Denselight Semiconductor Pte Ltd

Teik Kooi Ong

Yee Loy Lam

Yuen Chuen Chan

Lay Cheng Choo

Peh Wei Tan

Hwi Siong Lim

The layer structure of a DC-PBH laser diode consists of an n-InP substrate ( ), an n-InP buffer layer ( ), an undoped-InGaAsP active layer ( ), a p-Inp cladding layer ( ), a p-InP current blocking layer ( ), an n-InP current blocking layer ( ), a p-InP cladding layer ( ), and a p-InGaAsP contact layer ( ). An additional layer of Fe-doped InP layer ( ) creates an acceptor level (Fe /Fe ) near mid-band gap. The iron impurities are deep level traps, and will make the capacitance C less dependent of the impurity concentration of layer ( ) which is normally doped with a concentration larger than 1&times;10 cm to lower the leakage current from p-InP blocking layer ( ) to p-InP blocking layer ( ) that does not contribute to light emission. The capacitance C and hence the overall capacitance C will be reduced with this Fe doped InP layer ( ) and consequently the displacement current through the current blocking structure during high speed operation will be lowered. In addition, as this Fe-doped InP layer is also a thermally stable semi-insulating material, a high resistivity layer is thus formed between the n-InP blocking layer ( ) and P-InP blocking layer ( ). Thus, this Fe doped InP layer ( ) will also effectively reduce the leakage current flowing through the p-n-p-n current blocking channel as mentioned above.

Current blocking structure to improve semiconductor laser performance

There is provided a semiconductor laser comprising a gain section and an adjacent Bragg section, wherein output laser light is emitted via a facet at an interface between air and the gain section, the Bragg section comprising a distributed reflecting structure having a length substantially greater than required to ensure single longitudinal mode operation of the laser in which the side-mode suppression ratio (SMSR) is 35 dB or more, thereby in use substantially suppressing optical feedback from a facet at an interface between the Bragg section and air, and wherein an interface between the Bragg section and the gain section is quantum well intermixed, thereby rendering the interface substantially anti-reflecting at the wavelength of the laser.

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Singapore, Singapore

Teik Kooi Ong