5-wavelength surface emitting laser diode array based on post growth adjustment of surface mode emission

A five-wavelength surface emitting laser diode array based on surface mode emission is reported. The wavelength control is achieved by postgrowth adjustment of the surface structure. Wavelength spacing between laser groups is 1.1 nm in average and the wavelength reproducibility is ±0.13 nm. The total change in the emission wavelength over the array is 4.78 nm. The single array elements show single mode emission with a full width at half-maximum of 0.08 nm in average and a side mode suppression ratio up to 20 dB. This type of laser diode is of high interest for wavelength division multiplexing applications.

Fiber Bragg grating (FBG) sensors were used to measure the torsional strain distribution in a second-generation (rare-earth) Ba2Cu3Oy high-temperature superconducting sample tape (SST) at 77 K. Two SST samples were prepared. A slit was fabricated in each sample to allow an optical fiber to be embedded. In the first sample, a 10-mm-long single grating element was inserted into the slit. In the second sample, three grating elements of 10-mm length each were put into the slit. These grating elements were fabricated along a single-mode fiber and could be addressed individually using the wavelength division multiplexing (WDM) technique. Finally, the samples were recoated with a primary and secondary coating to form an embedded sensing system. When the high-temperature superconducting (HTS) tape is subjected to torsion, there is a strain induced in the FBG sensor, which varies the grating period accordingly. It was interrogated using a tunable laser in a WDM scheme. Based on the wavelength shift and the photoelastic properties of the FBG sensor embedded to the HTS tape, the torsional deformation of the HTS tape can be obtained. In this paper, the design and technology requirements to embed the single and WDM FBG sensors into the coated conductors are presented. Initial experiments to measure the torsional strain distribution at 77 K are reported.

The paper describes a new high NA planar microlens witha swelled structure (S- PML) designed for a laser diode (LD) array. The center to center spacing of the S-PML is 250 micrometers which is adjusted to the most ordinary LD array to be used in optical fiber communication system. The diameter of the S-PM is 85 micrometers and the focal length is 110 micrometers . The NA of the S-PML is 0.37. We evaluate the coupling loss between an LD and a single mode fiber using the S- PML. The coupling losses were 6.2 dB for 1.3 micrometers LD and 7.6 dB for 1.55 micrometers LD, respectively.

We report on the high-power high-temperature long-pulse performance of the 8XX-nm diode laser bars and arrays, which were recently developed at Lasertel Inc. for diode laser pumping within high-temperature (130 °C) environment without any cooling. Since certain energy in each pulse is required, the diode laser bars have to provide both high peak power and a nice pulse shape at 130 °C. Optimizing the epi-structure of the diode laser, the laser cavity and the distribution of waste heat, we demonstrate over 40-millisecond long-pulse operation of the 8XX-nm CS bars at 130 °C and 100 A. Pumping the bar with 5-Hz frequency 15-millisecond rectangular current pulses, we generate over 60 W peak power at 100 A and 130 °C. During the pulse duration, the pulse shape of the CS bars is well-maintained and the power almost linearly decays with a rate of 1.9% peak power per millisecond at 130 °C and 100 A. Regardless of the pulse shape, this laser bar can lase at very high temperature and output pulse can last for 8 ms/2ms at 170 °C/180 °C (both driven by 60 A current pulses with 5-Hz frequency, 10 millisecond pulse width), respectively. To the best of our knowledge, this is the highest operating temperature for a long-pulse 8XX-nm laser bar. Under the condition of 130 °C and 100 A, the laser bars do not show any degradation after 310,000 10-millisecond current pulse shots. The performance of stack arrays at 130 °C and 100 A are also presented. The development of reliable high-temperature diode laser bar paves the way for diode laser long-pulse pumping within a high-temperature environment without any cooling.

Wavelength division multiplexing (WDM) is a data transmitting technology, which allows the sending of a several optical signals from different sources over the same optical fiber. Today, WDM technologies allow maximizing the use of both the existing and the new fiber optic infrastructures. According to the International Telecommunication Union (ITU) for the WDM standards, optical multiplexers and demultiplexers must handle closely wavelengths for the optical data channels. The use of WDM has reduced the fabrication cost and eased the process of realization. Optical fiber components have very low insertion losses to insert or to extract a specific optical data channel from a WDM network. Various optical fiber components designs and implementations are possible. In this paper we expose the use of electrical arc and micro deformations for writing the long period fiber gratings (LPFG) on a single mode fiber. We take a closer look at the design of this component which has several advantages compared to similar components. In fact, the realized LPFG has stronger wavelength stability when opposed to temperature variations and a better resistance against mechanical strength. These advantages makes the LPFG so important in the industry.

Distributed fiber optic vibration sensing with wide dynamic range, high frequency response, and multi-points accurate location

The paper proposes a scalable wavelength-switched optical NoC, named as SWS-ONoC. The proposed architecture is built upon a novel all-optical router which passively routes optical data streams based on their wavelengths. Utilizing wavelength routing method, SWS-ONoC eliminates electrical transactions for optical resource reservation and hence, reduces latency and area overheads of the electrical units. The proposed architecture benefits from Wavelength Division Multiplexing (WDM) scheme to efficiently route multicast optical packets concurrent with unicast data streams. Performing a series of simulation-based experiments, we study efficiency of the proposed architecture, its power and energy consumption, and data transmission delay under a hybrid traffic pattern, composed of multicast and unicast packets.

