VCSEL

VCSEL. See Vertical cavity surface-emitting lasers. 

Fig. 10. Cross-sectional drawing of a vertical cavity surface emitting laser (VCSEL). Proton implantation is used to channel the current through a small active region. Light is emitted in the direction perpendicular to the plane of the wafer. This makes preparation of two-dimensional arrays quite easy.

Fig. 12. Schematic of surface-emitting laser diodes where U represents the active region (a) planar cavity surface-emitting laser diode (PCSEL) with 45° etched reflectors and (b) vertical cavity surface-emitting laser diode (VCSEL) with semiconductor-based multilayer mirror stacks grown into the stmcture.

See also Planar cavity surface-emitting laser (PCSEL) diodes Vertical cavity surface-emitting laser (VCSEL) diodes compound semiconductor-based, 22 179 Laser Doppler velocimetry (LDV), 11 784 Laser Doppler velocimeters, 11 675 Laser-drilled surgical needles, 24 206 Laser dye energy levels, 14 702-703 Laser fabrication techniques, titanium, 24 857... 

P. Bienstman and R. Baets, Optical modelling of photonic crystals and VCSELs using eigenmode expansion and perfectly matched layers, Opt. Quantum Electron. 33, 327-341 (2001). 

SMV spectral match value VCSEL vertical cavity surface-emitting... 

B1 Optical Gain and Threshold Current Density of GaN-Based VCSELs... 

The device diameter defined by the radius of the active region is also a very important parameter for low threshold devices. We have to decrease the diameter to realise a low threshold VCSEL. In... 

FIGURE 4(a), the relation between device diameter and threshold current is shown. In this estimation, the structure shown in FIGURE 4(b) has been assumed. The transverse optical confinement factor for a cylindrical waveguide with GaN core and AIN cladding was taken into account in this estimation [8,17]. If we can fabricate the device with a diameter less than 10 pm, a GaN-based VCSEL with sub-milliampere threshold currents can be expected. 

There may be some unknown substantial problems in realising GaN-based VCSELs as well as some technique issues which should be explored. Further engineering studies are required to realise high performance GaN VCSELs. 

In a somewhat similar fashion, Ishii et alP- have demonstrated inkjet fabrication of polymeric microlenses for optical chip packaging. UV curable epoxy resin is deposited onto optical devices by inkjet printing. When the droplets hit the surface, they form into partial spheres due to their surface tension, and are UV-cured to form the microlens with diameters from 20 to 40 tm with /-numbers of 1.0 to 11.0. Their uniformity in a microlens array was measured to be within 1% in diameter and 3 tm in pitch (total count of 36 lenses). They have also demonstrated hybrid integration of inkjetted microlenses with a wire-bonded vertical-cavity-surface-emitting laser (VCSEL) with coupling efficiencies of 4 dB higher than without the microlens. 

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