Justin K. Alexander

Monolithically integrated low linewidth comb source using gain switched slotted Fabry-Perot lasers

A monolithically integrated low linewidth optical comb is demonstrated by gain switching of a three-section laser device. The device consists of a slave and master section separated by a shared slotted mirror section. Wavelength tunability has been demonstrated by varying the electrical bias of each section. The number of comb lines is shown to almost double with the addition of optical injection from the master section into the slave. The unmodulated device has a full width half max linewidth of ∼ 500 kHz, while the comb line set were measured to be ∼ 600 kHz, with little degradation as a result of gain switching. The FSR (free spectral range) of the demonstrated comb is 4 GHz, which is tunable within the bandwidth of the device, with a central wavelength of 1580.3 nm.

Regrowth-Free Single Mode Laser Based on Dual Port Multimode Interference Reflector

This letter demonstrates an InP-based photonic integrated circuit that utilizes an etched facet and a dual port multimode interference reflector to create a lasing cavity. The laser was fabricated using UV lithography and did not require any epitaxial regrowth. A single deep etched slot produced single mode behavior due to the coupled cavity effect. By varying the bias of the two sub cavities, mode selectivity with a side mode suppression ratio of 30 dB is demonstrated.

On-Chip Investigation of Phase Noise in Monolithically Integrated Gain-Switched Lasers

Phase noise in gain-switched lasers is investigated theoretically using the semiconductor laser rate equations and compared with the experimental results from monolithically integrated devices. The phase noise of a gain-switched laser is modelled both with and without injection-locking using the rate equations for a single-mode laser. Phase noise is found to increase with gain-switching, and decrease when injection-locked to a master laser. This trend is then observed experimentally on-chip with monolithically integrated devices without the use of an isolator.

Widely tunable facetless regrowth-free semiconductor laser

A design for a laser is presented here, based on gold-coated on-chip etched facets and multimode interference (MMI) couplers [1]. The laser (shown in Fig. 1) was fabricated from commercially obtained regrowth-free 1550nm laser material and using exclusively standard UV lithography. The fabrication process is a two etch-depth process compatible with most standardised shared foundry processes [2]. The single-mode operation was achieved by the crossing of a central waveguide with the loop. The index perturbation caused by the crossing results in a reflection, making the device a multi-cavity laser and enabling single mode operation. Gold-coated etched facets are used as an on-chip reflective solution to remove the need for any cleaved facet from the design.

Integratable optical comb source for coherent communications systems

A coherent optical comb source is monolithically integrated. Optical combs were generated at 4 GHz and 5 GHz, with the combs produced independent of cleaved facets.

Corrections to “On-Chip Investigation of Phase Noise in Monolithically Integrated Gain-Switched Lasers” [May 1, 2017 731-734]

In the above letter equations (2) and (6) are incorrect due to an additional

Deeply Etched Inner-Cavity Pit Reflector

S

A facetless regrowth-free single mode laser based on MMI couplers

present within the bracketed term.