Optiwave Systems (Canada)

Special cavities like Figure-8 and Figure-9 are exploited in lasers to enable self-starting passive mode-locking using nonlinear amplifying loop mirrors (NALMs) or nonlinear optical loop mirrors (NOLMs). Their significance lies in enhanced nonlinearity and intracavity feedback, enabling stable, self-sustained mode-locked pulses suitable for ultrafast fiber lasers. In this paper, we propose the design of femtosecond pulse width passively mode-locked Holmium-doped fiber laser (HDFL) operating at 2090 nm and 12.5 MHz repetition rate based on Figure-9 (F9) cavity. The F9 cavity is implemented utilizing three different reflectors, including saturable absorber (SA), simple mirror (SM), and fiber loop mirror (FLM). The performance of the proposed laser is compared for different reflectors considering characteristics of slope efficiency (SE), pulse width, optical signal to noise ratio (OSNR), peak power, and pulse energy. SA, SM, and FLM configurations yield mode-locked pulses with SEs of 35.6%, 8%, and 8.8%, pulse widths of 357.2 fs, 294 fs, and 231 fs, OSNRs of 36.4 dB, 46 dB, and 50 dB, peak powers of 13.53 kW, 6.12 kW, and 9 kW, and pulse energies of 4.83 nJ, 2 nJ, and 2.1 nJ, respectively. The analysis reveals that the FLM-based reflector achieves the shortest pulse width and highest OSNR, while the SA-based reflector delivers the highest peak power and pulse energy, highlighting trade-offs between pulse quality and energy performance in the proposed laser design.

We investigate analog and digital pre-emphasis for ultra-high-bit-rate coherent dual-polarization 64-QAM (DP-64QAM) transmission using OptiSystem. Two representative single-wavelength configurations are studied: 64 Gbaud (600 Gb/s payload, 768 Gb/s line rate) and 100 Gbaud (1000 Gb/s payload, 1.2 Tb/s line rate). The transmitter employs raised-cosine pulse shaping (roll-off 0.1) and a 9-bit DAC, while the receiver uses a 9-bit ADC; bandwidth-limiting Bessel/Gaussian filters emulate practical transmitter (Tx) and receiver (Rx) front-end constraints. Analog pre-emphasis (APE) is realized by uploading a measured analog filter response immediately after the DAC to compensate high-frequency roll-off. Digital pre-emphasis (DPE) is implemented before the DAC as a finite-impulse-response (FIR) pre-distortion stage, with taps obtained from the measured frequency response via spectrum mirroring, inverse FFT, Hamming-window smoothing, and normalization. We compare four cases: (i) ideal reference without bandwidth limits; (ii) bandwidth-limited without pre-emphasis; (iii) APE; and (iv) DPE. Bit-error-rate–versus–optical signal-to-noise ratio (OSNR) results show that both APE and DPE substantially mitigate bandwidth-induced penalties and approach the theoretical bound, reducing the OSNR gap to 5.8 dB at 64 Gbaud and 6.6 dB at 100 Gbaud, with operation near the forward error correction (FEC) threshold (BER=10−2). While DPE offers full programmability, it increases peak-to-average power ratio (PAPR) and may require additional gain headroom. Overall, APE provides an effective rapid-prototyping step prior to DPE deployment, confirming the feasibility of 768 Gb/s and 1.2 Tb/s DP-64QAM links with commercially realistic components, including a 150 GSa/s DAC operating at 1.5 samples/symbol for 100 Gbaud.

The wavelength division demultiplexer (WDD) is an indispensable component for separating and routing photons to spatially distinct detection nodes in practical quantum key distribution (QKD) systems. In this work, we propose an ultra-low-loss and broadband WDD based on lithium niobate on insulator (LNOI), designed and optimized through comprehensive three-dimensional simulations, utilizing subwavelength grating (SWG)-assisted double directional coupling for the separation of 780 and 1550 nm wavelengths. The SWG waveguide enables both a compact footprint and low insertion loss (IL) over a broad wavelength range, making it well suited for QKD applications. The optimized device, with a total length of 45 µm, achieves ILs of 0.04 dB at 780 nm and 0.22 dB at 1550 nm, along with extinction ratios of 22 and 32 dB, respectively. The 0.5 dB bandwidth exceeds 140 nm for 1550 nm and 230 nm for 780 nm. Furthermore, the structure exhibits strong tolerance to fabrication-induced variations, supporting its suitability for robust and scalable photonic integration.

Photonic integrated circuits (PICs) are the key technology for reducing the footprint, energy consumption and lower costs of optoelectronic modules. Characterizing these PICs is necessary not only at the chip level but also at the system level. OptiSystem software plays a key role enabling designers to evaluate their PIC designs. Integrating IPKISS software with OptiSystem supports a full optical communication system characterization of PICs. An automated characterization of a cross-connect switch and a ring resonator demultiplexer PICs conducted in OptiSystem.

We demonstrate a compact two-dimensional optical phased array that routes light on-chip using evanescent coupling between a bus waveguide and antenna elements. With this method, the integration of hundreds of antennas in a compact design space is possible. An 8×20 OPA is fabricated and achieves a steering range of 31.4°.

