Abstract

Electrically injected visible vertical cavity surface emitting lasers (VCSELs) with AlGaInP multiple quantum well (MQW) active regions and AlGaAs distributed Bragg reflectors (DBRs) were first demonstrated in 1993.¹ Subsequent research focused on increasing device efficiency (η) and output power (L), on reducing threshold current density (J_th), and on fresh fabrication schemes.² Room temperature (RT) continuous wave (CW) visible AlGaInP VCSELs with emission wavelengths (λ_o) of 660–680 nm, L ≥ mW, and J_th ≤ 1 mA have recently been demonstrated. This performance rivals that of infrared (IR) VCSELs—circa 1990. As with similar edge-emitting lasers, the efficiency of visible AlGaInP lasers degrades rapidly as the emission wavelength is reduced–due primarily to carrier leakage from the QWs. In spite of this difficulty, RT CW edge-emitters with λ_o~610–640 nm have been demonstrated by employing advanced epitaxial layer designs that include for example: multiquantum barriers (MQBs), strained (Al_xGa_1−x)yIn_1−yP MQWs, growth on misoriented (100) GaAs substrates, and highly-doped Al_0.5In_0.5P cladding layers.^3-5 These techniques have been applied to short wavelength visible AlGaInP VCSELs, as follows.

© 1995 IEEE