
23.4.15 Optically Pumped Semiconductor Lasers
An easy way to pump semiconductor lasers is optical pumping. This technique is similar to diodepumped solid-state lasers (DPSS). A (semiconductor) pump diode illuminates a suitable semiconductor
structure (Fig. 23.73). The resonator is built between the bottom Bragg mirror of the semiconductor
and the output coupler. The semiconductor structure contains suitable absorption layers (barriers)
that absorb the pump light and quantum wells that emit laser radiation. This radiation is intracavity
frequency doubled. In order to reach, e.g., a 488-nm output laser beam, a standard 808-nm pump
diode is employed. The InGaAs/GaAs quantum wells are designed to emit at 976 nm. Other design
wavelengths of the quantum wells allow for other output wavelengths. This technology allows compact
lasers with little heat dissipation [2028]. The optically pumped semiconductor laser (OPSL) is also
known as a semiconductor disc laser.