Chin-Han Lin

Efficient sources for chip-to-chip to box-to-box communication within data centers

Vertical-cavity lasers with strained active regions show increased modulation rates and reliability at lower power dissipation. However, their longer wavelength (980–1100 nm) than the standard 850 nm has inhibited their widespread adoption. Given the huge emerging markets for high-speed, high-efficiency data links, should this inhibition be overcome?

Control of Polarization Phase Offset in Low Threshold Polarization Switching VCSELs

Both polarization switching and control over the angle between polarization states is demonstrated. A novel dual intracavity contacted vertical-cavity surface-emitting laser utilizing asymmetric current injection is tested. Large extinction ratios 21 dB and a record-low threshold current of 0.19 mA is achieved for such devices. Control over the phase offset between two polarization states is accomplished by rotating current injection direction relative to the axis. The phase offset between two polarization states is shown to follow a trigonometric function with maximum offsets along the and directions and minimum offsets along the and directions.

Integrated 30GHz passive ring mode-locked laser with gain flattening filter

We demonstrated a 30GHz integrated InGaAsP/InP ring mode-locked laser with a gain flattening filter that doubles the locking bandwidth and decreases the pulse width from 840fs to 620fs.

First demonstration of modulation via field-induced charge-separation in VCSELS

Novel three-terminal field-induced charge-separation lasers (FICSLs) in VCSEL form were designed and fabricated. The new gain modulation mechanism of hole-electron separation was demonstrated for the first time by applying a variable gate voltage with a constant injection current to the active region.

Ultra-compact, high-yield intra-cavity contacts for GaAs/AlGaAs-based vertical-cavity surface-emitting lasers

A novel method of fabricating compact intra-cavity contacts with high yield for GaAs/AlGaAs-based vertical-cavity surface-emitting lasers is presented. By carefully tailoring the composition of high-aluminum content layer, a highly selective Al2O3 etch-stop layer can be formed simultaneously with the oxide aperture during wet thermal oxidation. With this technique, contact metals can be uniformly deposited on deeply embedded contact layers over large substrate areas. Utilizing this embedded etch-stop design, dual intra-cavity contacted three-terminal vertical-cavity surface-emitting lasers were fabricated, demonstrating submilliampere threshold currents, over 54% differential quantum efficiencies and over 9 mW output powers.

High-speed potential of field-induced charge-separation lasers for short-link applications

Novel three-terminal FICSLs in VCSEL form were designed and fabricated for direct gain modulation, which by analysis introduces an additional zero to the modulation transfer function and promises modulation bandwidth enhancement.

Electro-thermal single-mode tuning in field-induced charge-separation lasers

We demonstrate the wavelength tunability via electro-thermal effect of field-induced charge-separation lasers (FICSLs). A large 6.6 nm tuning range is achieved with only 4.6 mA of tuning current. This high tuning efficiency persists up to about 40 kHz.

Lateral carrier injection with n-type modulation-doped quantum wells in VCSELs

We have demonstrated a novel Field-Induced Charge-Separation Laser (FICSL) in a Vertical-Cavity Surface-Emitting Laser (VCSEL) embodiment. In addition to the initial optical modulation results that have been presented [1], we here for the first time present details on the novel lateral charge injection structure as well as the advanced bandgap engineering involved in the gate structure. These features together permit high-speed light modulation with a nearly constant injection current. The result is an entirely new concept for high-speed directly-modulated semiconductor lasers.