1.8-μm thulium microlasers integrated on silicon

A key challenge for silicon photonic systems is the development of compact on-chip light sources. Thulium-doped fiber and waveguide lasers have recently generated interest for their highly efficient emission around 1.8 μm, a wavelength range also of growing interest to silicon-chip based systems. Here, we report on highly compact and low-threshold thulium-doped microcavity lasers integrated with silicon-compatible silicon nitride bus waveguides. The 200-μmdiameter thulium microlasers are enabled by a novel high quality-factor (Q-factor) design, which includes two silicon nitride layers and a silicon dioxide trench filled with thulium-doped aluminum oxide. Similar, passive (undoped) microcavity structures exhibit Q-factors as high as 5.7 × 10[superscript 5] at 1550 nm. We show lasing around 1.8-1.9 μm in aluminum oxide microcavities doped with 2.5 × 10[superscript 20] cm [superscript -3] thulium concentration and under resonant pumping around 1.6 μm. At optimized microcavity-waveguide gap, we observe laser thresholds as low as 773 μW and slope efficiencies as high as 23.5%. The entire fabrication process, including back-end deposition of the gain medium, is silicon-compatible and allows for co-integration with other silicon-based photonic devices for applications such as communications and sensing.United States. Defense Advanced Research Projects Agency. Microsystems Technology Office (HR0011-15-C-0056)United States. Defense Advanced Research Projects Agency. Microsystems Technology Office (HR0011-12-2-0007)Singapore. Agency for Science, Technology and Researc

Integrated mode-locked lasers in a CMOS-compatible silicon photonic platform

CLEO: Science and Innovations 2015 San Jose, California United States 10–15 May 2015 ISBN: 978-1-55752-968-8 From the session: Silicon Photonic Systems (SM2I)The final version is available from the publisher via the DOI in this record.Integrated components necessary for a mode-locked laser are demonstrated on a platform that allows for monolithic integration with active silicon photonics and CMOS circuitry. CW lasing and Q-switched mode-locking are observed in the full structures.This work was supported under the DARPA E-PHI project, grant no. HR0011-12-2-0007

Erbium-doped laser with multi-segmented silicon nitride structure

Optical Fiber Communication Conference 2014 San Francisco, California United States 9–13 March 2014 ISBN: 978-1-55752-993-0 From the session: Novel Optical Schemes (W4E)This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.We report on DFB and DBR lasers formed from a wavelength insensitive multisegmented silicon nitride waveguide. Using a five-segment waveguide, we obtain lasing in erbium-doped DBR (-3.6 dBm) and DFB (-7.3 dBm) cavities. © OSA 2014

CMOS-compatible 75 mW erbium-doped distributed feedback laser

On-chip, high-power, erbium-doped distributed feedback lasers are demonstrated in a CMOS-compatible fabrication flow. The laser cavities consist of silicon nitride waveguide and grating features, defined by wafer-scale immersion lithography and an erbium-doped aluminum oxide layer deposited as the final step in the fabrication process. The large mode size lasers demonstrate single-mode continuous wave operation with a maximum output power of 75 mW without any thermal damage. The laser output power does not saturate at high pump intensities and is, therefore, capable of delivering even higher on-chip signals if a stronger pump is utilized. The amplitude noise of the laser is investigated and the laser is shown to be stable and free from self-pulsing when the pump power is sufficiently above threshold. Efficient, low noise, narrow band and stable on-chip lasers are essential for a variety of important applications, ranging from integrated analog photonics and microwave generation to coherent communications and light detection and ranging (LiDAR). Recently, two methods have shown the greatest promise for delivering high performance, integrated silicon-compatible lasers; namely, hybrid integration of silicon-on-oxide (SOI) waveguides with III-V semiconductor gain media [1-3], and erbium/ ytterbium-doped glasses on silico

Ultra-narrow-linewidth erbium-doped lasers on a silicon photonics platform

This is the final published version. Available from the publisher via the DOI in this record.Event: Silicon Photonics XIII; 1053712, SPIE OPTO, 2018, San Francisco, California, United StatesWe report ultra-narrow-linewidth erbium-doped aluminum oxide (Al2O3:Er3+) distributed feedback (DFB) lasers with a wavelength-insensitive silicon-compatible waveguide design. The waveguide consists of five silicon nitride (SiNx) segments buried under silicon dioxide (SiO2) with a layer Al2O3:Er3+ deposited on top. This design has a high confinement factor (> 85%) and a near perfect (> 98%) intensity overlap for an octave-spanning range across near infrared wavelengths (950–2000 nm). We compare the performance of DFB lasers in discrete quarter phase shifted (QPS) cavity and distributed phase shifted (DPS) cavity. Using QPS-DFB configuration, we obtain maximum output powers of 0.41 mW, 0.76 mW, and 0.47 mW at widely spaced wavelengths within both the C and L bands of the erbium gain spectrum (1536 nm, 1566 nm, and 1596 nm). In a DPS cavity, we achieve an order of magnitude improvement in maximum output power (5.43 mW) and a side mode suppression ratio (SMSR) of > 59.4 dB at an emission wavelength of 1565 nm. We observe an ultra-narrow linewidth of ΔνDPS = 5.3 ± 0.3 kHz for the DPS-DFB laser, as compared to ΔνQPS = 30.4 ± 1.1 kHz for the QPS-DFB laser, measured by a recirculating self-heterodyne delayed interferometer (RSHDI). Even narrower linewidth can be achieved by mechanical stabilization of the setup, increasing the pump absorption efficiency, increasing the output power, or enhancing the cavity Q.This work is supported by the Defense Advanced Research Projects Agency (DARPA) Microsystems Technology Office’s (MTO) E-PHI (HR0011-12-2-0007) project. N. Li acknowledges a fellowship from the Agency of Science, Technology and Research (A*STAR), Singapore

