Demonstration of enhanced side-mode suppression in metal-filled photonic crystal vertical cavity lasers

Abstract

Previously reported simulations have suggested that depositing thin layers of metal over the surface of a single-mode, etched air hole photonic crystal (PhC) vertical-cavity surface-emitting laser (VCSEL) could potentially improve the laser's side-mode suppression ratio by introducing additional losses to the higher-order modes. This work demonstrates the concept by presenting the results of a 30 nm thin film of Cr deposited on the surface of an implant-confined PhC VCSEL. Both experimental measurements and simulation results are in agreement showing that the single-mode operation is improved at the same injection current ratio relative to threshold.

Honeycomb photonic crystal vertical-cavity surface-emitting lasers: coupled cavities enhancing the single-mode range

“…However, the simulation of a HPhC-VCSEL with etching depth of 20 mirror pairs has proved an average 1-2 dB improvement in side-mode suppression ratio. This falls in the same range as the calculated 1.8 dB enhancement in a different solution utilizing metal-filled PhC holes [8].…”

“…Photonic crystal (PhC) holes etched deeply into the top distributed Bragg reflector (DBR) of a VCSEL can also be used to produce single-mode lasers [7,8]. Airholes arranged in a regular pattern introduce an effective index step between the etched region and a central defect area that consists of a single or multiple missing holes [9][10][11].…”

“…Single-mode power from PhC-VCSELs reached 3.1 mW at 17 mA bias current in past years [17,18], and 1.7 mW together with submilliampere threshold current [11]. Chromium deposited to the bottom of the holes has also been presented to improve the side-mode suppression very recently [8], although it has also raised the threshold current.…”