Publications

We report the demonstration of an InGaAlAs/InP quantum-well, high-power, low-noise packaged semiconductor external cavity laser (ECL) operating at 1550 nm. The laser comprises a double-pass, curved-channel slab-coupled optical waveguide amplifier (SCOWA) coupled to a narrow-bandwidth (2.5 GHz) fiber Bragg grating passive cavity using a lensedfiber. At a bias current of...

Uni-traveling-carrier waveguide photodiodes (PDs) with a variable optical confinement mode size transformer are demonstrated. The optical mode is large at the input for minimal front-end saturation and the mode transforms as the light propagates so that the absorption profile is optimized for both high-power and high-speed performance. Two differently designed...

In this paper we study the uniformity of up to 150 mm in diameter wafer-scale III-V epitaxial transfer to the Si-on-insulator substrate through the O2 plasma-enhanced low-temperature (300°C) direct wafer bonding. Void-free bonding is demonstrated by the scanning acoustic microscopy with sub-um resolution. The photoluminescence (PL) map shows less than...

The semiconductor slab-coupled optical waveguide (SCOW) concept is a versatile device platform that has enabled new classes of high-power, low-noise single-frequency lasers, mode-locked lasers, optical amplifiers, and photodiodes for analog optical links and photonic analog-to-digital converters.

We demonstrate the transfer of the largest (150 mm in diameter) available InP-based epitaxial structure to the silicon-on-insulator substrate through a direct wafer-bonding process. Over 95% bonding yield and a void-free bonding interface was obtained. A multiple quantum-well diode laser structure is well-preserved after bonding, as indicated by the high-resolution...

We report the first high-current photodiode based on the slab-coupled optical waveguide concept. The device has a large mode (5.8 x 7.6 um) and ultra-low optical confinement ([] ~ 0.05%), allowing a 2-mm absorption length. The maximum photocurrent obtained was 250 mA (R = 0.8-A/W) at 1.55 um.

We report the demonstration of a 1.5 um InGaAsP mode-locked slab-coupled optical waveguide laser (SCOWL) producing 10 ps pulses with energies of 58 pJ and average output powers of 250 mW at a repetition rate of 4.29 GHz. To the best of our knowledge, this is the first passively mode-locked...

Advanced analog-optical sensor, signal processing and communication systems could benefit significantly from wideband (DC to > 50 GHz) optical modulators having both low half-wave voltage (V[pi]) and low optical insertion loss. An important figure-of-merit for modulators used in analog applications is TMAX/V[pi], where TMAX is the optical transmission of the...

Phase-encoded optical sampling allows radio-frequency and microwave signals to be directly down-converted and digitized with high linearity and greater than 60-dB (10-effective-bit) signal-to-noise ratio. Wide-band electrical signals can be processed using relatively low optical sampling rates provided that the instantaneous signal bandwidth is less than the Nyquist sampling bandwidth. We...

Optically sampled analog-to-digital converters (ADCs) combine optical sampling with electronic quantization to enhance the performance of electronic ADCs. In this paper, we review the prior and current work in this field, and then describe our efforts to develop and extend the bandwidth of a linearized sampling technique referred to as...