Femtosecond laser pumped by high-brightness coherent polarization locked diodes

We demonstrate, for the first time to our knowledge, the use of a coherent polarization locked diode as the high-brightness pump source for a femtosecond laser. Four diode emitters are coherently locked to produce more than 5 W linearly polarized, narrow linewidth, and single-lobed pump beam. This gives >10× brightness improvement over the conventional diode array. The diode beam is then used to pump a Yb:KYW laser to obtain 2 W output with 57% slope efficiency in cw laser operation. By using a saturable absorber mirror, we achieved cw mode-locking operation with a 177 fs pulse width at an average power of 0.55 W

Integrated erbium lasers in silicon photonics

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.Cataloged from PDF version of thesis.Includes bibliographical references (pages 109-114).We present results on the development of integrated erbium-doped aluminum oxide lasers on a silicon photonics platform. A key achievement in this work is a scalable laser design for high output power and ultra-narrow linewidth performance. Using a novel wavelength-insensitive design, a CMOS compatible waveguide structure is proposed to achieve high confinement factor and intensity overlap for both the pump (980 nm) and signal (1550 nm) wavelengths. Laser operation in the C- and L- bands of the erbium gain spectrum is obtained with both a distributed Bragg reflector and a distributed feedback structure. We demonstrate power scaling with output power greater than 75 mW and obtain an ultra-narrow linewidth of 5.3 t 0.3 kHz. We investigate the influence of gain film thickness uniformity in distributed feedback laser performance and show a compensation scheme based on a curved cavity design. We then consider the application in optical communications by demonstrating a multiwavelength cascaded laser to generate wavelength division multiplexing (WDM) light sources. Finally, we propose an integration scheme of laser in full silicon photonics platform by using an erbium trench. The approach is alignment free and allows the erbium-doped film deposition to be the last backend process, providing a pathway to a scalable CMOS compatible laser device.by Purnawirman.Ph. D

Femtosecond laser pumped by coherent polarization locked diode.

We developed coherent polarization locking technique that significantly improves the brightness of the diode bar, which in turn is used to pump solid state bulk laser to obtain low-cost femtosecond laser source. The coherent locking consists of external cavity that combines emissions from arrays of emitters in the diode bar while their phases are passively locked via polarization discrimination. By designing a cavity with spatial filter, we demonstrated single mode coherently locked laser diode with maximum power of 1 W. We further scaled the power to more than 7.2 W by designing a cavity that combines multimode emissions from the emitters while compensating the smile effect by retro-reflector configuration. Both laser systems demonstrated brightness improvement over an order of magnitude compared to the conventional diode bar. We obtained 2.35 ps pulse width of 18 mW average power from Er, Yb: Glass laser by using single mode coherently locked diode. From the multimode coherently locked diode, we obtained 177 fs pulse width and 0.55 W average power of Yb: KYW laser.​Master of Scienc

Design of a passively Kerr-lens mode locked Cr : LiCAF laser.

To design the femtosecond laser for Cr: LiCAF, cavity simulation and the pump source were discussed. Continuous wave and Kerr lens mode locking was simulated by using MatLab. The simulation show comparable results to the existing experiment. The pump source was 690 nm diode laser. The diode laser was coherently locked using innovative design of birefringence crystals. The birefringence crystals property was characterized by using polarization method. The characterization is believed to be able to achieve more than 97% accuracy. In the last part, polarimeter and polarization controller was built to facilitate the polarization characterization. The performance of the polarimeter and polarization controller can transmit more than 94% efficiency.Bachelor of Science in Physic

Coherent polarization locking of multimode beams in a diode bar

We demonstrate coherent polarization locking of multimode beams from four broad area emitters in a diode bar. The beams are overlapped into single output by using walk-off crystals and waveplates while their phases are locked via polarization discrimination. Coherent locking of multimode beams enabled power scaling of coherent diode output while retaining beam quality of single emitter. We obtained power of 7.2 W with M2 of 1.5 x 11.5 from a 980 nm diode laser. This corresponds to brightness improvement of more than an order of magnitude.Accepted versio