ABSTRACTWater presence in raw meat not only degrades its quality by diluting the natural flavours, but also increases the risk of bacterial growth, altering texture, and juiciness which ultimately affects the quality of end products. Therefore, quality assessment of raw meat in markets as well as in eateries is important to ensure the consumer's safety and satisfaction. In this paper, we propose a nondestructive technique to detect water presence in raw meat and steak cooking temperature optimisation using a fibre Bragg grating (FBG) temperature sensor inserted into the piece of raw meat. The contribution of this paper is twofold: First, the water presence in the piece of raw meat is detected by analysing the shift in Bragg wavelength corresponding to time‐dependent gradual decrease in temperature of heated probe of FBG sensor due to convective heat transfer from probe to meat. Secondly, the optimum cooking temperature of a particular type of steak is achieved after quality assessment of meat by analysing the shift in Bragg wavelength corresponding to time‐dependent gradual increase in probe temperature due to convective heat transfer from meat to probe. The results show that the proposed sensing system can complete the error‐free detection of water in 250 g piece of raw meat within 30 s for water contents of 50, 75, and 100 g which account for 20%, 30%, and 40% of the net weight of meat, respectively. Moreover, the simulated and experimental values of temperature sensitivity (TS) of FBG sensor used in this work are around 13 and 10 pm/°C, respectively. The proof of the concept of a smart restaurant based upon the proposed work is also discussed. This study provides a nondestructive, simple, and fast solution for detection of water in raw meat and achieving the optimum cooking temperature for different types of steaks.

Abstract Flatness of lasing wavelengths of a multi-wavelength fiber laser (MWFL) is an important design constraint that is considered attractive in various applications of photonics and optical communication systems. In this work, we propose a single-longitudinal mode (SLM) quadruple wavelength C+L-band Erbium-doped fiber laser (EDFL) with high output power flatness. It is implemented with a short piece of Erbium-doped fiber (EDF) pumped by conventional 980 nm laser diode and four pairs of reflective fiber Bragg gratings (FBGs) through numerical simulations. The reflectivities of FBGs are adjusted such that SLM quadruple wavelengths are obtained at the output of EDFL with flatness of 0.9 dB, optical signal-to-noise ratio (OSNR) in the range of 44.5–53.2 dB, and linewidths (LWs) in the range of 5.4–7.3 MHz. Slope efficiency (SE) of around 24% is achieved considering the total power of all lasing wavelengths generated. Moreover, the power variation around 0.1 dB for lasing wavelengths of 1540.2 nm and 1605.7 nm is noticed for twelve iterations each repeating after five-minute interval. The proposed SLM quadruple wavelength EDFL has promising application prospects for distributed sensing and optical communication systems due to excellent performance metrics.

The Internet of Underwater Things (IoUTs) connects underwater devices to communicate, sense surroundings, and transmit data. Acoustic communication faces bandwidth limitations, making underwater wireless optical communication-free space optics (UWOC-FSO) hybrid systems a promising alternative. However, maintaining sufficient power budget and signal-to-noise ratio (SNR) is a challenging task, making wavelength translation (WT) from visible to infrared (IR) at the water-fiber-air interface crucial for reliable signal transmission. In this paper, we propose an underwater wireless optical communication-single mode fiber-free space optics (UWOC-SMF-FSO) hybrid link based on a photo-detection, remodulate, and forwarding (PRF) relay and intensity modulation-direct detection (IM/DD) scheme for 8 × 1-Gb/s underwater optical wireless sensor network (UWOSN). The PRF relay is installed at a remotely operated underwater vehicle (ROV) to perform WT from visible range to IR. The performance of the sensors is analyzed for different water bodies and weather conditions of underwater and free space optics channels, respectively using metrics of Bit-error rate (BER) and Quality factor (Q-factor) employing Gamma–Gamma channel model. The simulation results show that forward-error correction (FEC) target BER of 10−4 for sensors is achieved under different water bodies and weather conditions. The results obtained from this study show that the proposed UWOC-SMF-FSO hybrid link is flexible, resilient to adverse channel effects, and can be a potential candidate for implementation of high-speed long-distance future IoUTs.

The safety of SCUBA divers remains at high risk in deep-sea owing to multiple factors such as dangerous surrounding, rely upon technical equipment necessary for life support, decreased underwater navigation, and communication infrastructure. Gradual decrease and increase in water temperature and pressure corresponding to depth are among the most common problems that cause most of the fatalities in deep-sea diving. Therefore, different gadgets for accurate measurement of vital parameters, reliable navigation, and seamless communication are of prime importance. In this paper, we propose an all-optical technique for local and remote monitoring of underwater temperature and pressure for deep-sea SCUBA divers based on fiber Bragg grating (FBG) sensors and underwater optical communication-single mode fiber (UWOC-SMF) integrated transmission system. The proposed technique is implemented using two FBG temperature and pressure sensors fixed over diver’s suit and UWOC-SMF integrated transmission system for simultaneous local and remote monitoring of underwater temperature and pressure. Remote monitoring of underwater temperature and pressure is achieved at ship station through a remotely operated underwater vehicle (ROV) and UWOC-SMF integrated transmission system by means of shifts in the original Bragg wavelengths of sensors due to temperature and pressure variations. The performance of the sensors is analyzed for pressure and temperature in the range of 0 to 6.4 MPa (≈0 to 655 mH2O) and 40 to −2°C, respectively corresponding to different depths. The results show that the proposed technique can work well in the deep ocean over a range of pressures and temperatures of 0–7 MPa and 40 to −2°C while achieving a temperature sensitivity of 4.3 p.m./°C and a pressure sensitivity of 30.5 p.m./MPa. Clear spectra of reflected signals from FBG sensors at ship station are achieved after signal transmission over UWOC-SMF hybrid link.