G.-H. Duan

Low-Threshold Heterogeneously Integrated InP/SOI Lasers With a Double Adiabatic Taper Coupler

We report on a heterogeneously integrated InP/silicon-on-insulator (SOI) laser source realized through divinylsiloxane-bis-benzocyclobutene (DVS-BCB) wafer bonding. The hybrid lasers present several new features. The III-V waveguide has a width of only 1.7 μm, reducing the power consumption of the device. The silicon waveguide thickness is 400 nm, compatible with high-performance modulator designs and allowing efficient coupling to a standard 220-nm high index contrast silicon waveguide layer. In order to make the mode coupling efficient, both the III-V waveguide and silicon waveguide are tapered, with a tip width for the III-V waveguide of around 800 nm. These new features lead to good laser performance: a lasing threshold as low as 30 mA and an output power of more than 4 mW at room temperature in continuous-wave operation regime. Continuous wave lasing up to 70°C is obtained.

Pulse generation at 346 GHz using a passively mode locked quantum-dash-based laser at 1.55 μm

We report on subpicosecond pulse generation at 346 GHz repetition rate based on InAs/InP quantum dash passively mode locked lasers emitting at 1.55 μm. This is achieved owing to the high optical modal gain of the multilayer InAs/InP quantum dash active region.

Fabrication of low loss two-dimensional InP photonic crystals by inductively coupled plasma etching

Reference LOEQ-ARTICLE-2004-023View record in Web of Science Record created on 2007-08-31, modified on 2017-05-12

Heterogeneously integrated III-V/silicon distributed feedback lasers

Heterogeneously integrated III-V-on-silicon second-order distributed feedback lasers utilizing an ultra-thin DVS-BCB die-to-wafer bonding process are reported. A novel DFB laser design exploiting high confinement in the active waveguide is demonstrated. A 14 mW single-facet output power coupled to a silicon waveguide, 50 dB side-mode suppression ratio and continuous wave operation up to 60°C around 1550 nm is obtained.

High Gain (30 dB) and High Saturation Power (11 dBm) RSOA Devices as Colorless ONU Sources in Long-Reach Hybrid WDM/TDM-PON Architecture

We propose a hybrid wavelength-division-multi-plexing/time-division-multiplexing architecture using reflective semiconductor optical amplifiers (RSOAs) for next-generation access solutions. We demonstrate that the use of a high gain and high output power RSOA as remote modulator enables a 36-dB optical budget for colorless operation at 2.5 Gb/s over 45-km single-mode fiber. This RSOA-based configuration provides a reasonable cost per user for this hybrid system and can be easily upgraded.

Hole depth- and shape-induced radiation losses in two-dimensional photonic crystals

A phenomenological model is adopted to study three-dimensional radiation losses in two-dimensional (2D) photonic crystals (PhC) deeply etched in a step-index waveguide. In the case of low vertical refractive index contrast, losses are modeled in a 2D approach and out-of-plane scattering is translated into an effective imaginary index in the air holes. The case of truncated-cone holes is analytically solved. Depth and shape contributions to losses are extracted showing that the verticality of the hole sidewalls is a fundamental parameter. In order to validate the model, the case of a 2D triangular lattice etched through an InP/GaInAsP slab waveguide is studied both theoretically and experimentally.

Short pulse generation using a passively mode locked single InGaAsP/InP quantum well laser

We report on subpicosecond pulse generation using passively mode locked lasers (MLL) based on a low optical confinement single InGaAsP/InP quantum well active layer grown in one epitaxial step. Systematic investigation of the performances of two-section MLLs emitting at 1.54 microm evidenced pulse width of 860 fs at 21.31 GHz repetition rate, peak power of approximately 500 mW and a time-bandwith product of 0.57. A 30 kHz linewidth of the photodetected radio-frequency electrical spectrum is further demonstrated at 21 GHz which is, to our knowledge, the lowest value ever reported for a quantum well device.

Compact wavelength monitoring by lateral outcoupling in wedged photonic crystal multimode waveguides

A device concept for laterally extracting selected wavelengths from an optical signal traveling along a waveguide, for operation in metropolitan area networks, is presented. The signal on the fundamental mode of a multimode photonic crystal waveguide is coupled to a higher-order mode, at a center frequency that spatially depends on the slowly varying guide parameters. The device is compact, intrinsically fault tolerant, and can split any desired fraction of the signal for monitoring purpose. Characterizations by the internal light source technique validate the optical concept whereas an integrated device with four photodiodes qualifies its potential with respect to real-world applications.

Phase Noise Reduction of a Quantum Dash Mode-Locked Laser in a Millimeter-Wave Coupled Opto-Electronic Oscillator

Quantum dash active region Fabry-Perot lasers emitting at 1570 nm without an absorbing section have been evaluated as an optical source for microwave signal generation. These devices self-pulsate at 39.9 GHz with a mode-beating spectral linewidth as narrow as 10 kHz. Integration of these devices into an Opto-Electronic Oscillator has been performed, demonstrating a phase noise reduction of more than 15 dB in the low-frequency range. Moreover, the measured phase noise spectrum is well explained by a rate equation model taking into account the feedback loop.

Widely wavelength tunable hybrid III–V/silicon laser with 45 nm tuning range fabricated using a wafer bonding technique

A hybrid III-V on silicon laser, integrating two intra-cavity ring resonators, is fabricated by using a wafer bonding technique. It achieves a thermal tuning range of 45 nm, with side mode suppression ratio higher than 40 dB.