Denselight Semiconductor Pte Ltd

Denselight Semiconductors Pte Ltd

Ntu Ventures Pte. Ltd.

Nanyang Technological University

Yuen Chuen Chan

Yee Loy Lam

Siu Chung Tam

Hwi Siong Lim

Teik Kooi Ong

Peh Wei Tan

Bee Khuan Law

Yan Zhou

Long Cheng Koh

Lay Cheng Choo

Hon Yuen Aaron Sim

Ter Hoe Loh

Chai Leng Terence Wee

Andy Piper

Xiangjun Mao

Pei Wei Tan

Nakamura Hiroshi

Boon Siew Ooi

A photonic integrated circuit (PIC) includes various mode field adapters (MFAs), a waveguide, and various contact pads. All the MFAs are on a same facet of the PIC. One MFA of the PIC outputs a first optical signal that is an amplified version of a second optical signal. The waveguide is divided into two waveguide arms and a bend portion to join the two waveguide arms. The waveguide extends between the MFAs such that the second optical signal propagates through the waveguide. Further, each waveguide arm is formed between the contact pads. The second optical signal propagating through the waveguide is amplified based on a current that is injected in the PIC by way of the contact pads.

Photonic integrated circuit for amplifying optical signals

The invention provides a method of growing semiconductor epitaxial layers on a substrate comprising the steps of

Liquid phase epitaxy

A device for optical space switching in optical networks. The optical device comprises a broad area optical waveguide section having a number of electrodes extending over at least a portion of the length of the broad area optical waveguide section. The application of an electrical signal to an electrode causes a local change in effective refractive index of the broad area optical waveguide section, thereby causing light preferentially to propagate along a predetermined path in dependence on the configuration of the electrode. In particular the broad area waveguide device is implemented in indium phosphide (InP). Also described is a method for waveguiding in the optical device.

Optical space switch

The present invention relates to a semiconductor optical tap comprising: a multimode interferometer (MMI) (); an input waveguide () coupled to the MMI; a first output waveguide () coupled to the MMI; and a second output waveguide () coupled to the MMI. The first and second output waveguides () overlap (d) such that unequal portions of light are coupled from the MMI into the first and second output waveguides (). The input waveguide () and the first and second output waveguides () may have a rib structure. They may also be adiabatically tapered waveguides. The first and second output waveguides () may have different starting widths.

Optical tap

The present invention relates to a semiconductor photodetector. The photodetector is a waveguide photodetector, which comprises: a waveguide ( ) having a III-V ridge structure including an active layer ( ); a semiconductor layer ( ) deposited on top of the ridge structure; and, metal detector electrodes (not shown) on the surface of the higher refractive index semiconductor layer ( ). The semiconductor layer ( ) has a higher refractive index than the waveguide structure ( ). The ridge structure is configured to widen along the length of the waveguide ( ) such that light passing through the active layer ( ) of the waveguide couples more efficiently up into the higher refractive index semiconductor layer ( ).

High speed waveguide photodetector

We propose a technique for fabricating stacked photonic lightwave circuits (PLCs), with both high and low refractive index steps, comprising the use of etched PECVD dielectric layers for the light guiding structures and which are surrounded and separated by an interlayer PLC cladding (IPC) comprising a non-conformal layer of sol-gel, whose composition, refractive index and thickness can be tailored to the requirements of the device.

Fabrication of stacked photonic lightwave circuits

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.

Two-section distributed Bragg reflector laser

A wavelength locked tunable laser source comprising a tunable laser source, an optical reference source characterized by a frequency spectrum with two combs of discrete components of different spacing, an optical mixing device and feedback control circuitry. An optical output of the laser source is heterodyned with an output of the optical reference source at the optical mixing device to produce an electrical signal in dependence on a difference beat frequency of the two optical outputs, the feedback control circuitry being operative to process the electrical signal to provide a feedback signal which is used to tune the wavelength of the laser source so as to minimize the beat frequency and thereby substantially lock the wavelength of the laser source to a wavelength in the spectrum of the optical reference source. The use of an optical reference source with a spectrum comprising two frequency combs provides a mechanism for determining the absolute frequency to which the laser has been locked.

Active wavelength locking

A pumping module for use in a solid state laser comprises an annular array of laser diode segments ( ) forming a passage ( ), each segment ( ) comprising an extended body supporting a laser diode array ( ) that extends along the longitudinal axis of the segment ( ) for directing light into the passage ( ) from an inner face ( ) of the annular array, wherein adjacent side faces of any two segments ( ) in the annular array are in sealing engagement. The inner faces ( ) of the array of segments ( ) form a continuous surface so that coolant can flow between a laser rod and the segments ( ) to reduce localized heating.

Pumping source

The present invention provides a novel technique based on gray scale mask patterning ( ), which requires only a single lithography and etching step ( ) to produce different thickness of SiO implantation mask ( ) in selected regions followed by a one step IID ( ) to achieve selective area intermixing. This novel, low cost, and simple technique can be applied for the fabrication of PICs in general, and WDM sources in particular. By applying a gray scale mask technique in IID in accordance with the present invention, the bandgap energy of a QW material can be tuned to different degrees across a wafer ( ). This enables not only the integration of monolithic multiple-wavelength lasers but further extends to integrate with modulators and couplers on a single chip. This technique can also be applied to ease the fabrication and design process of superluminescent diodes (SLDs) by expanding the gain spectrum to a maximum after epitaxial growth.

Growing community of inventors

Singapore, Singapore

Yuen Chuen Chan