Improved performance of tunable single-mode laser array based on high-order slotted surface grating

Abstract

We present an improved design of a wavelength-tunable single-mode laser array based on a high order surface grating with non-uniformly spaced slots. The laser array consists of 12 slotted single-mode lasers. The fabricated device exhibits a quasi-continuous tuning range of more than 36 nm over the temperature range from 10°C - 45°C covering the full C-band. All lasers in the array have stable single-mode operation with side mode suppression ratio of 50 dB due to the modified slot design. A spectral linewidth of less than 500 kHz was obtained for all channels in the array.

Athermal operation of multi-section slotted tunable lasers

“…These lasers have found to exhibit strong performance under continuous wave (CW) operation. In previous work [3], an array of 12 slotted lasers demonstrated full C-band coverage and a threshold current of 25-35 mA at 20 • C, with a side-mode suppression-ratio (SMSR) > 40 dB and a linewidth below 500 kHz.…”

“…Although tunable DFB and DBR lasers demonstrate good optical power and wavelength stability, the high-resolution processing and complex regrowth steps involved in their fabrication can result in low yield and high manufacturing costs [3]. This high cost may be a barrier to the implementation of scalable fiber-to-the-x (FTTx) solutions, with architecture such as passive optical networks (PONs) requiring low-cost tunable lasers on the optical network unit (ONU) side [4].…”

“…A potential solution to this cost issue is to simplify the fabrication process even further by etching high order grating features on the surface of the waveguide, thereby avoiding the aforementioned high-resolution processing and regrowth steps. Such slotted lasers could be fabricated at low costs and high yield, and have been found to exhibit low threshold currents, narrow linewidths and high slope efficiencies [3,7,8].…”

Tuning behaviour of slotted vernier widely tunable lasers

“…In order to verify the accuracy of the numerical model it is first compared to experimental measurements of a simpler two section single-mode slotted laser, the details of which can be found in [7]. First, the model is compared to wavelength measurements of a tuning curve as shown in Fig.…”

“…The gratings are high order and are formed through etching slots in the ridge of the laser waveguide. We have developed single mode lasers integrated with SOAs and electro absorption modulators (EAM) [5,6], as well as laser arrays covering the C-band [7]. Using this slotted grating structure a vernier laser based on slots, analogous to the SG-DBR laser, has also been demonstrated achieving > 50 nm tuning range with SMSR > 30 dB for the majority of this range [8].…”