We demonstrate an on-chip 0.96 TOPS hyperdimensional photonic tensor core by utilizing a time-space-wavelength multiplexed silicon photonic Crossbar (Xbar). The novel architecture relies on serializing the large matrix-vector or tensor-vector products by unfolding multiply and accumulation operations over the time domain, while simultaneously distributing the computational workload over different spatial and wavelength channels. We experimentally demonstrate the operation of a 4-channel 2-input time-space-wavelength division multiplexing (TSWDM) Xbar that incorporates 56 GHz electro-absorption modulators (EAMs) and 4-channel integrated multiplexing stages. Its successful operation as a 4×2×1 tensor-vector multiplication unit demonstrated an average relative error of 3.9%. Its performance as a photonic AI accelerator was also evaluated in the classification task of the Iris dataset, presenting experimental accuracies of 93.3% at data rates between 4×10 and 4×30 GBd, reaching 83.3% when the data rate increases to 4×60 GBd. Finally, we discuss the TSWDM Xbar scalability potential, revealing that the inclusion of a wavelength division multiplexing (WDM) scheme in the space division multiplexing (SDM) architecture reduces the operating laser power, feasibly boosting the potential of constructing photonic accelerators with computational throughput in the POPS regime.

In modern times, where the speed of transmission is of utmost importance, often need arises for a reliable transmission medium. With innovations in LAN (local area networks) such as FDDI (fiber distributed data interface), fiber optic data links and associated interface schemes are gaining more and more acceptance and actually are becoming real necessities. In this article, the author describes a simple design methodology for a fiber optic data link and presents criteria to evaluate the performance and frequency response properties of these data links. In addition, a simple wavelength division multiplexing (WDM) scheme for improved data rate is also presented.

A multi-striped InGaN-based laser diode (LD) array is demonstrated at a high power of 6.3W under continuous wave operation. The world highest power operation as InGaN LD array is attributed to thermally optimized layout design taking an advantage of highly efficient emitters.

We report and analyze the supermode switching with current injection found for coherently-coupled dual-element vertical cavity surface emitting laser arrays. The output power, spectral characteristics, and far-field mode profile are measured for a range of bias current operating conditions. The coupling-induced enhanced output power from an in-phase or out-of-phase supermode is confirmed when approximately equal currents are injected into each array element. We observe that the coherent supermode switches from out-of-phase to in-phase supermode with increasing equal current injection. The switching is found to be consistent with coupled mode theory and a 1-dimensional spatial supermode model. The calculated modal gain of the out-of-phase and in-phase array supermodes are consistent with the observed switching of the coherent supermodes.

This paper presents a new low-cost, multi-layer interconnection architecture, which has the potential of being utilized in a space environment. Instead of conventional electrical input/output (I/O) pins, optical I/O pins are used to provide multi-layer interconnection. A small vertical cavity surface emitting laser diode array and photodetector array are used to transmit and receive signals, respectively. A specially fabricated end-face lensed fiber array is utilized to provide high-speed, low-loss, and low-crosstalk signal transmission. By employing this new optical I/O pin architecture, many types of standard multi-layer interconnection can be easily realized. This presentation covers the main concepts, major components, fabrication procedures, and expected applications of this architecture.

We show in simulation and experiment that the coherent coupling of electric fields between elements of a triangular photonic crystal vertical cavity surface emitting laser array can be adjusted into antiguided supermodes with approximately equal injection into each array element. The dominant supermodes are found by a complex waveguide mode simulation and can be identified by the number and arrangement of side-lobes of their Fourier-transformed far-field beam profiles. The supermode with all three elements in-phase is found to possess the minimum central lobe angular divergence. Measurements of the continuous wave coherently coupled properties of photonic crystal triangular arrays, nominally emitting at 850 nm, are compared to our simulations. We show that the array can be adjusted to lase in a desired supermode by varying the injection currents into each element of the array. The optical power confined within the central portion of the in-phase coupled beam is greater than that emitted from a single VCSEL which is advantageous for high-brightness applications.

Summary form only given. Wavelength division multiplexing (WDM) technology is very important for optical fiber communication systems to increase transport capacity. However, one of the problems encountered when using InGaAsP/InP laser diodes (LDs) is that the lasing wavelength fluctuates with ambient temperature variation mainly due to the temperature dependence of the bandgap energy. To overcome this problem, we proposed TlInGaAs(P) as new III-V semiconductors showing temperature-independent bandgap energy for the possible application to the temperature-stable lasing wavelength LDs. We have already succeeded in the growth of TlInGaAs/InP double-hetero (DH) structures and obtained the very small temperature variation of the photoluminescence (PL) and electroluminescence (EL) peak energies. In this paper, we will report the gas source MBE growth of TlInGaAs/InP LD wafers and their first successful laser operation.

An optical fiber sensor network for ultrasonic measurement based on wavelength division multiplexing (WDM) and time division multiplexing (TDM) technology is presented. Each of the sensor probes is an optical fiber extrinsic Fabry-Perot interferometer (EFPI) which is composed of the fiber's end face and the aluminum thin diaphragm. The sensors are arranged in different wavelength domains formed by a wavelength division multiplexer. Each wavelength division multiplexer, with a group of the sensors, is connected to one of the output ports of optical switch to realize TDM. The signal of each sensor is exported sequentially from a tunable narrowband optical filter (TNOF) that queries every sensor though scanning mode. The principle of the phenomenon of phase induced signal fade in interferometric fiber-optic sensors is also analyzed. Nicely, the detection method above implements the operation of anti-phase induced signal fade detection. The system is interrogated by broadband light source. The scanning range of TNOF is full of the bandwidth of the light source. The result of experiment in water show that the sensor sensitivity reaches −162dB(0dB=1rad/μPa), the frequency response range is from 10KHz to 5 MHz. The number of multiplexing sensors based on WDM and TDM reaches to 64.