We have demonstrated a single-mode lasing with a narrow single-lobe beam emission from InP-based double-lattice photonic-crystal surface-emitting lasers (PCSELs) in a wide temperature range from 25°C to 80°C under CW condition. A high output power of 240 mW is achieved at a temperature of 25°C. The lasing occurs even at a high temperature of 80°C, and the output power is 48 mW. The single-mode lasing and the narrow single-lobe beam with divergence angle below 1.5°, which is a unique feature of PCSELs, are maintained even at a high temperature of 80°C.
We report on development and characterization of 850 nm vertical-cavity surface-emitting lasers (VCSELs) having a -3dB modulation bandwidth above 24 GHz with a flat frequency response at temperatures up to 85°C. Aperture size is optimized for a high relaxation oscillation frequency with a narrow spectral width and low relative intensity noise. Two types of VCSELs (Gen 1 and Gen 2) with different epitaxial designs are fabricated with an optimized aperture size. Large-signal modulation at 53 GBd PAM-4 (106 Gb/s) is performed for eye diagram and TDECQ measurements. The Gen 1 VCSEL is capable of 53 GBd PAM-4 modulations at temperatures up to 70°C, but performance is insufficient at 85°C. The Gen 2 VCSEL with a stronger optical confinement achieves higher modulation bandwidth with an extremely suppressed resonance peak in frequency response, leading to reduction in TDECQ compared to the Gen 1 VCSEL. TDECQ below 4.5 dB are verified at temperatures up to 85°C without any pre-emphasis in the transmitter. Also, we use a pre-emphasis with 3-tap feed forward equalizer to improve the TDECQ by 2 dB. Furthermore, after the transmission over 100 m multimode fiber (OM5), the TDECQ keeps below 3.0 dB even at 85°C. These results demonstrate the capability of 850 nm VCSELs for 100 Gb/s per optical lane short-reach interconnects operating over a wide temperature range
In the recent decade, the growth of data centers is being driven by spreading of cloud computing and its relevant technologies. As of now, 100 Gbit/s optical interconnects have been widely used in the data-centers, and the trend is about to be switched to 400 Gbit/s data-rate. Multi-mode VCSELs are employed for the reasons of the lower cost and power consumption in a short-distance range. 400 Gbit/s transceivers are equipped with an 1×8 or a pair of 1×4 VCSEL arrays. Especially, 400GBASE-SR4.2 (BiDi) uses two different wavelengths for each 1×4 array. In such case, sufficient uniformity in terms of optical output, bandwidth, relative intensity noise (RIN) and spectral width properties could be keys to success in 400 Gbit/s applications. Variations of optical output and bandwidth over a processed wafer can be suppressed by maturing the epitaxial growth and fabrication procedures. In contrast, spectral and noise properties are strongly coupled to transverse mode properties of VCSELs, which are controlled by a shape of the oxide aperture. In this work, we report uniform spectral and noise characteristics of 1×4 VCSEL arrays by introducing a rotationally-asymmetric oxide aperture. The rotationally-asymmetric aperture VCSELs show less variation in root-mean-square (RMS) spectral width and RIN compared with circular-aperture VCSELs. The rotationally-asymmetric aperture is capable of splitting degenerated modes in spectral domain. Uniformity in the performance of optical output, 3dB bandwidth and RIN are verified in 1×4 arrays for both 850 nm and 910 nm VCSELs. 53.125 Gbit/s PAM-4 modulation is then performed with different temperatures of 25 and 90℃, which shows the capability of our VCSEL arrays for 400 Gbit/s applications.
The authors have succeeded in employing nanoimprint lithography (NIL) to form diffraction gratings of distributed
feedback laser diodes (DFB LDs) used in optical communication. We have fabricated more than 300 phase-shifted DFB
LDs on a 2-in. InP substrate. The devices have indicated comparable characteristics including uniformity and reliability
with those fabricated by conventional electron beam lithography. We have also demonstrated a novel concept of a mold
containing various types of grating patterns in a field ("VARI-mold"). By utilizing the new mold, DFB LDs with various
emission wavelengths are formed simultaneously on a wafer. It indicates that one VARI-mold is possible to be applied to
various kinds of product, leading to the cost reduction of the molds and the total NIL process. The results of this study
indicate that NIL is a promising candidate of the production technique for phase-shifted DFB LDs featuring low cost and
high throughput.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.