Vertical cavity semiconductor lasers
First Claim
1. In a vertical cavity semiconductor laser an active region which generates optical radiation and a mirror stack which reflects the radiation, the stack containing a plurality of spatial periods each of which consists of essentially a quarter-wavelength layer of first semiconductor material and a quarter-wavelength layer of second semiconductor material which is different from the first,the layer of second material having energy a bandgap that is equal to or less than the energy per photon of the radiation, andthe layer of second material containing a concentration of impurities sufficient to render the second material degenerate and significantly less absorptive of the radiation.
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Abstract
In a vertical cavity laser, such as an InP based vertical laser, the energy bandgap in the active region can be made equal to or larger than the bandgap in a semiconductor mirror stack by virtue of degenerate doping in the stack sufficient to suppress electronic band-to-band optical absorption. For example, the active region of an InP based laser can be lattice-matched GaInAs, GaInAsP, or a multiple quantum well structure composed of layers of InP and GaInAs--with the mirror stack composed of alternating layers of InP and degenerately doped n-type lattice-matched GaInAs or GaInAsP.
47 Citations
18 Claims
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1. In a vertical cavity semiconductor laser an active region which generates optical radiation and a mirror stack which reflects the radiation, the stack containing a plurality of spatial periods each of which consists of essentially a quarter-wavelength layer of first semiconductor material and a quarter-wavelength layer of second semiconductor material which is different from the first,
the layer of second material having energy a bandgap that is equal to or less than the energy per photon of the radiation, and the layer of second material containing a concentration of impurities sufficient to render the second material degenerate and significantly less absorptive of the radiation.
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4. In a vertical cavity laser:
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(a) an InP semiconductor body having essentially planar top and bottom major surfaces; (b) a mirror stack located on the top surface of the body, the stack being composed of a plurality of alternating layers of n-type InP and lattice-matched n-type GaInAs or GaInAsP; (c) an active region composed essentially of lattice-matched GaInAs or lattice-matched GaInAsP, or quantum wells of InP and lattice-matched GaInAs or lattice-matched GaInAsP, the active region separated from the top surface of the mirror stack by an n-type optical cladding layer of InP, the doping level of the active region being less than that of the cladding layer, and the doping level of the cladding layer being less than that of the lattice-matched GaInAs or GaInAsP in the mirror stack, the layers of GaInAs or GaInAsP in the mirror stack having doping levels that are sufficiently high to render them degenerately doped. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification