Corning Lasertron, Incorporated

Hanh Lu

Richard T Sahara

Randal A Salvatore

Angela Hohl-AbiChedid

Yi Qian

An integrated semiconductor device comprising a laser on a substrate, the laser having an active layer and a current-induced grating, such as a current-injection complex-coupled grating, within a laser cavity producing a single-mode output light signal at high data rates (&#x3e;622 Mb/sec) in isolator-free operation. The grating has a coupling strength product &#x3ba;L greater than 3, where &#x3ba; is the coupling coefficient and L is the length of the laser cavity. In certain embodiments, the laser is a distributed feedback (DFB) laser that emits light at a wavelength of about 1.5 &#x3bc;m. The strong current-induced grating prevents mode hopping between multiple degenerate Bragg modes. The laser is also characterized by excellent immunity from optical feedback, and can be operated without an isolator at high data rates.

Distributed feedback laser for isolator-free operation

An integrated semiconductor device comprising a wavelength-tunable laser, such as a distributed Bragg reflector (DBR) laser, where the laser has a gain section that includes an active layer, and a grating section that includes an active layer and a current-induced grating. A first electrical contact is provided over the gain section to supply current to the gain section and control the output power of the light, and a second electrical contact is provided over the grating section to supply current to the grating section and control the wavelength of the emitted light. The current-induced grating of the present device causes gain in the active layer of the laser to be modulated spatially in the direction of light propagation, thus resulting in only one of the degenerate Bragg modes to oscillate. As the degeneracy of the Bragg modes is broken by current-injection, and not facet reflection, substantially continuous wavelength tuning is possible without the deleterious phenomenon of &ldquo;mode hopping.&rdquo; The present design does not utilize a phase section, and thus eliminates the complex three-way interaction between the gain section, grating section, and a phase section. Alternative grating designs include gain-coupled gratings, complex-coupled gratings, and fractional wave shifted gratings, with relatively strong coupling products (&kgr;L>1.5), which do not rely on facet reflections to break the degeneracy of the Bragg modes.

Tunable laser device for avoiding optical mode hops

An integrated electroabsorption modulated laser (EML) device includes a distributed feedback (DFB) laser and modulator. The DFB laser includes an active layer and a complex index grating. The modulator includes an active layer. The EML device includes a first electrical contact over the DFB laser and a second electrical contact over the modulator. The EML device includes a stop etch layer above the active layer of both the DFB laser and the modulator. An electroabsorption modulated partial grating laser (EMPGL) device includes a distributed feedback (DFB) laser, an amplifier and a modulator. An ion implantation region in the EML/EMPGL devices provides electrical isolation between the DFB laser/amplifier and the modulator.

Electroabsorption modulated laser

An electro-optical, ridge-waveguide device and method for its fabrication utilizes a polyimide ridge-protection layer, which provides good ridge protection/planarization while minimizing parasitic capacitance. A silicon oxide interlayer is used between a metal contact layer and the polyimide. This interlayer facilitates the adhesion between the metal contact layer and the underlying device since good adhesion can be obtained between the silicon oxide layer and the polyimide layer and between the metal layer and silicon oxide layer. Preferably, the polyimide is roughened to increase the surface area contact between the polyimide layer and silicon oxide layer to further increase adhesion and thus the pull-off force required to separate the metal contact layer from the device. While such roughening can be achieved through plasma etching, in a preferred embodiment, the polyimide layer is roughened by patterned etching. Specifically, a patterned photoresist is used as a etch-protection layer to form a series of wells in the polyimide layer that have a pitch between 1 and 20 microns.

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North Andover, MA, United States of America

Hanh Lu