Distributed feedback broad area lasers with multiple epitaxially stacked active regions and tunnel junctions.

Distributed feedback (DFB) broad area (BA) lasers with multiple epitaxially stacked active regions and tunnel junctions designed for emission around 900 nm are investigated. DFB BA lasers with a cavity length of 1 mm and different stripe widths are compared in terms of their electro-optical performance and beam quality. The laser with a 200 µm stripe width achieved a high optical pulse power of 100 W in 10 ns long pulses at an injection current of 63 A, resulting in a brightness of 81 MW/cm2sr. The optical spectrum of both lasers is centered at around 886 nm, exhibiting a narrow spectral bandwidth of 0.2 nm (64 pm/K).

Hybrid integrated mode-locked laser using a GaAs-based 1064 nm gain chip and a SiN external cavity.

External cavity mode-locked lasers could be used as comb sources for high volume application such as LIDAR and dual comb spectroscopy. Currently demonstrated chip scale integrated mode-locked lasers all operate in the C-band. In this paper, a hybrid-integrated external cavity mode-locked laser working at 1064 nm is demonstrated, a wavelength beneficial for optical coherence tomography or Raman spectroscopy applications. Additionally, optical injection locking is demonstrated, showing an improvement in the optical linewidth, and an increased stability of the comb spectrum.

Spatially modulated broad-area lasers for narrow lateral far-field divergence.

A novel laser design is presented that combines a longitudinal-lateral gain-loss modulation with an additional phase tailoring achieved by etching rectangular trenches. At 100 A pulsed operation, simulations predict a far-field profile with 0.3° full width at half maximum (Θ F W H M =0.3 ∘ ) where a 0.4°-wide main lobe contains 40% of the emitted optical output power (Θ 40% =0.4 ∘ ). While far-field measurements of these structured lasers emitting 10 ns long pulses with 35 W peak power confirm a substantial enhancement of radiation within the central 1∘ angular range, the measured far-field intensity outside of the obtained central peak remains high.

Comparison of symmetric and asymmetric double quantum well extended-cavity diode lasers for broadband passive mode-locking at 780 nm.

We present a compact, mode-locked diode laser system designed to emit a frequency comb in the wavelength range around 780 nm. We compare the mode-locking performance of symmetric and asymmetric double quantum well ridge-waveguide diode laser chips in an extended-cavity diode laser configuration. By reverse biasing a short section of the diode laser chip, passive mode-locking at 3.4 GHz is achieved. Employing an asymmetric double quantum well allows for generation of a mode-locked optical spectrum spanning more than 15 nm (full width at -20 dB) while the symmetric double quantum well device only provides a bandwidth of ∼2.7 nm (full width at -20 dB). Analysis of the RF noise characteristics of the pulse repetition rate shows an RF linewidth of about 7 kHz (full width at half-maximum) and of at most 530 Hz (full width at half-maximum) for the asymmetric and symmetric double quantum well devices, respectively. Investigation of the frequency noise power spectral density at the pulse repetition rate shows a white noise floor of approximately 2100 Hz2/Hz and of at most 170 Hz2/Hz for the diode laser employing the asymmetric and symmetric double quantum well structures, respectively. The pulse width is less than 10 ps for both devices.