Quanan Chen

Optimization algorithm based characterization scheme for tunable semiconductor lasers

An optimization algorithm based characterization scheme for tunable semiconductor lasers is proposed and demonstrated. Using modern optimization algorithms, we can get stable operating condition for tunable lasers at any frequency directly and efficiently.

Demonstration of Multi-Channel Interference Widely Tunable Semiconductor Laser

In this letter, we report the first experimental demonstration of the multi-channel interference (MCI) widely tunable semiconductor laser. Mode selection of the MCI laser is achieved by the constructive interference of eight arms with unequal length difference. Compared with conventional widely tunable semiconductor lasers based on distributed Bragg reflectors, fabrication of the MCI laser is simpler with large fabrication tolerances. A quasi-continuous tuning range of about 52.3 nm (1538.96-1591.26 nm) has been demonstrated at a temperature of 23 °C with side-mode suppression-ratios greater than 44 dB across the whole tuning range (typically greater than 48 dB).

Theory and simulation of multi-channel interference (MCI) widely tunable lasers

A novel design of an InP-based monolithic widely tunable laser, multi-channel interference (MCI) laser, is proposed and presented for the first time. The device is comprised of a gain section, a common phase section and a multi-channel interference section. The multi-channel interference section contains a 1x8 splitter based on cascaded 1 × 2 multi-mode interferometers (MMIs) and eight arms with unequal length difference. The rear part of each arm is integrated with a one-port multi-mode interference reflector (MIR). Mode selection of the MCI laser is realized by the constructive interference of the lights reflected back by the eight arms. Through optimizing the arm length difference, a tuning range of more than 40 nm covering the whole C band, a threshold current around 11.5 mA and an side-mode-suppression-ratio (SMSR) up to 48 dB have been predicted for this widely tunable laser. Detailed design principle and numerical simulation results are presented.

Grating-Assisted Microcylinder Surface-Emitting Laser

A novel design of grating-assisted microcylinder surface-emitting laser (GAMSEL) is presented. GAMSEL has two gratings: top grating and side grating. Both gratings have the number of periods close to the azimuthal mode number of the whispering gallery mode (WGM) supported by the microcylinder cavity, therefore, they behave like second-order gratings of a straight waveguide. The top grating scatters the WGM vertically so as to form the surface emission while the side grating selects the mode having the proper emission pattern to lase. Through the cooperation of the two gratings, GAMSEL becomes a single-mode surface-emitting laser. Due to its small volume, GAMSEL is predicted through simulation to have a threshold current about 1 mA and a direct modulation bandwidth higher than 40 GHz. Besides, relying on the lateral microcylinder cavity, GAMSEL does not require highly reflective mirrors as vertical-cavity surface-emitting lasers do, which makes this design easily apply to different wavelengths such as the near infrared 1310- and 1550-nm wavelength bands.

High SMSR monolithic widely tunable semiconductor lasers based on multi-channel interference

Monolithic widely tunable semiconductor lasers based on multi-channel interference (MCI) have been demonstrated with tuning range more than 53.6 nm and SMSR up to 52 dB being achieved.

A Novel Surface-Emitting Laser based on Microcylinder Cavity Etched with Second-Order Gratings

A novel surface-emitting laser structure based on a microcylinder cavity etched with second-order gratings, is presented. Extensive numerical simulations show that ∼1mA threshold current and >40GHz direct modulation bandwidth can be realized with it.